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Community => Rohloff Internal Hub Gears => Topic started by: Danneaux on July 20, 2012, 06:30:05 PM

Title: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on July 20, 2012, 06:30:05 PM
Hi All!

As someone new to Rohloff who is in the setup and choosing phases, I find myself wondering what chainring/cog combinations others have chosen and favor for their Rohloff-equipped bikes.  It'd be nice as a poll, but too confusing to set up and vote on...just too many combinations to be wieldy.

So, I'm hoping some of you might be kind enough to post your combo and perhaps a comment or two on...
1) How is the low working for you in your conditions/use.
2) Is the direct-drive Number 11 gear working out to be your most-used, or have you compormised on that to get the low/high you'd like?
3) How important has placement of the 7/8 split been to you?

With regards to this last, it seems best to consider "high range" (8-14) as the most-used cruising range, and the "low range" (1-7) as just that -- for slogging along at lower speeds, climbing hils, plowing through mud, going into headwinds, and so forth, with Gear 11 as the most-used direct-drive. 

If so, and with all considerations, it seems the best gearing for me might be the lowest combination permitted by Rohloff while maintaining full warranty coverage against possible breakage -- 40x17. My most-used level-cruisiing gears on my other bikes are either 58 gear-inches (early-season or if I've been off the bike a little while) or 62 gear-inches (pretty much anytime I'm riding flats) with a steady cadence of averaging around 110RPM to make up for the low gearing with fast, light revs. The 40x17 would put my Gear 11 right at 61.2 gear-inches, which is spot-on.

In reading the earlier version of Andy's "Living With a Rohloff" that appears on Sheldon's site ( http://sheldonbrown.com/harris/rohloff-impressions.html ), I see he mentioned a carefully chosen and well-reasoned 36x17 with all factors considered, resulting in a 15.4 low. While that low would be most welcome for what I so often do (ride with heavy touring loads up really steep hills and across sometimes very soft desert playa), I'm concerned about the possibility of breakage and warranty issues. It would also put me in 12th gear a lot, as 11th with that setup is a bit low for me. Given that, a 40x17 again seems like a pretty good match for my needs. My knees will never pull more than the 89.9 high it offers.

As for my overall range...
I have occasionally geared my bikes to offer low gearing in the mid-teens (15-16 gear-inches) and was delighted with the result, but do not want gears that low at the expense of reliability. At the high end -- particularly with a full touring load -- it is unlikely I'll ever use anything much above 85 gear-inches, given my high-cadence/low gear pedaling style.

Looking forward to all responses and any helpful suggestions you might be able to offer; thanks in advance! While I am familiar with derailleur bicycles, I am all-new to the Rohloff drivetrain, and learning as much as I can before my bike reaches final spec.

Best,

Dan.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: wheezy on July 20, 2012, 06:51:42 PM
38t x 16t, on a 700c/29er. Roughly 19-100 gear inches.

Plenty of range for an MTB and an almost brisk, flat-bar road bike. I'm rarely aware of the actual gear I'm in, unless it's top or bottom. I can tell whether it's 1-7 or 8-14 by the faint whirring and the feel through the pedals in the lower range, but that's about it. I'd say forget about the 7-8-7 shift. I personally don't notice it.

Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: triaesthete on July 20, 2012, 08:16:12 PM
Hi Dan
I would suggest as low as you can go but maybe on 38x16 for the even even sprocket combo Sheldon recommended to reduce wear. If you don't need 90"+ and want to stay within the law this is your only alternative.
My hub is quietening down very quickly due to extensive rough track hillclimbing. First is now very quiet as it has had a pounding. Two to seven whirr a bit but not annoyingly and are getting quieter. Like wheezy I don't notice the 7-8 change being any different to the others.
Most of the time now I don't know or care what gear I'm in I just use what I need when I need it,  and thats a simple choice higher or lower. No more juggling two shifters or toughing it out on the middle ring.
This sort of stuff will grow on you with familiarity
enjoy
Ian
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: JimK on July 20, 2012, 08:35:55 PM
I have 38x16 (with 26 inch wheels).

 I don't notice 11 as anything special, but I definitely notice the 7-8 transition. 8 feels a lot more efficient than 7 - of course I am aware that this is probably an illusion caused by the noise in 7. Also the 7-8 or 8-7 transitions are a bit rougher/slower, but that is a very small issue. Shifting my hub is delightfully easy even then.

I use the full range of gears regularly. As I ride more I am getting stronger so I do notice I am not in 1 as much anymore, but getting up any real hill means a lot of time in 1. And we have lots of real hills in the Catskills!

On the Erie Canal ride we had a lot of flat terrain. I noticed that I was mostly in gear 9 riding about 11.5 mph or maybe gear 10 riding more like 12.5 mph. That kind of steady riding is not the norm around here where I live, where is it up and down, constantly shifting!

 
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on July 20, 2012, 10:29:34 PM
As Ian says, we familiars are superior for a reason...  :)

I too use 38x16 on 29er tyres, 60x622, because I live up a steep hill. (I didn't always have motor assistance.) It is the lowest legal ratio (2.375) and it gives me 19.5 gear inches, 5.6kph at 60rpm, to 102.6 gear inches, 29.5kph at 60rpm. In theory that's a bit short at the top end but I don't mind cruising downhill. Gear 11, 1:1, gives 69.9 gear inches, 20.1kph at 60rpm. EDIT: Unlike Jim, I liked gear 11, and most of my riding was built about it, but now, just like Jim, and despite two doses of heart surgery, I ride a bit stronger, perhaps from pure joy at being alive and out on my bike, and have been noticing that I'm all the way up into gear 14 (overdrive) even on the milder inclines quite often.

Back when I got the Rohloff, I would have gone to 36x16 if I needed it, and happily sacrificed the warranty for it. It turned out that my German dealer was not such a scofflaw; he wouldn't fit unauthorized parts or even supply them loose! But, though I've since bought the parts for some other ratios, when the opportunity arose to make a change, either way, I stuck to 38x16 because it just flat works for me.

Andre Jute
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: martinf on July 21, 2012, 07:28:55 AM
I've done a lot of riding with SA 5-speeds, and reckon larger sprockets last longer and prolong chain life.

Not yet got a Rohloff, but I was thinking of getting the more expensive optional 21T sprocket, coupled with a 50T chainring.

50x21 ratios are about the same as 40x17, range about 17" to 90".

This is about the same as the 18" to 87" derailleur setup I had for my last loaded tour, my lowest gear was dictated by the smallest available chainring and largest available sprocket for my equipment.

I wouldn't use a 90" top gear much, and 11th gear at about 61" is slightly higher than my most-used gear on flat terrain, but with a new Rohloff I wouldn't want to gear lower than the permitted combinations for the first few thousand kms in case the hub is one of the few that have to go back to the factory for modifications.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Neil Jones on July 21, 2012, 08:39:34 AM
Hi Danneaux,
I was in exactly the same position as you and spent far too much time researching chainring/cog combinations, in the end I phoned the friendly people at SJS Cycles and Robin recommended a 40x17 which to be honest I was a bit sceptical about at the time, anyway to cut a long story short they got it spot on. I live in North Wales which is very hilly and find myself constantly changing gear but on the flat I'm usually in gears 11 or 12. I sometimes wish I had a couple of higher gears (I spin out on hills once I reach about 26 mph) but as I don't wear a helmet it's probably for the best and I've never used the bottom 3 gears (I haven't cycled fully loaded} so perhaps there is room to fine tune when it's time to replace the ring and cog.
By the way I bought my RST 18 months ago and it's the best bike I've ever owned. I use it to commute to work mainly and have covered about 4000 miles in all weathers. The only thing I've ever done is changed the oil and the chain and it is so much easier to clean too.
I will never sell my RST as it suits my purpose perfectly although I do hanker after a Thorn Audax as I would like a lighter more responsive bike to ride on my days off.
Good luck Danneaux, you won't be disappointed I'm sure.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on July 21, 2012, 09:00:45 AM
Hi Martin!

Very nice having you aboard; welcome!

Quote
... reckon larger sprockets last longer and prolong chain life. Not yet got a Rohloff, but I was thinking of getting the more expensive optional 21T sprocket, coupled with a 50T chainring.
I spent some time this evening with the Rohloff gear chart and it -- along with the SJS Cycles site's Rohloff cog offerings -- had me thinking along similar lines.

Thinking about Ian's reference to Sheldon Brown's even-even gearing combos, I wondered if the even-odd (40-17) setup might result in a wash, where wear is concerned. Yes, it is a mismatched combo in terms of tooth count, but the larger diameter compared to the 38-16 might come out the same in terms of service life even with greater wear due to the odd sizing. Certainly, the 38-16 is more economical -- that 21 tooth cog costs nearly twice as much. The 16T is £25.99, while the 17T is a modest increment upward at £29.99, and the 21T is £49.99 (USD$ $40.37, $46.59, and $77.66 respectively at current exchange rates).

The 21T cog and 50T chainring would have to effectively double drivetrain life to cost-out effectively. If chain life is factored in...maybe it would. Also, thinking about the sizing of the timing rings on my tandem, I think torque loads on the bottom bracket would be reduced as well. I went to far larger timing rings and now my bottom brackets last forever. Something for me to ponder further. One point Andy makes in his "Living With A Rohloff" articles is how the larger 17T cog contributes to longer chainlife because -- while there is no lateral stress on the chain compared to a derailleur application -- the chain doesn't have to wrap as tightly, saving wear. To get equivalent overall range with the 17T cog as the 16T also means increasing the chainring size, so the chain is stressed less at both ends (larger arcs) -- a less extreme version of what Martin is considering, but also at less initial outlay.

I'd love a low gear around 15 gear-inches, but like Martin, I'm concerned about compromising my standing with the Rohloff warranty. And, in the back of my mind, I'm a bit concerned about the potential for actual breakage out in the field, however unlikely that might be. It isn't a complete stopper, and it doesn't seem to be a problem in practice, but it really is possible to generate pretty high torque loads when starting from a stop on a 24% grade with 32kg/72lb of gear.

In earlier days ( <cough> late 1970s <cough>), I developed maps of routes that pioneered the Eugene Hill Tour. It was later taken up by local clubs and became an annual event and even a fundraiser for them. I was deep into gearing then and caught the low-gear bug (logarithmic graph paper days. Australians, do you remember Ron Shepard and his ultra-low gearing efforts/Low Gear Fellowship from that era? He used FW cogs up front and chainrings behind). I modified a number of older cranksets to take freewheel cogs (pre-Mountain Tamer Quad days, too, though I got one of those in due course). I found it is possible to actually ride a 12-inch low gear with a load, provided the hill is steep enough. Biggest problem was catching the pedal cage with my shoe cleat -- the crankarm whipped around so fast at that point, it usually took till the third go-'round to catch it, so I started out in second or third gear, then shifted down once underway.

The thing is, as my gearing got ever lower, torque on the rear hub and freewheel components grew greater and greater. I never broke anything, but I soon had a terrible time getting the freewheels off the hub -- they would screw on so tight, they distorted the land next to the freewheel threads. I finally solved the removal problem by coating both hub and freewheel threads with molybdenum disulphide high-pressure lube and then using crushable (sacrificial) aluminum spacers between the freewheel body and the hub. As you can probably imagine, my chain life dropped dramatically, and this was in the days when a 5-sp Regina Oro was a really robust chain. heavy, anyway.

The lesson I took from these efforts is my output remained essentially the same within anobjectively narrow range. What changed was the effective torque multiplication due to the lower gearing, and I think this is what Rohloff is concerned about. I strongly suspect even the "red" or "illegal" Rohoff gearing combos don't kill the hub outright or even for a very long time or at all, unless the rider is really strong or other factors are in play (hill slope, heavy load, etc). I'm guessing these deep ratios do eat into the service life/MTBF (mean-time between failure) ratings Rohloff have specified so there is less "cushion" or safety margin before something goes Bad. This effect is bound to be more risky when it is still early days for a hub, and the gears and internals have not worn into full mesh and contact with one another. After the hub is broken in, it seems considerably less risky.

I am still boggled by the realization that all that forward torque is countered by such a small reaction-moment arm -- the thing fits inside the dropout! Pretty astonishing when you think about it, and it makes me happy Thorn have spent so much effort to craft their left-hand dropouts with great care. Kinda makes me wonder about the aluminum OEM Rohloff dropouts, but there's a lot of "beef" in them as well, and they're really thick.

Oh! While writing this, I see Neil has posted on this very topic -- talk about timely! Good having you weigh in also. Neil, I'm glad to hear the 40x17 has worked so well for you in practice, and to hear it does so on the kind of hills you reference is reassuring too. Thanks so much for your "user report" and now...boy! Now, I need to ponder all the input and come up with a spec. This is all outstandingly helpful, and I do so appreciate all your efforts and responses and kind wishes. Keep 'em coming, please! All sounds very promising to get an ideal ratio for my needs.

All the best,

Dan.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on July 21, 2012, 09:07:46 AM
Thinking about it more, Wheezy's post is going to have me running a quick comparison of "forbidden" gears between 700C and 26" wheels in the Rohloff charts. The larger 700C/29er diameter is bound to result in added stress that can be calculated (thinking about Shimano's cautions related to using their 12-36 cassette on hubs made specifically for it if 29er wheels are used). If the forbidden ratios are the same, I can get an idea of the safety margin Rohloff allow. If they are different, then Rohloff are making an adjustment for diameter-related torque increases on the hub internals.

Late enough now, so off to bed. A fine project for when I awaken.

Best,

Dan.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: il padrone on July 21, 2012, 09:13:15 AM
42-17 gives me a nice ~65" gear for gear 11 which is very nice as a comfy flat road gear. The 17 sprocket also reduces chain wear apparently - larger sprockets and chain-rings always wear slower as well.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: il padrone on July 21, 2012, 09:44:12 AM
With regards to this last, it seems best to consider "high range" (8-14) as the most-used cruising range, and the "low range" (1-7) as just that -- for slogging along at lower speeds, climbing hils, plowing through mud, going into headwinds, and so forth, with Gear 11 as the most-used direct-drive.  

This recommendation is the best guide you could use. I had a 42-16 to begin with and gear 11 was too high for me to use on flat roads mostly. I found myself using gear 10 mostly. The current high gear (with 42-17) is 94" and I will spin out at about 55kmh on steeper descents. This is rarely a real concern as by that speed, especially when fully-loaded, I will get more speed from going into a tuck than by pedalling.



In reading the earlier version of Andy's "Living With a Rohloff" that appears on Sheldon's site ( http://sheldonbrown.com/harris/rohloff-impressions.html ), I see he mentioned a carefully chosen and well-reasoned 36x17 with all factors considered, resulting in a 15.4 low. While that low would be most welcome for what I so often do (ride with heavy touring loads up really steep hills and across sometimes very soft desert playa), I'm concerned about the possibility of breakage and warranty issues.

My bike has a low gear of 17.9" and that is fine for  all sorts of loaded touring up to about 20% grades. I am quite amazed by the gearing Andy Blance runs as it looks to be about a 21 sprocket with a 38 or lower chain-ring. This is well below the specific recommendation from Rohloff.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on July 21, 2012, 10:02:15 AM
... with a new Rohloff I wouldn't want to gear lower than the permitted combinations for the first few thousand kms in case the hub is one of the few that have to go back to the factory for modifications.

Probably a smart consideration. Also, the hub will be run in, a little less likely to break from a sudden stress. I see Dan has also addressed the point.

Thinking about it more, Wheezy's post is going to have me running a quick comparison of "forbidden" gears between 700C and 26" wheels in the Rohloff charts. The larger 700C/29er diameter is bound to result in added stress that can be calculated (thinking about Shimano's cautions related to using their 12-36 cassette on hubs made specifically for it if 29er wheels are used). If the forbidden ratios are the same, I can get an idea of the safety margin Rohloff allow. If they are different, then Rohloff are making an adjustment for diameter-related torque increases on the hub internals.

The lowest ratio Rohloff permits has nothing to do with wheel size. It is specifically and exclusively the ratio of teeth between drive sprocket and chainring, as in 38/16 = 2.375 or 42/17 = 2.471 whereas 36/16 = 2.25. If you think about it carefully, the power that goes into the box is localised at that point by this ratio, regardless of the rolling radius of the wheel. The wheel size selected is thus a "free multiplier".

Andre Jute
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: julk on July 21, 2012, 12:15:00 PM
Dan,
I have ridden the basic 38x16 combo for 4 years (bike stolen) then a further year, because that was what SJS were fitting as their basic recommendation.

I am 65 years old and fairly fit still.
I ride with a 20-30 kgs load quite often, camping or shopping.
I pedal at around 80 revs a minute and was finding gear 10 the most comfortable for level loaded riding.
I have tried but never found gear 1 usable, I would get off and walk at that stage on a hill!

I seem to be the odd man out here, or possibly more reckless, as I have now moved to 43x21 to get gear 11 to be what suits me best. I still do not use gear 1 although I have used the new gear 2 on a recent fully loaded ascent of a 'wall of death' type hill until common sense prevailed and I got off and walked the rest.

Moving to the larger cogs was expensive and I also needed a longer chain. I suspect I will see less chain wear now but not enough to recover the extra costs. I was surprised to see some wear on the 16 cog after just a year and a couple of thousand miles use.

I would suggest going with the lowest recommended 40x17 and running the hub in.
By that time you will have confirmed your choice or have a good idea of what to change to.
Julian.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on July 21, 2012, 05:32:53 PM
Hi Julian!

Very helpful comments, as well; thanks!
Quote
I am 65 years old and fairly fit still.
I saw the pics of your last tour, and you are indeed fit! Well done!

Your post, along with Andre's and a few others interests me in a different way, too -- It seems people do fnd themselves getting stronger after "Riding Rohloff" awhile and begn to use the lowest gears less often than at first. This puts paid to the idea of greater friction, and it may be the Rohloff's gearing and shifting encourage more riding (and perhaps more frequent shifting which also encourages more riding), and so greater fitness. A nice positive-feedback loop.

It really helps to hear how the gearing you chose works with the weights you carry, too. Groceries and camping gear are both loads that have to be hauled, so very useful data for me.
Quote
I would suggest going with the lowest recommended 40x17 and running the hub in.
By that time you will have confirmed your choice or have a good idea of what to change to.
Yes, this is good advice and is confirming my thoughts for a "starter setup". Once I get some distance on the bike, I'll better know my needs in practice and can always make an adjustment with either the chainring, the cog, or both.

The more I read, the more I think it is probably a good idea for me to go with a basic setup, get the gearbox well broken-in, and then reassess my needs and make adjustments as necessary, just as suggested. This gives everything a chance to wear-in nicely, keeps the warranty in effect, and allows me to learn what I need while still having a combination that will be usable in a very broad range.

Fantastic help, everyone; thanks so much. Still looking forward to fresh posts on the topic. As a Rohloff newbie, and I suddenly realize these are the very things I've always wondered about. Learning more brings the picture into clarity.

All the best,

Dan.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Relayer on July 21, 2012, 05:50:10 PM
So, I'm hoping some of you might be kind enough to post your combo and perhaps a comment or two on...
1) How is the low working for you in your conditions/use.
2) Is the direct-drive Number 11 gear working out to be your most-used, or have you compormised on that to get the low/high you'd like?
3) How important has placement of the 7/8 split been to you?

I run 42 x 16 on my RST.

1)  I use gear 5 for an extended 10% gradient, seldom below gear 3 which does for about 15% gradient, and I know of only one hill where I use gear 1 which is somewhat over 15%. My Garmin only reads gradients up to 15% then it goes blank.

2)  I don't know if 11 is my most used gear, but given I do the vast majority of my cycling in 8 - 14 (by design) then it may well be.

3) the 7-8 split is very important since I prefer to remain in 8-14 for most of my riding, I can start off from stationery on a reasonable uphill slope in gear 8 - otherwise on level I start off in gear 9.

With regards to this last, it seems best to consider "high range" (8-14) as the most-used cruising range, and the "low range" (1-7) as just that -- for slogging along at lower speeds, climbing hils, plowing through mud, going into headwinds, and so forth, with Gear 11 as the most-used direct-drive. 

That is exactly the way I see it.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on July 21, 2012, 07:13:37 PM
Quote
My Garmin only reads gradients up to 15% then it goes blank.
So do I, Jim, so do I!  :D

Yes, this helps greatly, too.  (Special note to Andre: I think I am beginning to "get it"; there's hope, I'm trainable, and your patience may yet be rewarded).

42x16...I'm now beginning to wonder if I might eventually "move up" from an initial 40x17 to something higher with use and practice, rather than down. Time -- and use -- will tell. I am so looking forward to seeing how the Rohloff combos compare to my derailleur offerings in practice, and have "budgeted" a good-long time for evaluation. It's only fair, given the nature of the hub and how it differs from what I have experienced to date. It now seems entirely reasonable that one might own essentially two Rohloffs -- one during the break-in period (during which time the owner also "breaks-in" to the idea of this IGH), then an indefinite long-term period (the rest of ownership) where the hub becomes more and more transparent to the user and use becomes second-nature.

Coming to this from the derailleur world, I had already prepared several little 1-14 "gear charts" for my handlebars, depending on the gearing I would choose...which I think I am going to toss in the rubbish. A gear chart just isn't needed (Yes, Andre, I am beginning to see what you meant). No cross-chaining, no "forbidden" combos, no double-shifts and loss of forward momentum to get from the gear you're in to the gear you need.

Ah.  ...Ah!

Best,

Dan. (the light is beginning to dawn...)
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: JimK on July 21, 2012, 07:28:20 PM
No cross-chaining, no "forbidden" combos, no double-shifts and loss of forward momentum to get from the gear you're in to the gear you need.

Yeah, you probably already know from previous experience what bottom gear you need, and that's about the end of it. Nice even regular steps up from there. Simple, elegant.

Stopping and starting on hills is great. I too find it very difficult to get going in 1. So I move up to 4, push hard for a few strokes to get a bit of momentum, then switch back down to 1 to get back to grinding up the mountain. I down to maybe 2.5 mph for the real slogging.

Around here it can be steeply uphill for 50 yards and then steeply downhill. With derailleurs I would be switching both front and back and would barely get the chain settled down before I needed to switch again. When I am exhausted my brain works even worse than usual and I would get really frustrated and constantly get the chain crossed etc. With the Rohloff it is really simple. I can switch from e.g. 3 to 12 in just a couple twists of the wrist, with maybe a couple pedal strokes along the way in whatever intermediate gear I find myself in.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: triaesthete on July 21, 2012, 08:38:43 PM
There are some practical upsides to smallish chainrings and sprockets:

More ground clearance when straddling kerbs or going down a few steps, or lifting the bike over rocks.

Smaller gaps between chain and chainstays to swallow up trailside vegetation.

Shorter chain and less teeth so less to clean and lube. (Lighter too ;) That one is for Pete ;D),

Less vertical drop for the chainring into the trajectory of all the crud thrown up by the front wheel.

Less is more?
Ian
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on July 22, 2012, 01:26:18 AM
There's an additional small complication with the gears. If you want a chaincase or may ever want one, only certain combinations of gears will fit. Since Rohloff gear sets are expensive items, you don't want to throw out a half worn gear train when you fit a chain case.

There are some long articles on the forum in which I detail ten or twelve years of experience with all the major types of chain case. They can all be summarised as, "The only chain case Andre will now recommend is the Hebie Chainglider," among other reasons because it is the least fragile in utility/touring/commuter service. But the Chainglider works only with certain cogs and certain tooth counts on the chainring. (The modular Chainglider adds nothing to this; it's purpose is to adapt the casing to different lengths of wheelbase; it is just a different way of marketing the same parts.)

It's a niggling detail but it is something to keep in mind. I must sleep now, but tomorrow, if you haven't looked it up yet, I can check my records for the permitted Chainglider combinations. I do however remember that 40 tooth chainrings are not catered for. (38, 42 and 44 are permitted, IIRC.)

Andre Jute
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on July 22, 2012, 01:43:11 AM
Andre!

I dont' want to keep you up any later, but (for morning) I can tell you the Hebie Chainglider -- and your account of it on this forum, and comparison to other chain cases including the Utopia -- looks ideal for my needs. It would be especially nice, it would seem, in the desert playa, where it would greatly protect the chain from the talc-like dust wheb dry, and the clay-ike goo when wet.

However, I hestitate due to several impediments that worry me --

1) The potential for noise in use. I like my bikes as quiet as possible, and I am concerned a chain case that effectively glides over the chain might also be noisy. It'd be kinda neat of it sort of "hovered" over the chain instead.

2) The difficulty in getting a good fit for the gearing combos I might find best.

3) This link, right here... http://yacf.co.uk/forum/index.php?topic=43859.0 ...where allusion is made to the Hebie Chainglider damaging Rohloff hubs. Apparently, their construction (perhaps glass-filled and therefore somewhat abrasive?) can ride directly on the side flange of a Rohloff and, with time, cut through it like a lathe.

That would not be good.

Andre, what are your thoughts on these concerns, and what suggestions do you have for overcoming them? I'd like to see a Hebie Chainglider in my future, but I am a bit worried. I'd hate to slice the end off the Rohloff like so much dry salami.

Best,

Dan.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: il padrone on July 22, 2012, 02:48:52 AM
The hub damage from a Hebie Chainglider was a very real problem (http://www.rohloff.de/en/service/faq/faq_detail/archive/2007/27/february/article/Hebie_Chainglider_for_SPEEDHUB_50014_Typ_350_SPE-1/index.html).

(http://www.rohloff.de/uploads/pics/Chainglider_Gehaeuseschaden_03.jpg)
That groove to the left of the sprocket..... should not be there  :o


Hebie now have a model of the Chainglider that has been specifically redesigned to suit Rohloff hubs and not cause any damage.

Problem solved.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on July 22, 2012, 03:05:26 AM
Quote
The hub damage from a Hebie Chainglider was a very real problem.
 
:o

Man alive, Pete!

This is *exactly* what I had feared, but my mental picture was not quite so...vivid.

Yikes!

Best,

Dan. (whose nightmares will now be based on the above photo)
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: il padrone on July 22, 2012, 04:00:02 AM
Yes, it's pretty grim. However the description of damage as:

Quote from: Rohloff
scratching marks occasionally appeared on the hub case by the grinding touch of the Chainglider's rear side

does not seem to gel with that groove.... unless the smudges on the shell are the scratching and the groove is the join between the sprocket and the shell. I had a look at mine and it does not have such a pronounced groove. Puzzled.

Whatever the case the key thing to appreciate is:

Quote from: il padrone
Hebie now have a model of the Chainglider that has been specifically redesigned to suit Rohloff hubs and not cause any damage.

http://www.sjscycles.co.uk/hebie-chainglider-for-rohloff-15-17t-for-38t-black-prod22354/
http://www.sjscycles.co.uk/hebie-chainglider-for-rohloff-15-17t-for-42t-black-prod19788/
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: martinf on July 22, 2012, 07:28:02 AM
I seem to be the odd man out here, or possibly more reckless, as I have now moved to 43x21 to get gear 11 to be what suits me best.

43x21 would probably suit me well - I make that a 77" top with the tyres I use, which corresponds roughly to the highest gear on the Nexus Premium 8 I am currently using to test handlebar setups on my old bike (44x24, so 25" to 76").

As I "spin" short 150 mm cranks, the 76" gear is high enough for me in most situations. It corresponds to 33 kph at 90 rpm and I can push the speed up to about 45 kph for short periods, for example if I need to accelerate to keep up with traffic on a large roundabout.

But I am not too bothered about the warranty on the Nexus, whereas the Rohloff is a much bigger investment. And as I managed with 18" in the Picos de Europa, the 17" low with the "legal" 50x21 setup will be sufficient, although I wouldn't say no to even lower gears and might replace the 50 with something smaller once the hub has passed the initial running-in period.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: NZPeterG on July 22, 2012, 09:49:35 AM
Well my last Rohloff I run 40T to 17T and i'm going to run the same again on My new Nomad (which turned up this afternoon)

Pete..
 ;)
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: il padrone on July 22, 2012, 11:01:51 AM
Danneaux's already posted that link, but Hebie have designed a version specifically to suit Rohloff IGH.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Cambirder on July 22, 2012, 11:05:40 AM
I live in flat Cambridgshire and have gone with 44 x 17 with my RST. On the flat I tend to used 12 & 13 most. In the rolling terrain of north Cambs, Essex and Suffolk I seldom use anything below 7 so in theory I could up my gearing significantly, however from time to time I venture north. I found my current set-up is good enough to tackle the 20% gradients I encountered in the Yorkshire Dales (so far the only time gear 1 has been used in anger) so I will put up with the odd fast decent which has me spinning out at around 45 kph to allow me to get up the odd big hill I encounter on my travels, especially as I want to get some AAA audax points this year.

I know gear 11 is supposed to be the most efficient but in practice it think it makes little difference if you spend most of your riding time in another gear.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Cambirder on July 22, 2012, 11:09:03 AM
How about going down the belt drive route Dan?
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: il padrone on July 22, 2012, 11:33:35 AM
Don't confuse the poor man! Besides, belt-drive will require cutting through the Nomad's fine strong seat stay to instal a coupler.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on July 22, 2012, 04:55:06 PM
How about going down the belt drive route Dan?

LOL! Robin Thorn will organise a shooting party all the way to Portland!
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on July 22, 2012, 07:28:24 PM
Andre!

I dont' want to keep you up any later, but (for morning) I can tell you the Hebie Chainglider -- and your account of it on this forum, and comparison to other chain cases including the Utopia -- looks ideal for my needs. It would be especially nice, it would seem, in the desert playa, where it would greatly protect the chain from the talc-like dust wheb dry, and the clay-ike goo when wet.

However, I hestitate due to several impediments that worry me --

1) The potential for noise in use. I like my bikes as quiet as possible, and I am concerned a chain case that effectively glides over the chain might also be noisy. It'd be kinda neat of it sort of "hovered" over the chain instead.

2) The difficulty in getting a good fit for the gearing combos I might find best.

3) This link, right here... http://yacf.co.uk/forum/index.php?topic=43859.0 ...where allusion is made to the Hebie Chainglider damaging Rohloff hubs. Apparently, their construction (perhaps glass-filled and therefore somewhat abrasive?) can ride directly on the side flange of a Rohloff and, with time, cut through it like a lathe.

That would not be good.

Andre, what are your thoughts on these concerns, and what suggestions do you have for overcoming them? I'd like to see a Hebie Chainglider in my future, but I am a bit worried. I'd hate to slice the end off the Rohloff like so much dry salami.

Best,

Dan.

First of all, forget the Utopia Country chain case. It won't see out a day of cross-country service. It is made stupid-light, including in some of the permanent parts. Also, you might have difficulty getting the necessary consumable service parts; those four bellows are not supposed to last longer than a year, and they won't last a day in contact with any desert flora.

Secondly, forget the Dutch plastic chain cases. Those are big, and noisy, and vulnerable to stones. I wrecked two against lampposts. They're also heavy. Metal in that design might survive a few years but the weight and the noise... Forget it.

Really, the only chain case you should even consider is the Hebie Chainglider. It's flexible, small, relatively light, and tougher than old boots. It is also a superior design, intrinsically, theoretically, and in practice, as well as in execution, to any of the others, including the traditional Dutch styles. By a mile.

To answer your specific questions, there is no additional noise from the Chainglider. The article quoted in this thread was written by someone who most likely has never used a Chainglider;' it reads like street corner gossip. Noise from a CG is an indication that it requires to be adjusted, and even this noise is a faint whirring. You adjust the Chaingilder until there is no noise, by adjusting the length, pushing the arms in differentially to the sprocket cover. (No, those ridges are not saw guides, they're locks.) I don't know quite how it does it, but it appears that the rear fitting holds the main run of the Chainglider clear of the chain.

My experiment with running a chain in only the factory lube without extra oil takes on additional importance here.

(http://www.coolmainpress.com/miscimage/kmc_x8_sm_factorylubeonly_700km_hebiechainglider_clean_inside.jpg)

That Chainglider isn't new, it's done 2700km. It was last cleaned 700km earlier when the zero extra lube chain experiment started.  I think we must conclude that, if the CG were to rub against a chain, without lubrication, there would be markings after a 700km. There aren't. Refer to the photo. It now stands at over 1100km without extra lube, but I had it open a couple of weeks ago and there was no point in taking photographs as it looks the same.

I don't see your problem with a good gearing solution. You can, from memory, have any of the 15, 16 or 17 tooth cogs. You can choose among chain rings with 38, 42 and 44 teeth. You have to decide whether huge diameters of toothed rings for the same gearing will give you greater longevity or lower cost per mile than covering smaller diameter gears. I think you will find it no contest, and the Chainglider's tendency to eliminate maintenance will be a very strong additional benefit.

The Hebie Chainglider may once have scratched some Rohloff hubs. But the sprocket cover has been redesigned since then so that there is now a specific Rohloff rear end to the Chainglider, and that problem is long solved. I just now also made a visual inspection of my Rohloff hub, on which the Hebie Chainglider has run over 3000km, and there's not a scratch on it.

The real problem with the Hebie Chainglider for you, in particular, is not noise, gearing, or casing damage. For 11 months in the year, I can just about guarantee, from experience, that a Chainglider will be a superior solution for you, whatever you do, to a bare chain. (Ditto for virtually all the other posters here. I'm absolutely amazed at the resistance.) But in the other month, when you go into the desert, a problem may arise. It is whether the Chainglider will fully exclude the fine dust in which you ride on your desert tour. It seems to me at least possible that the fine dust will enter through the opening at the sprocket end, and form a grinding paste with any wet lube you use inside the Chainglider, which from there will spread through out the tube it forms, which elsewhere is pretty well sealed against itself. I have no way of telling whether this is a real possibility; the Chainglider shrugs off my lightly dusted roads, and rain too, as you can see in the photograph where the outside of the Chainglider and the bike has a fine film of dust, and the mudguard shows splashes of wet, yet the inside is pristine; not exactly a tough test!

Andre Jute
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: martinf on July 22, 2012, 09:25:52 PM
Really, the only chain case you should even consider is the Hebie. It's flexible, small, relatively light, and tougher than old boots. It is also a superior design, intrinsically, theoretically, and in practice, as well as in execution, to any of the others, including the traditional Dutch styles. By a mile.

Interesting. I considered a chaincase for my 5-speed hub geared commuter more than 10 years ago, but ended up rejecting the idea as too much hassle to fit a Dutch-style chaincase to my existing bike.

More recently, when first considering a new Rohloff-equipped Thorn in 2006, I asked SJS Cycles about chaincases and they basically said they didn't advise them, partly because they thought there might be problems using the eccentric bottom bracket.

Even more recently, I found the Utopia (too expensive for the claimed service life) and Hebie. I was put off the Hebie when I found the information about the non-specific Rohloff design damaging the hub, this has obviously since been sorted with the Rohloff-specific version.

Any idea what the service life of a Hebie Chainglider might be?

Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on July 22, 2012, 10:15:24 PM
Hi All!

I'm terribly pressed for time today, so I can't participate or reply as I'd like till tomorrow, but Martin raises a very good point I'm hoping you may be able to amplify and address, Andre. Namely...
Quote
I asked SJS Cycles about chaincases and they basically said they didn't advise them, partly because they thought there might be problems using the eccentric bottom bracket.
Andre, does having an eccentric BB with a range of motion affect the Hebie Chainglider's fit?

Thanks, everyone!

Best,

Dan.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on July 22, 2012, 10:30:11 PM
Any idea what the service life of a Hebie Chainglider might be?

No idea. Mine's getting on for two years, and if I scrubbed it up, I could probably sell it as hardly used. Certainly it will be much longer than the service of the Utopia Country, and even a well made Dutch plastic chain case. The Chainglider seems to me well conceived, designed and made.

Andre Jute

Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on July 22, 2012, 10:47:44 PM
Andre, does having an eccentric BB with a range of motion affect the Hebie Chainglider's fit?

I don't see how. It sounds like one of those street myths in the general resistance to the whole idea of a chain case.

The Hebie Chainglider fits to any wheelbase length by inserting more or less of the tubes carrying the chain into the sprocket cover, which also locks the assembly.

The Hebie Chainglider is therefore specifically designed to adapt to several lengths. It doesn't matter whether the variable depth is wheelbase length or EBB adjustment.

What's the range of movement of the eccentric bottom bracket, 15mm? Even for twice that, you just move the Chainglider arms in and out. Original setup should be about the middle of the range of adjustment. In the slotted axle hanger Rohloff designed and advises manufacturers to use, the Rohloff box can move near enough an inch backwards and forwards, and it makes no difference to the Chainglider.

As for the vertical movement that the EBB imposes in part of its adjustment, it's irrelevant because Hebie's Chainglider, uniquely, is nowhere attached to the bike. The entire assembly will just rotate fractionally around the sprocket.

Andre Jute
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on July 22, 2012, 11:00:42 PM
A tremendous help, Andre; thank you!

I agree, the Hebie Chainglider sounds the stuff of my dreams except for touring on dry desert playa. Last trip through in the car, I came home and found it had even sifted in to fill the interior of the taillights. The lenses are glued solidly in place, and the bulbs are gasketed with dense foam, under trim panels accessible only via the car interior. The stuff silts and sifts everywhere and even seems to condense in quantity from whatever is floating in the air. This corrosive alkali is the stuff that makes my lips and nose bleed after a couple days' exposure. It is an order of magnitude worse than the ashfall we received from Mt. St. Helens' eruption in 1980. You're absolutely spot-on as to what would happen if it entered the chain case, and -- yes -- mine is not the usual situation, where I am sure it would work fine.

I can easily see myself with a Hebie Chainglider for all ordinary use (yes!), to be removed for my tours (replaced with a crank-mounted bash guard/chain protector), then reinstalled upon my return. That would give the best of all worlds while avoiding problems in one unique environment.

Wonderful responses, more than I could have hoped for.

All the best,

Dan. (oh-so-pressed today, but checking on things here when I can)
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on July 23, 2012, 12:50:17 AM
Another question or two, Andre, since the Hebie Chainglider (which I am more and more tempted to purchase) determines gearing and vice versa...

How difficult/quick is removal and replacement in the event of a flat tire?

I realize you've set your bikes up so flats simply.do.not occur, but for those of us more likely to incur flats (via goathead thorns, if nothing else), is a wheel-change still an easy process? At least compared to a flat on the rear of a derailleur bike? Thinking about the process (but not having done it) on a bike with the Rohloff EX box, you'd have to...
1) Open the brakes if your tires are wide.
2) Disconnect the EX box via the thumbscrew.
3) Unsnap the (maybe entire) Hebie Chainglider.
4) Throw the q/r and drop the wheel.
Installation would be the reverse.

Andre, I have to ask again, given my mania over having a quiet bike...is the Hebie CG objectively quiet? Can you somehow quantify for me the extra noise it produces, if any? I just don't want to have to hear the boggita-boggita-boggita* of the chain links clattering on some sort of internal plastic knob, though I can't imagine how they possibly could, given your case shows no wear.

[*When I had my own car-repair shop years ago, I would encourage customers to imitate the noise that caused them to seek service; made it far easier to find the problem. A number were quite good at it, and often supplemented the noises with gestures. I am but an amateur.]

Andre, your wonderful writing skills combined with your great enthusiasm and a keen, analytical mind make me reach reflexively to draw out my wallet. I realize you've tested the Hebie Chainglider extensively and carefully looked for and noted any possible shortcomings, and you surely gave me a good steer on the SKS pump, for which I am very grateful. I ask the above not in doubt but because getting one of these things is Real Money to me, and I have to be um, "careful" (thanks, Ian).  As for the desert, I figure I can either swap before the trip for a pie-plate bash guard, or possibly even remove the Hebie CG and carry it under my my load straps in the dustier portions. Remember, I ride from and back to my front door, so often there is as much as 300 road miles/480km before I hit the really silty stuff, and I use generous mudflaps to extend the mudguards.

Thanks for your patience with me.

All the best,

Dan.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on July 23, 2012, 03:31:34 AM
Let's deal first with the noise, since that would be a deal breaker for me too; I'm sensitive to noise and to vibrations in my hands. (A writer is a sort of manual worker; he operates a keyboard.) Any noise in a Hebie Chainglider setup is indicative of a maladjusted Chainglider. The noise, when the Chainglider is maladjusted is exactly what you would expect, a sort of whirring sound between chain and Chainglider, but at a much lower level than you would expect. The Chainglider material is thicker than it looks in my photograph, which doesn't make the bevelled edges quite clear, and it isn't resoundingly hard like the Dutch plastic cases (nor soft like rubber) but resilient, probably loaded with fiberglass so that it dampens sound. But, most of all, it fits very tightly together over the run of the chain and even over the chainring, though less so over the sprocket, but it matters less there because the central hole is pretty small and behind tubes and rack legs and other transmission fittings, so that very little sound escapes.

A well adjusted Chainglider is silent, period.

If you have a flat, first disassemble the Hebie Chainglider as far as you need to. This is not a big deal as long as you remember to put the smallest part, the external clip at the front of the chainring, in a deep pocket. The parts pull apart easily with your fingers. If you have a magic link, maybe you can get away with taking off only the sprocket cover; I consider it rather unlikely. But you don't take the whole Chainglider off. I normally leave the pieces hanging, and it has done no harm. You won't damage the thing unless you try very hard. The reason for the further disassembly is to get the chain off the sprocket; the Chainglider is such a close fit, even with the sprocket covers off, it works against you here. But we're talking about twenty seconds, once you've worked out how far you need to go. Same for reassembly. Everything just clicks together with the German precision innocents expect to find in the Rohloff gearbox controller...javascript:void(0);

That done, disconnect the EX box which is fast (putting it back can be a pain until you learn to use one hand to wriggle the rotary gear change control ever so slightly so you can get the EX box onto its two pins and the correctly aligned on the searching shaft), squeeze the flat tyre past the brakes, and drop the wheel out. Even with 32mm wide rims, I've never had to adjust the brakes to get the wheel out; in general, tyres are so much wider than the rims that having to fiddle with the brakes smacks to me of poor design.

None of this adds appreciably to the time it takes to fix a flat, unless you're racing, in which case you might begrudge the 30 seconds (twice, disassembling and fitting up again) taken by the Chainglider and the EX box thumbscrew, at least until you've had some practice.

The insidious dust you describe will definitely combine with the oil, and inside the tight confines of the Chainglider grind your chain, and probably your chainring and sprocket too, into submission. Every other chain case known to me will let in more dust, but it's an irrelevant observation, as any chain case would be more dangerous to your transmission than its absence.

I see no problem carrying a Hebie Chainglider under straps, but it's a pretty big, awkward, even obstructive thing. You won't manage to fold it. I think for that month in the year you will have to do without.

Andre Jute
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on July 23, 2012, 03:43:40 AM
Andre,

This is an outstanding response, and -- I am sure -- appreciated by far more people than just myself.

Thinking back to my thread on long-lived parts, if this thing works for me anywhere near as well as it does for you, it will quickly become an "essential" in my cycling. And, I agree -- best to leave it off for the hardcore desert touring. For those trips, I will simply fit a "pie-plate" or bash-guard style chainring protector, then swap back to the Hebie upon my return. I have watched the movie at http://www.hebie.de/Chainglider-350-38-42-44.hebie350chainglider.0.html so many times, now, I think I could put one on or take it off in my sleep.

I know you know noise and sound -- you've got the audiophile background to more than qualify -- and if you say it's quiet (provided it is properly assembled), it's going to be quiet.

As for the tire repair/wheel change angle, you've completely satisfied me on that score as well. Keying off your description, I recently read of a clever additional theft-prevention technique for Rohloff-equipped bikes: 1) Shift into 14th. 2) Remove EX box. 3) Shift back to 1st gear. This leaves the bike stuck in 12th, making it difficult for a thief (who presumably would have spent time already disabling the locks) to ride away quickly. Sounds promising as an additional layer of defense. In my case, I'll have the ring-lock and its cable as well as the Pitlocks (yes, I will go for some; it seems unlikely people in the small towns I pass through will be familiar with them) and motion-sensing alarm to deter theft.

Thank you again, Andre; you're doing a real service for those of us who have so often wondered about chain-cases and wished for the near-'nuff perfect solution.

All the best,

Dan.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: il padrone on July 23, 2012, 10:43:15 AM
Reading your review and extra comments Andre, I'm glad I ordered the Hebie Chainglider for Rohloff yesterday  ;D Should be really good for chain wear,and it will get comments from my cycle club mates  :-X

"What next.... clogs?"   ;D

(http://static.flickr.com/2238/2194427487_4efa0420d8.jpg)



Re. dust. I don't see that the chain in a Hebie will get any worse than a chain out in the open with all that dust. My chain on the Oodnadatta Track got pretty dusty. I just had to wipe and lube it every couple of days.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on July 23, 2012, 11:55:04 AM
Hah, but was the statuette the elegant gentleman won as well-dressed?

Dan's playa dust is special, a sort of sifted concrete.

I've even demounted tires after a trip -- ones that were never underinflated or flat -- and found the dust had entered the rim through the spoke holes, then migrated around the tube to coat the inside of the tire casing.

When the stuff gets damp -- after a rain or near the "shoreline" of a dry lake -- it becomes...well, it turns to a grey, clayey goo that literally paints whatever it comes in contact with, and it doesn't come off.

In the close confines of the Hebie I think it will, with the oil, grind the chain into nothing, or if it runs out of oil set it solid, as if in a tight tube of concrete. Either could be a disaster. I don't imagine Dan carries a spare chain, and anyway, the chainring and sprocket would also be stuck to the chain. The playa may be one case where a big ole Dutch chain case, with extra holes drilled in the bottom to let the dust out again, may be superior to the Chainglider. (Not advising it, eh, Dan; those plastic cases won't take the slightest rough riding.)

Andre Jute

PS The comments from your club mates could be, "Sissy!" and "A real cyclist has oil on his legs."
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: il padrone on July 23, 2012, 12:11:20 PM
How difficult/quick is removal and replacement in the event of a flat tire?

I realize you've set your bikes up so flats simply.do.not occur, but for those of us more likely to incur flats (via goathead thorns, if nothing else), is a wheel-change still an easy process? At least compared to a flat on the rear of a derailleur bike? Thinking about the process (but not having done it) on a bike with the Rohloff EX box, you'd have to...
1) Open the brakes if your tires are wide.
2) Disconnect the EX box via the thumbscrew.
3) Unsnap the (maybe entire) Hebie Chainglider.
4) Throw the q/r and drop the wheel.
Installation would be the reverse.

One thing about the Chainglider is that it may assist with one of the shortcomings of the Nomad. One thing missing from the frame that would be valuable when wheel changing is a chain hook on the seat stay. Without a jockey cage tensioner the chain simply slumps to the ground when you take the wheel off.... into the dust and grit  :( .

With the Chainglider you may be able to remove the wheel by just removing the rear section. In that case the sections along the upper and lower runs of chain would help to hold the chain up and protect it from any ground contact. Bonus!
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: martinf on July 23, 2012, 02:03:23 PM
Thanks André.

Looks like the Hebie Chainglider does solve most of the problems raised by chaincases with a Thorn Rohloff and other bikes not designed from scratch for chaincases.

No way any of my local French shops will stock one, but they are available mail order from Germany at http://www.roseversand.com

I think I'm going to get one rapidly to try out on my 5-speed - that has 44x21, so ought to be directly compatible without having to change sprocket or chainring.

And not too expensive at 28.5 Euros for the appropriate front and non-Rohloff rear bits. The Rohloff version naturally costs a little more.

For Rohloff, the listed compatible chainrings and sprockets are 38, 42 or 44T  with 15, 16 or 17T.

The 38x16 combination is the lowest "legal" option, and is equivalent to the 50x21 I was thinking of getting. And from the information on the Rose site the rear Chainglider is the same for 15-17 so I could change the gearing to 38x17 later on without having to change the chaincase.

I don't go anywhere near alkali deserts, but here in Brittany and down the west coast of France we have a lot of sandy cycle tracks. Sand plus rain is a good recipe for quickly wearing out an unprotected chain.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on July 23, 2012, 02:34:26 PM
I hope Hebie knows where to send the cheque!

I used to be in advertising and my erstwhile associates will turn in their graves to hear that I give such good word of mouth free of charge...

Andre Jute
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: sg37409 on July 23, 2012, 11:17:15 PM
40*16 with a 26*1.6 tyre. I chose these with gear 11 in mind, and have found myself in 11 mostly, 10 if its windy or I'm tired. I thought gear 11 would be important due to the draggie-ness of the rohloff, and I think thats a very minor factor even when new. I reckon I was over concerned about it, though this may be due to the fact I'm content to pootle along on the rohloff rather than "training" on the racer.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: gearoidmuar on July 25, 2012, 08:49:18 PM
When I bought my TRT it had 40x16. I found this a little bit too low at the upper end and I found having to keep the chain/cog in sync when I changed the wheel a nuisance.
When they were worn I changed to 42x15. For me this is perfect. I'm 62 and 15st and tour a lot but not with a huge amount of luggage. Usually 30lb max. I would go for a 42x17 except that the high gear would be too low for a bit of fast stuff.
I think that the TRT with Rohloff hub is just the best thing ever. I've had maybe 3 dozen or more bikes in my time and this is the most satisfactory.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: swc7916 on July 26, 2012, 05:50:50 PM
Most of the people here sure gear their bikes low!  I can't imagine needing gearing in the 'teens and losing my top end.  The gearing on our tandem is 50x15; with 26x1.25 tires this is equivalent to a gear range of 23 to 122 gear-inches.  This is an improvement over our derailleur tandem which has a range of 25 to 120 gear-inches.  When we need gear 1 for climbing, our speed is about 4-5 mph; it would be hard to stay upright if we were going any slower than that.  On downhills we frequently exceed 30 mph and occasionally reach 45+ (mid-40's is my stoker's limit.)

On the subject of chaincases:  As a cyclist and resident of the Pacific Northwest, you would think that these would be particularly beneficial here, but I've never seen one.  Besides, they look like a PITA.  Chains are cheap and tandems go through them so fast that I can't see that a chaincase would be worth the trouble.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on July 26, 2012, 06:49:30 PM
Quote
Most of the people here sure gear their bikes low!  I can't imagine needing gearing in the 'teens and losing my top end.
Well, yes! But...
1) You are able to pull high gears without injury (like Jawine, who does this regularly as well).
2) You have great knees (also like Jawine and unlike me, who donated mine to a car accident while in high school).
3) I greatly admire you, Jawine, and Jobst Brandt for 1) and 2) above. Perhaps in my next life, I'll do it too.  :D

Meanwhile, it is "gear low and pedal like a hummingbird" with a light, fast cadence for me, never dropping below 80RPM under load, 60RPM at worst. If I do that, I'm fine with no complaints.

You make a very good point about diminishing balance returns at low speed. For years, I did trackstands at traffic lights while commuting (till a police officer issued me a USD$50 ticket, arguing a single-track vehicle could not truly be balanced at rest without toppling; therefore, I must be moving and had run the stop sign though I was well behind it at the time he collared me), and that may have helped with the low gear-balance thing. I find I can manage okay fully loaded on 16-24% hills down to 2.5mph/4kph before dabbing a toe, but that's it. I've got the tandem geared with a 46x13 high (92") and a 22x28 low (21"). Yes, we spin-out pretty quickly, but the last time I had my father on the back (age 87 at the time) we still managed 63mph down a local hill with the Arai drag brake lightly on. Would have been more if the light at the bottom of the hill had stayed green; Dad was disappointed, as he wanted to go for 65 or even 70 (former motorcyclist who also donated his knees to a youthful car accident in which he broke his cervical vertebrae. We bounce well).

Quote
On downhills we frequently exceed 30 mph and occasionally reach 45+ (mid-40's is my stoker's limit.)
Above 45, does your stoker do the kidney-pinch thing? I've had some that did...! Not Dad or Sis, but Others.

Quote
On the subject of chaincases...I've never seen one [in the PNW]
They're pretty rare down here in Eugene, too. I recall seeing a couple on bikes brought by Dutch students at the local uni, but that's about it. They just don't seem to be on anyone's radar.  I think there may be a perceptual barrier to overcome. Be ideal for commuting, so that's where we might see them first, introduced by a company like Civia, whose offerings already sport top-run covers.

Steering the ship of discourse back toward Rohloff gearing, I have decided to go with 40x17 (and a pie-plate/bash-guard protector) on the Nomad. I had planned to go with 38x16 to allow for a Hebie Chainglider, but I think it best to go with the Thorn default spec for now to allow the hub to break in at the usual rate. I can always adjust gearing at some point in future, but this will give a great, standardized start for this Rohloff newbie, and the low will be low enough for my loaded touring at 17.1". The high is 89.8, which is the stuff of my dreams on the flats but might see occasional use screaming downhill. One of the really nice things about this choice is it puts Gear Eleven at 61.2, and either 58 or 62 gear-inches are my favorites for cruising on flats, so will see lots of use. I figure with time and familiarity, I will gain a better idea if the Rohloff needs further adjustment.

Oh! Nix on the Chainglider for desert touring for the very reasons Andre cited -- the sifting, silting talc would get inside and wreak havoc, and I have great concerns about the possibility for wear on the hub by the chaincase especially in those conditions. I'm going to let Pete (Il Padrone) try his first! ;) Lookin' forward to full reports on using it in your red clay and bulldust, Pete.

Best,

Dan. (who thinks good knees may be a Super Power akin to x-ray vision)
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: swc7916 on July 27, 2012, 04:52:49 AM
In regard to your question about gear 11:  I didn't plan my gearing around 11th gear, I just chose the chainring/cog combination that gave me the range I wanted.  Gear 11 is about 87 gear-inches on our tandem.

Further, regarding the pie-plate bash ring:  We have something like that on our tandem.  Since the bike was built with two single-bike double cranksets, the front had an empty position.  The builder put the chainring on the inner position and for the outer position installed a chainring which, with its' teeth ground off, is the same size as the inner chainring.  it is evident in this photo:

http://www.rodbikes.com/catalog/makeshift/images/makeshift6-5.jpg (http://www.rodbikes.com/catalog/makeshift/images/makeshift6-5.jpg)
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on July 27, 2012, 06:20:44 AM
Hi swc7916,

My! That tandem of yours is something else again -- more gorgeous with each viewing. And...such an elegantly simple drivetrain. That single-side drive with the single 'rings (double on the stoker's crank) with Rohloff is just.so.sanitary.

Wow.

By any chance, is that R&E's wall in the background? It looks a bit familiar from my last visit up there.

Quote
I didn't plan my gearing around 11th gear, I just chose the chainring/cog combination that gave me the range I wanted.  Gear 11 is about 87 gear-inches on our tandem.
swc, do you notice any less effort in direct-drive 11th compared to the adjacent gearing? I figure if a difference is really noticeable, it would be even moreso under a heavy tandem load.

Thanks for the insights.

Best,

Dan.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: fleur on July 27, 2012, 06:49:11 AM
On our tandem, we have 48x15 with 26x2 tires rear, so very close to what swc7916 has (the recumbent stoker has an even bigger ratio 38x34 x 48x15, so something like 53.6x15 with IPS).

We don't feel any efficiency nor noise difference between the highest gears (8-14).  

The lowest group 1-7 is more noisy but its almost impossible to subjectively evaluate if there is any efficiency difference since those gears are only used going uphill and of course riding much slower.

So, I think that it is more important to choose your ratio to be remain as much as possible in the highest gear group than using as much as possible gear 11.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on July 27, 2012, 07:19:45 AM
Quote
...I think that it is more important to choose your ratio to be remain as much as possible in the highest gear group than using as much as possible gear 11...
Thank you Fleur; this helps tremendously, and confirms I have made a correct "initial choice" in gearing the Nomad for my needs with the 40 x 17 combination. My goal was to be conservative and make a selection that will work for my requirements, place my most-used gearing in the upper-tier, and meet Rohloff's recommendations to remain in warranty while still giving the low gear I needed. I realize the hub will go through a break-in period, and it seems worthwhile to give it every opportunity to achieve a good meshing between gears using one of the "legal" combinations.

For me, it isn't just about warranty coverage; I really do want to maximize lifespan and minimize any chance for breakage when I'm away from civilization. With that in mind, anything that ensures a good outcome is worthwhile. That's why I ordered an oil change kit, Oil of Rohloff, and a sprocket remover right away, so I can be prepared to do maintenance on-schedule. It is to my advantage to give it the best chance for success, especially during this early break-in period.

I thought strongly of going for the 38x16 because of the even-numbered tooth combination, but I think wear with the larger 40x17 will give much the same end result, thanks to the larger diameters in play. I plan to keep a close eye on wear by distance traveled to see how things are going. It would be wonderful to do an "A-B" comparison, but there are too many variables to draw any conclusions between different riders. Maybe my next cog and chainring will be a 38x16 so I can compare!

By happy coincidence, the 40x17 combination also places gear 11 to perfectly match my favorite derailleur flat-terrain crusing gear at ~62 gear-inches. 38 x16 would have been nearly identical, so it was largely a matter of going with Thorn's recommendation of a 17T cog and matching the chainring I needed.

I appreciate the input, everyone. Gathering this collective experience is painting a much fuller picture for those of us who have never owned a Rohloff previously and wish to learn as much as possible from afar so we can consider or plan a purchase or just to better understand this IGH. A real service to anyone contemplating this drivetrain. Thanks!

Best,

Dan.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on July 27, 2012, 01:27:08 PM
Oh! Nix on the Chainglider for desert touring for the very reasons Andre cited -- the sifting, silting talc would get inside and wreak havoc, and I have great concerns about the possibility for wear on the hub by the chaincase especially in those conditions. I'm going to let Pete (Il Padrone) try his first! ;) Lookin' forward to full reports on using it in your red clay and bulldust, Pete.

After close inspection of the Rohloff-specific rear end of the Hebie Chainglider on hand of the discussion here, I would have ZERO concern about damage to the outside of the Rohloff box even in the playa. My concerns were about that fine grinding dust getting inside the Chainglider with the oil, and having no way of escaping, but that would damage the chain and sprockets, not the casing.

As described further up the thread, I had more concern about the possibility of the dust getting into the Rohloff box itself were it operated by an innocent/inexperienced/thoughtless/careless/ignorant rider, which isn't you, Dan.

Anyway, I'm one of those people who abhor the practice of collecting things and not using them. I have no objection to the signs of fair wear and even honourable scars  of war on implements meant for hard use. You're not buying a Rohloff gearbox to polish and put in a glass case, you're buying it to use, and a few honourable scars you can point to as you tell the story of traversing a dangerous desert adds to its value for the initiated. (Still, smart to order it anodised in black rather than merely polished plain aluminium.)

Andre Jute
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: swc7916 on July 27, 2012, 07:21:26 PM
By any chance, is that R&E's wall in the background? It looks a bit familiar from my last visit up there.

It's in the alley behind the shop.

do you notice any less effort in direct-drive 11th compared to the adjacent gearing?

My impressions are the same as fleurs'.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: swc7916 on July 27, 2012, 07:32:27 PM
such an elegantly simple drivetrain. That single-side drive with the single 'rings (double on the stoker's crank) with Rohloff is just.so.sanitary.

Thank you.  Most tandemists are confused by the drivetrain until I explain it to them.  First of all they expect a cross-over drive and secondly they expect a derailleur system.  They will look at the stoker's crankset, see two chainrings, and ask if I have a double.  What they don't notice is that there is no front derailleur and two chains, one of them going forward.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: fleur on July 27, 2012, 08:17:51 PM
Thank you.  Most tandemists are confused by the drivetrain until I explain it to them.  First of all they expect a cross-over drive and secondly they expect a derailleur system.  They will look at the stoker's crankset, see two chainrings, and ask if I have a double.  What they don't notice is that there is no front derailleur and two chains, one of them going forward.

The very clean system of your tandem with both chains on the right side is becomming common in Germany where there are many tandems factory equipped with a Rohloff.  I guess there are much less in the States ?
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on July 27, 2012, 08:36:09 PM
Quote
I guess there are much less in the States ?
Yes, fleur, very much so. Crossover drive is the norm with derailleur-geared tandems here in the 'States. It is, however, twice as efficient at making one's legs oily from the chain.  :D

Best,

Dan (who is thinking a crossover chain-case would make a lot of sense)
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: JimK on July 27, 2012, 10:30:39 PM
OK, now this discussion about tandems has got me thinking - which is always a dangerous thing!

The idea behind a minimum gear ratio on the Rohloff is to insure some maximum torque is not exceeded at the sprocket. Some maximum pedal pressure (and crank length) is assumed.

But with a tandem, there are two feet pushing on two pedals... the torque at the sprocket would be double! Shouldn't the minimum gear ratio be doubled to respect that torque limit?

But two riders weigh twice as much... to get up the same hill at the same speed, they'll need that doubled torque at the sprocket!

I seem to have proved that a tandem with a Rohloff needs wheels that are twice as small!

What have I got scrambled???
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on July 27, 2012, 10:37:19 PM
Quote
...has got me thinking - which is always a dangerous thing!
Not at all!
Quote
I seem to have proved that a tandem with a Rohloff needs wheels that are twice as small!
Correct, by all my calculations as well.
Quote
What have I got scrambled?
It's not you, Jim, but I think your/our analysis fails to take into account the healthy safety margin Rohloff engineers into their hubs. (others will hasten to correct -- as they should -- if my assumption is incorrect).

I believe this is why so many people (after a suitable break-in period) are able to get by using "illegally low" gearing without consequence or bad outcome.

Dan. (...think I've got that right...the Dan part is okay; I mean right about the Rohloff safety margin)
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: JimK on July 27, 2012, 11:09:44 PM
"illegally low" gearing

I do get tempted. But I find my lower speed limit is much like what you mentioned recently, 2.5 mph, because of balance difficulty The 38x16 is probably about a 40 or 50 rpm cadence or thereabouts at that speed. Plus I spin-out downhill at maybe 33 mph or so.

I just need a few years to work on my physiology.

(We skipped the New Paltz book buying trip, or rather, we went by automobile. Family life gets complicated!)
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: il padrone on July 28, 2012, 12:26:43 AM
Not at all!Correct, by all my calculations as well.It's not you, Jim, but I think your/our analysis fails to take into account the healthy safety margin Rohloff engineers into their hubs. (others will hasten to correct -- as they should -- if my assumption is incorrect).

From Thorn's "Living with a Rohloff" document:

Quote from: Andy Blance
Rohloff will not give a warranty on the hubs, when a gear, with an input ratio smaller than 40 x 17 is used on a solo bike (42 x 17 on a tandem). However Rohloff say that even “world class athletes” are warranted to use such a gear.

So if you are riding with Lance, Cadel or Bradley, be very strict about the 'red gears'. Otherwise, for us mere mortals I don't think it is a huge issue. Also note - I do believe the torque limit is independent of wheel size. The same gear in a 20" or in a 700C wheel generates the same torque - it's simply that the load and/or the speed will differ.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on July 28, 2012, 12:45:16 AM
Quote
...torque limit is independent of wheel size...
Yep. Andre set me straght on that one. And, it makes sense when you stop to think about it. It is the ratios, rather than the moment arm of the wheel size that determine torque levels internal to the hub.

Best,

Dan.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: JimK on July 28, 2012, 12:51:14 AM
I do believe the torque limit is independent of wheel size.

Ah, thanks for that, showing that Rohloff indeed wants a higher ratio on a tandem, though nothing like double the solo.

Suppose Rohloff did insist on a 80 tooth chainring for a tandem, twice the 40 tooth solo ring. It'd be the devil to get a tandem up a big hill with that! Unless you drop the wheel size down to say 13 inches at the same time! That would bring the overall gear ratio down to what the solo gear was, without, as you say, affecting the torque at the sprocket.

In a week there'll be a race right here:
http://www.tourofthecatskills.com/ (http://www.tourofthecatskills.com/)

The teenager and I plan to ride over to the route with a camera. I hear some of the racers will walk on sections up that big hill. I've ridden it but had to stop a few times to catch my breath. I don't know if we'll be able to get up along there during the race - how much of the road do they block off? That road is not just steep but narrow and sort of half falling off down the cliff...

(http://i140.photobucket.com/albums/r6/kukulaj/edge.jpg)

These are the hills that make me think about lower gears!
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: martinf on July 29, 2012, 08:33:02 PM
I hope Hebie knows where to send the cheque!

I used to be in advertising and my erstwhile associates will turn in their graves to hear that I give such good word of mouth free of charge...

Andre Jute

Chainglider arrived yesterday, it was easy and quick to fit. But I took it off straight away as the chainring seemed to rub when I turned the cranks by hand.

The instructions say chainrings < 3 mm. Mine is a tad wider than that, its a TA Cyclotouriste for 1/8" chain, and the Sedis 1/8" chain is I reckon just under the max recommended of 9 mm.

I measured some other chainrings for 3/32" chain on other bikes (all TA of various sorts), they were no narrower, all a tad over 3 mm, so I thought about the apparent stiffness of a SON hub when you turn it by hand, put the chainglider back on and did a 25 km ride to try it out.

Not completely silent, there was a sort of swishing noise that I think came from the chainring rubbing on the edges of the chainglider, and a very slight grating noise that I think is the chain rubbing somewhere inside. Neither noise is particularly loud, and I think the swishing noise reduced somewhat by the end of the ride. The grating is pretty faint, about on a par with the noise from the tensioner pulley on my bike with the Nexus 8 premium hub.

I reckon there would be less noise with a thinner chainring (steel ?) and a 3/32" chain.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on July 29, 2012, 09:33:51 PM
Hi Martin!

I'm very much looking forward to your extended user reports on the Hebie Chainglider. Already, what you have reported is a vast help.

Robin advised me the chainglider needs a thinner ring, and gave an example:

http://www.sjscycles.co.uk/surly-110-pcd-5-arm-stainless-steel-chainring-38t-silver-prod20828/

I realize the Surly is not compatible with the T/A pattern, 50.4mm* BCD crank you're running, but something to keep in mind. It would be helpful to know exactly how wide/thick the Surly 'ring is for comparision. No doubt Andre can enlighten us on both points, based on his own lengthy experience.

Martin...can you please keep a close eye out for any possible rubbing and abrasion between the right side of the Rohloff hub (just inboard of the cog) and the opening in the Chainglider? This is where I would expect problems to arise...if any. [EDIT: Oops. I realize you're not running it with a Rohloff. Still, all the other information is helpful]

Meanwhile, I have decided to go with a pie-plate/bashguard style chainring cover so I will have no concerns about trapping dust inside while desert touring. Still bvery much looking forward to how these work for others, and also looking forward to your next installment. The photo was an ideal complement to your written report; well done!

Best,

Dan.

*Edit from my original statement, wrt "49BCD". My mind was thinking "Stroonglight 49D" which shared a base crankarm spider dimension with the orginal T/A Cyclotouriste, and somewhere along the way, that thought came out the fingers wrong...happens)
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on July 30, 2012, 02:10:15 AM
... chainring seemed to rub when I turned the cranks by hand...

Not completely silent, there was a sort of swishing noise that I think came from the chainring rubbing on the edges of the chainglider, and a very slight grating noise that I think is the chain rubbing somewhere inside. Neither noise is particularly loud, and I think the swishing noise reduced somewhat by the end of the ride.

Super photograph, Martin.

The noise, and especially the grating, tells us there is something amiss in your installation. I'd check the inside of the Chainglider every 25 miles to see if the teeth or the chain sides are marking the plastic. The thing's so hard, you'll probably not see a mark before then.

I use a KMC X8 chain and a Surly stainless steel chainring with a standard Rohloff 16t sprocket inside my Chainglider, and for practical purposes it is silent. My test is to ride on the white or yellow line on a smooth tar macadam road; the paint removes my fat tyres from the equation. My bike is dead silent -- the electric motor is the loudest thing about it, surprisingly, and then the tyres on anything but dead smooth roads -- so I would hear instantly if my Chainglider grated.

There's a trick to fitting the Chainglider. If there's any kind of a contact noise, I move only one side, top or bottom, of the long tubes one notch in or out of the sprocket cover. The noise will lessen or increase. If it lessens, I try another notch, if it increases I try a notch the other way. If still no improvement, I try the other tube. It's probably a year since I last adjusted my Chainglider, at the time I fitted a Cospea crank and the Surly chainring.

What this adjustment does is a sort of magic. Clearly, the Chainglider must touch the chain somewhere, and I suspect it is at the chainring and sprocket, leaving the run of the chain between, where it would be noisiest because slack, to run just clear of the hard rubbery substance of the Chainglider. The adjustment seems to balance the two long tubes on the sprocket, so to speak, at the point of least interference. On my installation, it seems, magically, to be a point of no interference because there is no noise.

Robin advised me the chainglider needs a thinner ring, and gave an example:

http://www.sjscycles.co.uk/surly-110-pcd-5-arm-stainless-steel-chainring-38t-silver-prod20828/

I realize the Surly is not compatible with the T/A pattern, 49BCD crank you're running, but something to keep in mind. It would be helpful to know exactly how wide/thick the Surly 'ring is for comparision. No doubt Andre can enlighten us on both points, based on his own lengthy experience.

The 38T Surly stainless steel chainring is 2.6mm +- 0.01 thick by my measurement.

The Surly Robin recommends and that I use is a 110BCD fitment. I don't have enough mileage on mine to be able to tell anything about it, except that its square cut nature doesn't create additional noise. (It's intended for fixies and "single speed" bikes.)

Surly doesn't make a 52mm BCD fitting stainless chainring, so unfortunately you can't use a TA Cycletouriste with the attractive stainless chainring unless you make an adapter. Surly does however make 130mm chainrings, for which an adapter used to be available.

Andre Jute
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: martinf on July 30, 2012, 06:56:53 AM
The noise, and especially the grating, tells us there is something amiss in your installation. I'd check the inside of the Chainglider every 25 miles to see if the teeth or the chain sides are marking the plastic. The thing's so hard, you'll probably not see a mark before then.

There's a trick to fitting the Chainglider. If there's any kind of a contact noise, I move only one side, top or bottom, of the long tubes one notch in or out of the sprocket cover. The noise will lessen or increase. If it lessens, I try another notch, if it increases I try a notch the other way. I still no improvement, I try the other tube.

The 38T Surly stainless steel chainring is 2.6mm +- 0.01 thick by my measurement.

The Surly Robin recommends and that I use is a 110BCD fitment. I don't have enough mileage on mine to be able to tell anything about it, except that its square cut nature doesn't create additional noise. (It's intended for fixies and "single speed" bikes.)

Surly doesn't make a 52mm BCD fitting stainless chainring, so unfortunately you can't use a TA Cycletouriste.

I tried adjusting the notches (very quick to do), and think I have reached the best compromise for the transmission I have. I think the swishing is due to the TA ring being slightly wider than the max. specified by Hebie. For Rohloff use that means the Surly stainless steel ring at 2.6 mm would be a good option.

The grating is not very obtrusive. I can only really hear it when going slowly up fairly steep hills (masked by wind/tyre noise at normal speeds) and reckon it might be the slack lower run of the chain or maybe the ends of the chain pins, these stick out a bit on the old Sedis 1/8" chain I have on the bike, which I measured to be just inside 9 mm. Again, things would would probably improve  for Rohloff use with the eccentric bottom bracket to adjust chain tension and a narrower modern 3/32" chain. Chain tension adjustment on my 5-speed is a bit hit and miss.

So not a perfect fit for the equipment I have on my old 5-speed, but still usable. I now intend trying it out to see if:

1 - there are any performance reductions. For this I timed myself for four 25 km rides over a moderately hilly local route before fitting the chainglider, so I will do the same route 4 times with the chainglider to see if it makes any difference to average speed, bearing in mind that my current installation is not ideal.

2 - any other drawbacks, apart from the weight (not very significant) and the slight extra time needed to remove the rear wheel. As the 5-speed is my utility bike, it should get a fair amount of use before I order my Thorn.

3 - whether it works or not to reduce chain maintenance/increase transmission life. My test for this will be to go and ride a local cycle-track through the sand dunes for about 40 kms, then open the chainglider when I get back home. If its still reasonably clean inside I will consider the case proven.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on July 30, 2012, 01:11:46 PM
That sounds like a scientific plan, Martin.

(I can't resist: http://coolmainpress.com/ajwriting/archives/2490 )

For the record, a couple of notes. A Rohloff installation on a new hardtail that requires a chain tensioner to work is simply incompetent (1); it also defeats several purposes of fitting the expensive gearbox, among them low maintenance and long chain life. Also, a Rohloff chain is supposed to be quite slack; a tight chain will wear faster than necessary.

Andre Jute

(1) Of course, a Rohloff installation on a repurposed (old) frame with vertical dropouts simply has to use the chain tensioner unless you can find an eccentric bottom bracket small enough to fit in a normal bottom bracket shell.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: il padrone on July 30, 2012, 02:01:51 PM
I've just recently converted my wife's bike to Rohloff. It is a very reliable '93 Giant Sedona cromoly MTB, ideal for rough stuff touring and still in excellent condition. But it has vertical drop-outs so I have had to get the Rohloff with a chain tensioner (and torsion arm). So far this is all working quite well. I don't see how the maintenance of the hub will be compromised by this, and the wear on the chain should not be noticeably more than for any other chain. The heaviest wear factor for the chain is going to be the pressure put on the pedals, together with the amount of dirt and grit that gets onto the chain.

Time will tell I guess, but I'm not going to lose sleep over it.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: martinf on July 30, 2012, 04:42:21 PM
For the record, a couple of notes. A Rohloff installation on a new hardtail that requires a chain tensioner to work is simply incompetent (1); it also defeats several purposes of fitting the expensive gearbox, among them low maintenance and long chain life. Also, a Rohloff chain is supposed to be quite slack; a tight chain will wear faster than necessary.

Andre Jute

(1) Of course, a Rohloff installation on a repurposed (old) frame with vertical dropouts simply has to use the chain tensioner unless you can find an eccentric bottom bracket small enough to fit in a normal bottom bracket shell.

I had to use a tensioner on my testbed for different handlebar positions. This is the old mountain bike I took on my October 2011 tour to Spain and back. In addition to changing the handlebars I took off the deraillur parts and rear U-brake, keeping the largest 44T ring, which I moved to the middle position, and fitted a Nexus Premium 8-speed wheel.

I chose a Surly Singleator, pushing gently upwards to keep the chain on over bumps, but still leaving a bit of slack. I can always increase the tension if the chain comes off. The Singleator seems to add very little drag. But obviously not possible to try out the chainglider on that bike.

I timed five 50 km "before and after" rides around the same circuit in each configuration, flat bars/Nexus was about 3% slower than drop bars/deraillers.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on July 30, 2012, 05:03:26 PM
I timed five 50 km "before and after" rides around the same circuit in each configuration, flat bars/Nexus was about 3% slower than drop bars/deraillers.

This is very impressive indeed. I would say at a guess, open to correction of course, that the wider range of the Rohloff means that its efficiency loss might be about 1% that of derailleurs or even "lost in the margin of error". Of course, your impressive numbers depend crucially on using the gearbox well, which isn't the case for all Shimano Nexus riders... I've found that the Rohloff, for one reason and another, encourages a more sporting style of riding, working the box more often, less of a temptation to hang on to high gears.

Just as a matter of interest, I found that when I went to a fully automatic Nexus box ( http://coolmainpress.com/BICYCLINGsmover.html  ) from a manual Nexus box, I went perceptibly faster over the same old familiar daily ride because I wasn't hanging on to unsuitable gears. That Shimano Cyber Nexus setup was a real eye-opener. It left any derailleur system I ever rode for dead.

Andre Jute
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: triaesthete on July 30, 2012, 08:47:10 PM
Hi Martin
500km of testing is thorough. Chapeaux!

Does the singleator feel like a quality item. On One do something similar called a Doofer http://www.on-one.co.uk/i/q/FSOOSSD/on_one_doofer_singlespeed_chain_tensioner

General question: has anyone converted a Thorn Sherpa/Club tour/Audax to Rohloff  by:- A: using one of the above? B: welding extensions to the left rear drop out to modify it to take the oem torque arm?

If not does anyone think B is possible from materials and torque loading standpoints?

Interested
Ian
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: rualexander on July 30, 2012, 08:58:39 PM
I use my Sherpa with a Rohloff hub.
Started with chain tensioner but after a couple of months got rid of it once I found this (http://www.eehouse.org/fixin/formfmu.php) magic gear calculator which allows you to work out which chainring and sprocket combination will allow you to get a chain to fit without the tesioner. As Andre mentions above the Rohloff is happy with a slack chain so no problem.
For my Sherpa 610S a 38T chainring and 16T sprocket works fine.

I do use the long torque arm, but its no problem, only had the wheel off a couple of times in the past year anyway, it doesn't look great but that doesn't bother me.

There's a thread on my Sherpa here : http://www.thorncycles.co.uk/forums/index.php?topic=3235.0
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: martinf on July 30, 2012, 09:06:16 PM
This is very impressive indeed. I would say at a guess, open to correction of course, that the wider range of the Rohloff means that its efficiency loss might be about 1% that of derailleurs or even "lost in the margin of error". Of course, your impressive numbers depend crucially on using the gearbox well, which isn't the case for all Shimano Nexus riders... I've found that the Rohloff, for one reason and another, encourages a more sporting style of riding, working the box more often, less of a temptation to hang on to high gears.
Andre Jute

For me, with the rather subjective method of timing 2 sets of 5 rides, 3% is already a fairly negligible difference.

Unfortunately, it isn't a straight hub/derailler comparison because I changed the bars at the same time. I would expect flat bars to be slightly slower, due to the absence of brake levers I spend less time on the bar ends than I spend on the hoods with drop bars.

I would imagine that a Rohloff should do slightly better than a Nexus 8 Premium because:

1 - the gear steps of the Rohloff are closer, so slight gain from being in a more optimal ratio.
2 - the Rohloff runs in oil, the Nexus in grease (unless and until I find a low-hassle way of using it with oil).

Another factor is that my Nexus is nearly new and still on the original grease.

I've found that hub gears generally work better after riding for 1,000 kms or so, cleaning out the original grease/oil and relubricating.
  
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: martinf on July 30, 2012, 09:14:51 PM
Does the singleator feel like a quality item. On One do something similar called a Doofer http://www.on-one.co.uk/i/q/FSOOSSD/on_one_doofer_singlespeed_chain_tensioner

The singleator seems good quality, but I haven't used it for long. It came with two different springs, factory fitted for pushing down, and an another one for pushing up. I preferred to try the latter as it gives more chain wrap on the rear sprocket. It will cope with a max. sprocket of 24T, which I have.

From the photo, the singleator has one advantage over the Doofer - the spring is enclosed. Don't know how you adjust the tension on the Doofer, but the singleator is dead easy - loosen the mounting bolt with an Allen key, adjust the flats on the tension adjuster with a cone spanner, tighten the mounting bolt again.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: martinf on August 02, 2012, 08:19:06 AM
Got the answer for the first of my 3 questions about chainglider use.

1 - Are there are any performance reductions?

As far as I'm concerned, no.

Four 25 km rides over a moderately hilly, mainly rural, local route before fitting the chainglider, average speed 24.00 kph, another four 25 km rides over the same route with the chainglider 23,99 kph.

Slowest of the 8 runs 23.39, fastest 24.42 kph.

Total climbing for the 24 km circuit 210 metres, obviously the same amount of downhill.

The chainglider must make a tiny difference due to the extra 300 grams or so, but any friction generated by the thing riding over the moving chain seems to be fairly negligible, even with my imperfect setup.

I think the faint "swishing" noise, which I believe is the slightly too thick chainwheel rubbing in the front bit of the chainglider, has got quieter, but it might just be that I've got used to it.

Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on August 02, 2012, 02:00:36 PM
Got the answer for the first of my 3 questions about chainglider use.

1 - Are there are any performance reductions?

As far as I'm concerned, no.

Four 25 km rides over a moderately hilly, mainly rural, local route before fitting the chainglider, average speed 24.00 kph, another four 25 km rides over the same route with the chainglider 23,99 kph.

Slowest of the 8 runs 23.39, fastest 24.42 kph.

Total climbing for the 24 km circuit 210 metres, obviously the same amount of downhill.

The chainglider must make a tiny difference due to the extra 300 grams or so, but any friction generated by the thing riding over the moving chain seems to be fairly negligible, even with my imperfect setup.

I think the faint "swishing" noise, which I believe is the slightly too thick chainwheel rubbing in the front bit of the chainglider, has got quieter, but it might just be that I've got used to it.

That's a very fair report, Martin. Statistically, your rides are so well within the margin of error that we would have to say there is no performance degradation. I notice the "roadie caveat" about the influence of 300 grams, and grin, but in a 100kg or thereabouts all-up package the difference would be swamped in what you had for breakfast, and the time differential accounted for by an imperceptible change in wind speed or direction.

***

It will be interesting to see at which point interior wear from a chainring/chain outwith the recommended parameters becomes visible, and whether it continues  to wear, or settles when the Chainglider is worn just enough to give the unsuitable components operating space. Possibly that could be the point where it becomes totally silent. The Germans are notorious for overbuilding their components (not just bicycle gear) and then underspecifying it for public consumption: there's always a large margin built-in.

So I think it likely that in time we will discover that:

1. For marginally out of spec chainrings and chains no damage inside the Chainglider will ever be visible.

2. For any operable (but more than marginally larger than recommended) width of chain the internal marking of the Chainglider will stop when an accommodation is reached. Otherwise we would long since have heard of Chaingliders worn through in a few thousand kilometres, and we haven't.

3. A chain that is really too wide will be sticky inside the Chainglider and the drag will cause it to be removed. Speculation, of course, until some rich poster sacrifices a really thick chainring and Chainglider in the interests of bicycling science (could be a knighthood in it though...).

***

Congratulations on a thorough test, Martin.

I especially liked your test course, as one of my favourite rides is 22km with, you guessed it, 210m of climbing.

Andre Jute
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: martinf on August 03, 2012, 05:12:46 PM
Got the answer for the third of my 3 questions about chainglider use.

3 - Does it work or not to reduce chain maintenance/increase transmission life?

I did my test ride in the dunes today, 67 kms in all including the ride there and back, plus the sandy tracks, wet today because there were heavy showers. In a few places the sand was too soft to ride on, so I pushed, in these areas the wheels sank in about 5 cms.

After a few hundred metres in wet sand the chain would normally be grating, so I reckon the chainglider protects the chain quite well. In the photo of the chainglider you can see some of the sand that would otherwise have gone on the chain, but the rain has washed most of it off.

When I got back home I opened the chainglider. There was a small amount of water inside but I didn't find any sand. I did find some greyish paste near the chainring. After I cleaned that off and put the chainglider back together it seemed to rub even less than it did before.

So I'm satisfied that the chainglider is going to save me a significant amount of chain cleaning time and very probably increase chain/sprocket/chainring life.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on August 03, 2012, 05:15:02 PM
Martin!

I salute your efforts and testing methodology, and thank you for being kind enough to share the results with all of us.

Really well done!

(Loving the photos and bike, too)

All the best,

Dan.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: rualexander on August 03, 2012, 07:30:22 PM
On the subject of the Chainglider, how much dismantling is necessary to take the rear wheel out in the event of punctures, does the whole Chainglider have to come off or just the rear section?
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: il padrone on August 04, 2012, 12:12:57 AM
Martin, off the topic a bit, but what are the covers on your front wheel spokes?
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on August 04, 2012, 01:25:53 AM
Quote
...what are the covers on your front wheel spokes?
Hi Pete,

I can't answer for Martin, but they look a lot like something I've been looking at:
http://www.rei.com/product/808967/lightweights-for-wheels-power-reflectors
Company home page here: http://www.lightweights.org/store/product.php?productid=1
"Lightweights for Wheels Power Reflectors", little tapes of stick-on 3M Scotchlite that roll onto the spokes and make the wheels reflective. Same basic idea as the Reflex tape on Schwalbe tires, but for the spokes.

Best,

Dan. ("best guess")
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: martinf on August 04, 2012, 07:33:45 AM
Martin, off the topic a bit, but what are the covers on your front wheel spokes?

http://www.acelo-shop.com/16099832.html


SekuClip spoke reflectors made by 3M. Got my first packet direct from Germany, but now my local bike shop stocks them. I think they are more effective than reflective bands on tyres and the traditional type of flat reflector. Being cylindrical in shape, they are visible from more angles. Also fairly light and don't unbalance the wheel.

Didn't put them on the back wheel as oil from the chain and my Sturmey hub quickly dulls out reflectors. I might try now I have the chainglider. On the front wheel they still pick up grey mess from the rim brakes, but generally stay cleaner than reflective bands on tyres.

For butted spokes on another bike I had to use a bit of insulating tape round each spoke to increase the diameter so that the SekuClips would hold.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: martinf on August 04, 2012, 07:43:39 AM
On the subject of the Chainglider, how much dismantling is necessary to take the rear wheel out in the event of punctures, does the whole Chainglider have to come off or just the rear section?

Theoretically just the rear section, which is in two parts. I had it apart yesterday to check the inside, the whole thing comes apart very quickly indeed, it takes a little longer to put back together and it is a good idea to memorise the adjustment before dismantling - i.e. how many ribs are visible top and bottom at the join between front and rear parts.

I don't consider it an issue, for one thing it doesn't add much time, and anyway punctures are very rare with the Marathon tyres I have on that bike and the Supremes/Duremes I intend to run on my future Nomad. The chainglider might even make things easier, as I suspect there will be less oily mess around the rear wheel.

Incidentally, I often don't bother removing the wheel to fix rear punctures on hub gear bikes - if the weather is dry and not too cold I get the tyre off the left side of the rim and pull enough of the tube out to patch it in situ rather than replacing the tube and patching later.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on August 04, 2012, 04:29:07 PM
it is a good idea to memorise the adjustment before dismantling - i.e. how many ribs are visible top and bottom at the join between front and rear parts.

Since I ride on banded tires, I've only had the rear wheel out perhaps once a year, for the bike's spring clean, and memorizing the adjustment didn't occur to me. The usual adjustment, if you get the initial fit wrong by feel of how tight the rear part of the Chainglider slots in against the sprocket teeth, is usually just one click outward, either top or bottom, so a 50/50 chance of getting it right first time. So I fit the Chainglider, wheel the bike a pace backwards and forwards, and if there is the slightest noise, I make an adjustment, wheel it again, and make the other adjustment if necessary. That's it. (I don't ride the bike for this test because the roads here are rough enough for tyre noise to drown out the noise of a maladjusted Chainglider: even maladjusted, the thing makes very little noise indeed. But the patio in front of the stables, and the sidewalk in front of my town house, where I tend drop the wheel, are both smooth enough for this test.)

But for those of you who still ride on unbanded or inadequately banded or vulnerable soft sidewall tyres, Martin's idea of remembering the adjustment by the number of lockribs showing is excellent. Also works by feel in pitch dark for the tourers.

Andre Jute
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: il padrone on August 05, 2012, 11:01:17 AM
My Chainglider arrived on Friday. I fitted it yesterday and took it on a 69km ride through the hills today. It only lasted 10kms  :o

I made a discovery - the Chainglider does not like running with a Thorn reversible chainring. I thought it might be OK, gave it a go, but by the time I was climbing the first steep hill, and everyone was leaving me behind it was obvious that the swooshing noise really was increasing my pedaling drag  :(. The black chainring has a nice silver rim about it now. I took the Chainglider off and rode the rest of the ride much more easily.

I shall have to buy myself a narrower chainring (maybe a stainless one rather than alloy) and swap it on. Thing is this would make the most sense when the chain has worn out and I can fit a new chain with the new chainring. This chain is on the way out - done about 3500km. But it is one of three I am rotating, so between the three it could be another 2-3 years or more before I really need the new chain  :-X

Anyway, be aware, Thorn reversible chainrings do not work with the Chainglider, they are just too thick.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on August 05, 2012, 05:43:44 PM
Anyway, be aware, Thorn reversible chainrings do not work with the Chainglider, they are just too thick.

Now we're establishing parameters! Anyone know how thick the Thorn reversible chainring is?

Hebie's spec for the Chainglider: max chainring thickness, 3mm; max chain width, 9mm.

The Surly stainless chainring, also reversible, is 2.6mm by my measurement. It works fine with the Chainglider. SJS stocks it 5-arm  110mm BCD suitable in 38/40/42 tooth:
http://www.sjscycles.co.uk/surly-110-pcd-5-arm-stainless-steel-chainring-38t-silver-prod20828/
http://www.sjscycles.co.uk/surly-110-pcd-5-arm-stainless-steel-chainring-40t-silver-prod27315/
http://www.sjscycles.co.uk/surly-110-pcd-5-arm-stainless-steel-chainring-42t-silver-prod19787/

Andre Jute

PS Sorry about your scuffed chainring, Pete. It never occurred to me that the Chainglider would mark it until I saw Dan's post below. I expected the Chainglider to be marked by the metal, instead.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on August 05, 2012, 05:53:13 PM
When I inquired about the Chainglder, Robin advised using the Surly stainless chainring with it; others were simply too thick to work well.

My thinking was if the Chainglider cleared a chain...it must surely clear a chainring, which is narrower. The cover must somehow snuggle in around the chain for a close fit at the 'ring?

Never thought it might result in a scuffed finish on the 'ring...I just thought it might be a little noisy, and that would soon clear with use.

'Wish I had thought to warn Pete, but he had already placed his order and I didn't think to check what chainring he was using, else I surely would have sent him a note before he tried it.  :'( Sorry, Pete.

Best,

Dan.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: martinf on August 06, 2012, 01:38:56 PM
It never occurred to me that the Chainglider would mark it until I saw Dan's post below. I expected the Chainglider to be marked by the metal, instead.

I think the small amount of grey paste I cleaned off the area of the chainglider near the chainring the other day is a mix of aluminium off the chainring and plastic off the chainglider - rather like the muck formed by rim brakes.

Didn't notice any wear marks on my chainring, but it was already rather weathered before I fitted the chainglider and I didn't examine it particularly closely.

Unlike Pete, I haven't noticed any slowing effect, maybe its the black anodising or maybe the Thorn ring is just thicker than my TA ring.

It would seem that chainring choice is fairly critical for a chainglider to work well.

To get back on topic, instead of my original 50/21 choice I will now go for a 38T chainglider-compatible Surly steel ring and 16T sprocket on my future Thorn Nomad.

I maintain several other hub-gear bikes. The chainglider isn't compatible with the family Bromptons, nor with two of the large-wheel bikes. There is a tensioner on my 8-speed and there isn't a chainglider version for the 32T chainring/22T sprocket on my wife's 5-speed.

But the two visitor bikes at our island flat have 38T/22T so should be compatible. These are already as "low maintenance" as I could get them to be, with 3-speed gears, drum brakes and Marathon Plus tyres, so chaingliders would be a logical addition, with the added benefit of protecting visitor's clothing from chain oil (not really a factor for my own cycling use).

Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: E-wan on August 06, 2012, 01:54:42 PM
I run 50x17 on my nomad with 165mm cranks

find it fine most of the time, can clime most things on the road I would want to with a moderate load peadiling up 16% gradient or so.

if towing my child trailer the its fine on steep hills unless I try and carry more than 1 pannier as well, then I would probably want something lower.

If I go of road this gearing is to high.

I also have a 40T ring but have never swapped to it yet.  I am running a SRAM chain and would intend to use  a couple of power links to make it easier to swap for a lower gear if necessary if I wanted to.


I often find myself in 13-14 with this gear combination on the road and if going downhill could make use of 2-3 higher gears.

Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: martinf on August 08, 2012, 01:05:43 PM
Found this link to a short Chainglider test:

http://www.bicycles.net.au/2012/07/squeak-free-clean-bike-chain-hebie-chainglider/

Also read that you shouldn't use a master link with the Chainglider - my 1/8" chain on the test bike has one of the old style 3-piece master links, so probably exceeds the 9 mm maximum at this point.

I don't suppose a modern 3/32" quick link (SRAM Powerlink or similar) would pose problems, but I gave up using those after having some come apart when riding.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: berchman on November 25, 2012, 12:26:23 AM
I have just resumed cycling after a thirty year layoff. I sold my two DF bikes and bought a recumbent trike (Catrike 700) with a Rohloff hub. I have a 36/16 with a 700c x35 tire. I find the gear information on the Sheldon Brown site somewhat confusing, so would appreciate it if someone were to tell me what my gear range is in inches. I calculated 19-99, but I don't know if that's correct. Being an old guy and a weak rider, I find I need gear 1 on some of the hills around here. I have not yet determined the percent grade they represent, but I have acquired a GPS and plan to do so. They are definitely not the steepest hills in my area. On the flat I usually use 8. I have been thinking that to tackle a real killer hill I would definitely need a considerably lower gear. Does anyone know what a Schlumpf drive would give me with the 36/16 combination?
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on November 25, 2012, 01:24:43 AM
Hi Berchman!

Welcome to the Forum! Though a diamond frame hasn't worked out well for you, hopefully the recumbent/Rohloff combo will do the trick. "Old guy"?!? How 'bout "experienced"?  ;) So long as you're back on the bike, the type that allows it isn't so important -- it is the doing that counts!
Quote
I find the gear information on the Sheldon Brown site somewhat confusing, so would appreciate it if someone were to tell me what my gear range is in inches.
Here is an alternative that offers a graphic representation; I really like this Rohloff gear calculator:
http://www.gear-calculator.com/#
Once at the link, go to the section on the left labeled "Gearing" and pull down the option for "Rohloff Speedhub". Everything else is a matter of just selecting your chainring/cog combo. Hint: the 'rings and cogs can be dragged across the grid to quickly see the results of a change. A very nice little tool for comparing alternative drive schemes, including Rohloff/Rohloff or Rohloff/Derailleur.

An alternative gear calculator that can be made to work for a Rohloff/Schlumpf combo with a little finagling is available here:
http://rbr.info/support/guides/151-gear-inch-calculator.html To make it "go", first use the calculator I referenced at the earlier link. That way, you can see what your Rohloff gearing is and back-engineer it to see what 'rings and cogs would be required to match it in a der setup. Note the "naughty" combos and lay them aside. Then, take that 'ring/cogset combo and enter it in the Schlumpf calculator immediately above. This will do the pencil-work for you. For example, if your Rohloff setup is the equivalent of a 22/32/44 chainset with an 11-12-14-16-18-21-24-28-32 cassette, enter that, then select the "Internal Hub - Schlumpf Mountain Drive Bottom Bracket" option and off you go. You'll get two charts, each showing a full range of 27-speeds available for 1.0 (same as stock) and 0.4 (reduction) depending on which "gear" you select in the Schlumpf.

For quick reference, using a nominal 27" wheel for the calculations, the 1.0, 22x32 combo yields a low gear of 18.6 gear-inches. With the 0.4 Schlumpf reduction Mountain Drive engages, that same 22x32 combo yields a low gear of 7.4 gear-inches, a gear so low balance becomes a real problem, though you could easily pull stumps with it. With a trike, balance wouldn't be a problem!  ;D Rohloff longevity will definitely be the limiting factor. These low gear-inch numbers point out the care needed to avoid over-torquing the Rohloff hub, and also the need to carefully figure your low gearing to best take advantage of that the Schlumpf low can really offer. Obviously, it won't be practically useful to have a lot of gears down in the single-digits in terms of gear-inches.

Back in the days when I was a do-it-yourself derailleur gearhead, I found I could still comfortably pedal a 12 gear-inch low gear at about 2.5mph and my usual 100RPM+ cadence, but that was about as low as I could practically go; my Dad never did adapt to it. A 15 gear-inch low was both comfortable and practical and Dad did just manage that (the difference between us was our cadence, with mine being very fast and smooth; at slower cadences, balance becomes a real problem in such low gears). Slope is a factor as well. The steeper the slope, the lower the gear one can balance, at least in my experience. I did just manage a 10 gear-inch low on a 24% grade, but forward progress was truly slower than walking and a person gets as worn out from the cadence/effort as if they were pushing a much higher (i.e. 16.5-gear-inch) gear.

Quote
I have been thinking that to tackle a real killer hill I would definitely need a considerably lower gear. Does anyone know what a Schlumpf drive would give me with the 36/16 combination?
You will likely exceed the torque capacity of your Rohloff hub if you pair it with a Schlumpf *reduction* ("Mountain") drive. Rohloff have a lot to say on the matter here: http://www.rohloff.de/en/service/faq/faq_detail/archive/2005/11/july/article/Schlumpf_Speed_Drive_High_Speed_Drive_Mountain_D/index.html
Quote
When fitting a Schlumpf transmission, please bear in mind that it is still important not to undercut the smallest permitted sprocket ratios (see 'sprocket ratios').

The Schlumpf Mountain Drive is not permitted for use in conjunction with the Rohloff SPEEDHUB 500/14.

The Schlumpf High Speed Drive (1:2.5) is not permitted for use with the Rohloff SPEEDHUB 500/14 due to its standard 27 tooth integreated chainring. A number of alternative chainring sizes are however available from schlumpf so as to not undercut our smallest permitted sprocket ratios.
The Schlumpf Mountain (reduction) drive offers a 2.5 reduction ratio over whatever you're already running. The people who can best advise you as to the risk are CycleMonkey, who sell both. See: http://www.cyclemonkey.com/schlumpf-innovations.shtml Schlumpf have something to say about this combination as well, in their FAQ (Section 3.2) here: http://www.schlumpf.ch/hp/schlumpf/faq.getriebe.engl.htm#C

Some specific help for your question from people who have been there is available here:
http://www.bentrideronline.com/messageboard/showthread.php?t=38628
http://www.ihpva.org/projects/tstrike/building/rohloff.htm

As for quickly judging the grade of your hills, I can heartily recommend the SkyMounti inclinometer, which calculates rise-to-run as a direct-reading percentage to match road grades. Just match the leading or trailing edge of the bubble with the grid on the scale. For more on this fun and entertaining little gadget, see this post: http://www.thorncycles.co.uk/forums/index.php?topic=3896.msg20102#msg20102

I hope this helps.

Best,

Dan.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: berchman on November 25, 2012, 02:19:56 AM
Thanks Danneaux, very helpful.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on November 25, 2012, 04:22:41 AM
The actual range of a Rohloff Speedhub on a 622x35 wheel/tyre combo with a 36x16 tooth gear combo would be 17.1 gear inches up to  89 gear inches. I don't know if you're a spinner or a masher but at 60rpm that's from 5.6kph to 29.5kph. On a trike you won't have balance problems, and you say you aren't a strong pedalist, so I wonder if yours isn't a really good case for ignoring Herr Rohloff's ultra-conservative rating on his gearbox and going even higher that the 2.250 ratio you have chosen (that's a lower number than 36/16).

I don't know about the Schlumpf. I looked into it but it would duplicate so many gears, one's head spins dizzily, and you gain only a gear or two, at most three, which you can anyway cover by coasting down the hills rather than pedalling madly, trying for undignified speed, sacrifing a gear or two at the top to add them on at the bottom. (I'd kill myself if I tried to keep up nearly 30kph on the flat!) The Schlumpf is actually good for something entirely different (for giving young, fit guys more top end breathing room without losing all their bottom end), but for adding low gears to the Rohloff it is expensive overkill. Just my opinion. If you are really keen on the Schlumpf, I can work the numbers again to allow for the Schlumpf.

Hope this helps.

Andre Jute
Are you the Keymaster? -- Ghostbusters, the movie
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: berchman on November 25, 2012, 01:51:57 PM
I am neither a spinner nor a masher. Until I get a cadence sensor installed, I'm guessing that I comfortably pedal about 70 RPM. I have no interest in pedaling downhill; the trike goes fast enough coasting downhill to put some fear into me. I think you have just saved me the expense of the Schlumpf; I rarely find myself pedaling in gear 14.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on November 25, 2012, 02:53:26 PM
What a couple of us on this conference have done to extend the range, in both the senses of the steepness of hills we can stilll attack and the distance we can still ride in any period -- in short to keep us cycling, is to fit an electric motor to fill in the gaps. This seamless solution has met with considerable acclaim from everyone who tried it. I'm not necessarily suggesting it to you if your Rohloff's range, as now revealed in the gear inch spread, will get you by on your roads, but it is a superbly practical, workable solution to keep you cycling through health problems, encroaching age, and so on.

My installation is fully described at http://coolmainpress.com/BICYCLING.html (http://coolmainpress.com/BICYCLING.html) and there is considerable discussion on this board which you can find with the search function.

Andre Jute
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Tigerbiten on December 08, 2012, 01:45:54 PM
I've a Rohloff and Schlumpf HSD on my recumbent ICE trike.
The gear range with this combo is fantastic as it gives you another 7 gears above the normal range.
I run in touring mode 30/16 on 50-406 tyres which gives me the range 10"-130" in 21 steps, ~1.7 mph min to ~40 mph max.
This is well below Rohloff's minimum spec of 14", so if anything breaks it will be my own fault.

I think get away with it three reasons.
1:- I'm on a recumbent, so I cannot standup and honk up hills. So less maximum force through the pedals.
2:- Small wheel, so the Rohloff is spinning faster than if it was in a 700c wheel, so less strain on it.
3:- It's a trike, so no real minimum speed hill climbing. My normal minimum speed is only around 1.7 mph so I'm putting half the force through the hub as compared to having to keep a speed of around 3.5 mph just to balance. Only +20% hills get hard work.
So far I've had it around one year and covered around 6k miles on it.
Tend not to use the overdrive with the bottom half of the Rohloff as it duplicates the top half of the Rohloff in normal drive mode. You can fell the extra drag from all the hubs spinnings.
The main downside is I spinout in B14, the gear before I switch into overdrive, at only 15-16 mph. This really is one gear to low.
I'm thinks of fitting the 21t rear sprocket on the Rohloff and then getting the spider for the Schlumpf HSD so I can fit a 48-36 tooth double.
This would let me keep the silly low gears while also upping the top end a bit.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on December 08, 2012, 11:15:48 PM
Fascinating, Tigerbitten; I reread that several times and hauled out my gearing spreadsheet, which has a Schlumpf on it from when I considered it for myself. Thanks for that. More ways than one to skin a cat, for sure!

Andre Jute
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Slowlegs on December 17, 2012, 11:17:51 AM
Just released on the Rohloff website..
They have reduced the lowest permissible ratio from 2.35 to 2.1 (for riders who weigh under 100kg)

So for a 17 tooth rear sprocket thats a reduction from 40 at the chainring to 36 (my calculation). Great news for large loads, steep hills, high altitudes and for when you've run out of jelly babies.

Link:
http://www.rohloff.de/en/news/news_rss/news_in_detail/archive/2012/11/december/article/SPEEDHUB_UEbersetzungsfaktor_von_mind_235_auf_ak/index.html

Regards
SL
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andybg on December 17, 2012, 11:50:40 AM
Definetly a move in the right direction and good news for us spinners

Andy
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on December 17, 2012, 05:13:17 PM

I've long said that Herr Rohloff revels in a massive built-in margin of safety on his hubs. (And Andy Blance and others said it before me.) Now we know how much the superfluous margin was: at least 12%. "At least" because it is difficult to believe that the habits of a cautious German engineer have suddenly changed all the way. If that happened, Frank Sinatra would crawl out of the grave to come sing the theme tune...

That's a very interesting report, especially the admission that the maximum load on the Rohloff gearbox was set by reference to derailleurs. Let's see: a sturdy set of solid gears, totally enclosed, running in an oil bath, not permitted to be stressed more than a derailleur with thin lightweight bits, being abraded out in the open with one of the most efficient grinding pastes (ground rock and light oil mixture) known to man. Yup, that sounds fair...

Twenty years later, the goalposts have shifted for derailleurs, and the Rohloff goalposts are moved — to match derailleurs exactly!

I'll take bets that there will be no perceptible increase in Rohloff hubs being returned for service, or reported as broken or damaged because of the new permitted cog ratio.

In fact, I'll bet money that we'll eventually discover that the real capability of a perfectly reliable Rohloff hub is a cog ratio in the order of 1.7 or better, something totally undreamt of in derailleurs. Those are two fundamentally different types of gearboxes, so the claim that this is the last permission shift is as "reasonable" (heh-heh) as the way the ratio was set in the first instance.

Call me a cynic if you like...

Andre Jute
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: martinf on December 17, 2012, 06:29:35 PM
In fact, I'll bet money that we'll eventually discover that the real capability of a perfectly reliable Rohloff hub is a cog ratio in the order of 1.7 or better.

You're probably right.

And their 2.1 ratio is for 100 Kg riders, so those of us who weigh significantly less than this should have an additional margin of safety.

The Rohloff announce comes just a few weeks too late for me - I would have specified 38x17 (lowest ratio that fits a Chainglider) instead of the 38x16 I chose in order to remain within the approved range.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: berchman on December 17, 2012, 06:39:20 PM
I have a 36/16 and will soon be substituting a 32/16 and, if necessary, a 32/17. At my age (75) and level of fitness I have no fear of damaging the Rohloff with excessive torque.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on December 17, 2012, 06:54:23 PM
Quote
The Rohloff announce comes just a few weeks too late for me - I would have specified 38x17 (lowest ratio that fits a Chainglider) instead of the 38x16 I chose in order to remain within the approved range.
<nods> That's exactly the direction I'm heading, Martin, going from a 40x17 to a 38x17 just as soon as I can convince Surly to produce a 38T stainless 'ring in 104BCD for my HollowTech II crank. Currently, their 104BCD 'rings top out at 36T -- fine alone, but too small for a Chainglider at present. Now, if we could just talk Hebie into producing a 36T-compatible Chainglider....

As an aside, Andre, I think the spinners among us may have a bit more leeway in Rohloff's safety margin than the mashers will. Fast 'n' light keeps my knees happy, says Dan of the hummingbird cadence.

A very nice find well-shared, SL, many thanks and welcome to the Forum. You too, berchman. Nice to have you both aboard.

Best,

Dan. (...who is really looking forward to some stump-pulling low gears now they are "Rohloff-legal" and won't void the warranty)
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: martinf on December 17, 2012, 09:02:13 PM
<nods> That's exactly the direction I'm heading, Martin, going from a 40x17 to a 38x17 just as soon as I can convince Surly to produce a 38T stainless 'ring in 104BCD for my HollowTech II crank.

As André has pointed out in another thread, it might be a long time before I do the change. Hub gear sprockets generally last me at least 5,000 kms each side.

I am expecting the Rohloff one to last significantly longer, due to the Chainglider.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on December 17, 2012, 09:32:08 PM
We may also have to wait for the peripheral manufacturers. I spent half an hour today with my gearing spreadsheet, and decided I'm okay on 38x16, what with the motor filling in the really steep hills. 38x17 on my 29-er would be still one step away from the new permitted ratio but I don't think it would make much difference to me. 36x16 or even 36x17 would be different enough to consider, and may be necessary if I want to remove the motor, but then the absence of a suitable Chainglider size would weigh seriously against those ratios. But eventually Hebie will catch on, and a year or two later catch up...

Martin, my Rohloff sprocket has done 6200km, all of it in a chain case, and there is little sign of wear on it. 10K on the first side is distinctly likely.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on December 18, 2012, 05:40:36 AM
Hi All!

Might be kinda nice -- assuming the cogs and/or 'rings had little use, as Martin's and mine do -- to advertise them for exchange/swap or at discount on the Bike Bits/Accessories For Sale board, here http://www.thorncycles.co.uk/forums/index.php?board=17.0

This would not work, of course, if the components has more advanced wear with the same chain, but might work well if they were largely unused or had an unused face/side. It would be a little less expensive than buying new for experimentation, and would provide a ready means to get the gearing one wants.

I may go for a 36x17 in place of my 40x17. Basically, I would exchange an 89 gear-inch high I'll rarely if ever use for a more practical 80". At the low end, I would gain a most welcome 15" to slot in below my present 17" which would become my new Gear 2. Not bad, swapping a too-high high for a more useful low.

My favorite cruising gears are 58" and 62" on my half-step derailleur bikes,  all at my usual 110RPM cadence (good for a cruising speed of 17-21mph/27-34kph in those gears; plenty for me). I have close to that at present with my 53"/61" Gears 10/11, but I find myself shifting more often to Gear 10 when loaded and it is a little low once I make the jump. The 36T chainring would give me 55"/62" Gears 11/12, which is a much nicer combination and placement for me. I also get a my favoed 42" in exchange for a nearly identical 41" for slogging into headwinds. For my riding, the 36T chainring gives me 14 gears I'll actually use, rather than 13 where my two favorite cruising gears aren't quite right and a low about 1 gear too high when fully loaded on 16%-24% grades. Looks good.

Best,

Dan.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on December 18, 2012, 09:11:53 AM
Done deal; I placed my order a few moments ago for a "fits up to 38T" Thorn 104BCD bash guard and snagged a 36T/104BCD Surly stainless 'ring on eBay. They may arrive after Christmas, but Santa (in the form of family members) had a hand in it.

We'll see how it goes, but I won't miss a high too high for my needs, and will be happy to have one gear lower when winching my way up antelope trails and goat tracks in the Pueblo Mountains, Wallowas, Ochocos and Calapooyas, carrying a full load including 15-odd liters of water and a week's-plus supply of food.

Best,

Dan.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on December 18, 2012, 02:01:35 PM
I may go for a 36x17 in place of my 40x17. Basically, I would exchange an 89 gear-inch high I'll rarely if ever use for a more practical 80". At the low end, I would gain a most welcome 15" to slot in below my present 17" which would become my new Gear 2. Not bad, swapping a too-high high for a more useful low.

Gee, is it only ten years since Andy Blance thought it was necessary to defend "low gears" like 40x17?

Andre Jute
Who can do enough math to have been on 38x17 from the beginning, except the dealer wouldn't fit anything not sanctioned by Rohloff
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on December 18, 2012, 05:58:46 PM
Quote
...except the dealer wouldn't fit anything not sanctioned by Rohloff
<nods> Yep, Andre; exactly why I went with the "approved" spec; I value the warranty, though there was ample evidence of sufficient safety margin. And, yes, as you observed, a margin still remains, but I won't exceed official recommendations 'cos of the value of that warranty to me. Not an inexpensive bit of kit, the Rohloff, and it is nice to have the backing for it. A margin also equates in my mind to a greater practical guarantee of reliability; my little boat is sunk if the thing fails on me in the places where I'll be taking it. 'Wouldn't mind having a bit of remaining margin for that kind of use.

All the best,

Dan.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Pavel on December 18, 2012, 07:41:48 PM
Mine is 41 teeth a 17 rear cog.  I have, for the riding I've done thus far, decided that the combo is a bit low for me.  I find that even though I am now very weak that the lowest gear is so low that at a good cadence I only go about 4 to 4.5 miles an hour uphill and at the same time I can push between 2 and three miles an hour.  I like to get off the bike and push much of the time, partly because it also seems to rejuvenate me as it is using different muscles.  Now I also don't care to go too fast even when I can.  There is something I like about puttering along and I rarely peddle downhill to go faster, except (seriously) only to keep up with my daughter who seems to find "the faster the better" exhilarating.  Me ... I like to go no faster than about 25 mph so I don't have to pay too much attention, to things other than the beauty around me. 

One of these days I hope to get up enough energy to write a good in-depth (sixty page? :D ) review of some of the gear. I sure do have strong opinions of much of it.  Some things worked marvelously, far beyond expectations and other things were surprising duds and extremely frustrating. (listening by chance mr Garmin?!)

The Thorn Nomad itself, overall, was beyond my ability with superlatives. Not often do product satisfy so much that it really, feels better to say nothing, rather than injure the truth with pale, pale, inadequate adjectives. Ditto of course for the heart of the machine, the Rohloff hub.
Fortunately :) I did find minor quibbles with the bike. I say "fortunately" because I think it absolves me of the worry that I've lost all my objectivity - I don't have to fully feel like a drunk soccer fan having a religious experience in the arena.

One chinks in the halo was the quality of the front chainring. It just simply was not up to the same level as the rest of the bike. Somewhere in Illinois at about the two thousandth mile of its life one of the teeth chipped and broke with the forward leading edge losing about half of the material.  It happened to be just at the point where the tooth takes up the chain at the top of the power point on my right foot and with any normal push caused a very loud popping sound with each revolution. Never mind Chinese water torture - this was worse! reversing the ring and rotating the bad tooth into a different spot gave me my sanity back for the rest of the trip and then when I got home I ordered a replacement, disappointedly, from Surly. The Surly front chainring is made of steel and I think that works far better with the Thorn emphasis of ruggedness. The switch gave me the chance to ponder what really I liked in the gear ratios and I went only a bit higher with a 43 ring, the second time around. It is only a subtle difference, probably akin to losing about half a step at the lowest end. It works well though and I think the 43/17 combo is the best set for me, as someone who walks up parts of many a hill. If I were cycling in Kansas with no hills but rather a constant wind - I suspect that I may then want perhaps a 40/17? It's hard to say though because at some point one simply goes too slowly to stay upright, right?
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on December 18, 2012, 07:59:27 PM
If I were cycling in Kansas with no hills but rather a constant wind - I suspect that I may then want perhaps a 40/17? It's hard to say though because at some point one simply goes too slowly to stay upright, right?

No balance worries on a tricycle! Maybe it's time for you to progress (?) to a Scootertrike. http://www.scooterbike.com/st-touring-e.html (http://www.scooterbike.com/st-touring-e.html)

Andre Jute
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: revelo on January 09, 2013, 04:46:50 AM
Mine is 41 teeth a 17 rear cog.  I have, for the riding I've done thus far, decided that the combo is a bit low for me.  I find that even though I am now very weak that the lowest gear is so low that at a good cadence I only go about 4 to 4.5 miles an hour uphill and at the same time I can push between 2 and three miles an hour.  I like to get off the bike and push much of the time, partly because it also seems to rejuvenate me as it is using different muscles.  Now I also don't care to go too fast even when I can.  There is something I like about puttering along and I rarely peddle downhill to go faster, except (seriously) only to keep up with my daughter who seems to find "the faster the better" exhilarating.  Me ... I like to go no faster than about 25 mph so I don't have to pay too much attention, to things other than the beauty around me. 

One of these days I hope to get up enough energy to write a good in-depth (sixty page? :D ) review of some of the gear. I sure do have strong opinions of much of it.  Some things worked marvelously, far beyond expectations and other things were surprising duds and extremely frustrating. (listening by chance mr Garmin?!)

The Thorn Nomad itself, overall, was beyond my ability with superlatives. Not often do product satisfy so much that it really, feels better to say nothing, rather than injure the truth with pale, pale, inadequate adjectives. Ditto of course for the heart of the machine, the Rohloff hub.
Fortunately :) I did find minor quibbles with the bike. I say "fortunately" because I think it absolves me of the worry that I've lost all my objectivity - I don't have to fully feel like a drunk soccer fan having a religious experience in the arena.

One chinks in the halo was the quality of the front chainring. It just simply was not up to the same level as the rest of the bike. Somewhere in Illinois at about the two thousandth mile of its life one of the teeth chipped and broke with the forward leading edge losing about half of the material.  It happened to be just at the point where the tooth takes up the chain at the top of the power point on my right foot and with any normal push caused a very loud popping sound with each revolution. Never mind Chinese water torture - this was worse! reversing the ring and rotating the bad tooth into a different spot gave me my sanity back for the rest of the trip and then when I got home I ordered a replacement, disappointedly, from Surly. The Surly front chainring is made of steel and I think that works far better with the Thorn emphasis of ruggedness. The switch gave me the chance to ponder what really I liked in the gear ratios and I went only a bit higher with a 43 ring, the second time around. It is only a subtle difference, probably akin to losing about half a step at the lowest end. It works well though and I think the 43/17 combo is the best set for me, as someone who walks up parts of many a hill. If I were cycling in Kansas with no hills but rather a constant wind - I suspect that I may then want perhaps a 40/17? It's hard to say though because at some point one simply goes too slowly to stay upright, right?

I originally picked a 42/17 ratio because that best matched my old MTB and I didn't know much about the subject at the time. Also, like you, I thought that it was simpler to get off and push when I slowed down below 4mph. And it is still much simpler to push on rugged dirt roads at low speeds. But I find that I can keep pedalling at under 3mph on a smooth road and pedalling is a LOT easier for long ascents than pushing a heavily loaded bike, and I find myself encountering these long ascents fairly frequently. For example, 12 miles and 3000 feet of ascent, or 5% grade overall with stretches of 10% grade and 4+ hours of steady pedalling--a LOT easier to pedal than push. I don't mind pushing, and I better not mind since I do plenty of it on rugged roads and in deep sand, but pushing for 4+ hours uphill is a bit much.

Also, if you really don't much care about high speeds (I don't care myself), then what is the point of ratios above 80 gear inches, which is what you are getting with 41/17? As Andy Blance points out, you can always coast downhill if you run out of gears on the top side, but someday you may change your mind about pushing versus pedalling, and there is no substitute for lower gear ratios if you want to pedal but gear 1 is too difficult.

Thus I've decided to switch from 42/17 to either 36/17 or 40/19. I noticed no one has discussed that 19T sprocket made by Thorn. It is currently out of stock, whereas the Rohloff sprockets are in stock. If I'm going to switch from 42/17 to something else, I don't want to first switch to 40/19 and then have to switch again to 36/17 if Thorn decides to stop making the 19T sprocket. It appears they've already given up making the 21T sprocket, which was their previous alternative to the smaller Rohloff sprockets, so who knows what to expect with the 19T in the future. Anyone else thought about this?
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on January 09, 2013, 05:05:19 AM
Quote
Anyone else thought about this?
Hi Frank!

I went from a 40x17 to a 36x17 just the other day. I detailed some of the reasons here:
http://www.thorncycles.co.uk/forums/index.php?topic=5573.0

I decided to go with the 17T cog rather than a 19 or 21 because it is more available, and directly so from Rohloff. It is my attempt to future-proof the bike to a degree, and help ensure easier parts availability down the road. For that same reason, I mounted my original Rohloff shifter on a T-bar rather than go with the Gilles Berthoud or Co-Motion 'bar-mounted shifter (both very nice options, but less likely to find ready repair parts or replacements for in future).

The 17T has the added benefit (for me) of fitting inside a Hebie Chainglider, an option I wish to use for at least part of my riding. Here in the cooler months' generally rainy and damp Willamette Valley -- between desert tours in the Great Basin -- it would be a nice way to reduce chain maintenance. I can always remove the Chainglider and replace my Thorn bash guard for touring in talc-fine playa.

All gearing choices are compromises to a degree, but -- for me, given my preferences -- this looks to be the best combo yet in balancing usability, wear, and -- yes -- comfort. The 17T cog allows me to keep the chainring and cog as physically large as possible (given my preferred low) to reduce wear and still get my preferred range. This is a bit of an experiment for me, but compared to the consumable costs of a derailleur drivetrain (three chainrings and a cassette plus chain), even a complete chainring and cog for the Rohloff are pretty modest investments so I can afford to play a little and see which combination works best over the long run.

So, 36x17 it will be for awhile. Looking forward to the lower gearing, close to what I have used and preferred on past derailleur bikes and proven suitable for my needs.

Best,

Dan.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: John Saxby on January 12, 2013, 10:05:01 PM
Dan, at 36 x 17, have you not ventured into The Dreaded Red Zone?  I can understand your reasons for doing so, with back-country camping and all, but how do you square your change to 36 x 17 with your earlier preoccupation about the Rohloff warranty? (I too bow to the recommendations of German engineers, but I also remember the remark [attributed to Gandhi] that "Consistency is the hobgoblin of small minds.")

This is all very useful, both the exchange of experience with ratios, and the Hebie Chainglider conversation.  Will factor both into my choices later this year -- no doubt we'll have more on record by the autumn.

Don't know if anyone has seen Dave Conroy's blog?--he's circling the world on a Nomad with a 40x17 combination, and reckons a Chainglider would be a good upgrade...but he'd have to change his chainring to accommodate the Hebie.  Dave's blog is a good read:  http://www.tiredofit.ca/2011/03/10/thorn-nomad-mk2/  His account, along with Andy Blance's "Living with a Rohloff", were major influences on my decision to investigate the World of Rohloff.

Thanks, all, for recording & sharing what you've learned.

J.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on January 12, 2013, 11:49:58 PM
Hi John!

You asked, very astutely...
Quote
Dan, at 36 x 17, have you not ventured into The Dreaded Red Zone?
Yes! Indeed I have...by Rohloff's old standards. Very recently, they relaxed those restrictions and 36x17 is no longer forbidden. Instead, it is one of several new lowest-low ratios/cog-'ring combos Rohloff now approve.

Because I was once where you are now in pondering the Rohloff, I'll take a bit more time with my answer in hopes it will prove helpful in reducing the Unknown.

On gearing low...and merits of same
Prior to this -- and especially during the warranty period -- I was indeed careful to stick to one of Rohloff's previously approved lowest-lows, 40x17. Sure, the Rohloff gearbox is expensive, and I wanted to keep my warranty coverage. However, there is something far beyond warranty concerns for me, and that is actual on-tour reliability. I tour alone and unsupported well out of cellphone range in temperature and geographic extremes where a failure could be the end of me. Because I viewed Rohloff's warranty recommendations as an index of reliability, I was loath to exceed them. Now they have been altered, I feel comfortable Rohloff have enough data to certify the hub's reliability at lower ratios. What was speculation is now the closest I can come to fact.

Rohloff's approval of lower ratios confirms Andre's oft-repeated mention of a generous safety margin, as it does for Andy Blance's use of low gearing. It is just nice from my perspective to get the word from On High, direct from Rohloff.

I can say that for my use and in my own experience with low-geared derailleur bikes, going to the 36x17 on my Rohloff-equipped Nomad Mk2 has been a sea-change in making the bike feel more Mine. It compares to getting the "right" handle bars for my needs and preferences. Suddenly, everything feels more natural and familiar, and I have a truly useful and distinct "high range" (quiet operation, "bright" freewheel click) and "low range" (zhoo-zhoo-zhoo noises to a greater or lesser degree when pedaling in most lower gears, but a very soft freewheel click). The high range is what I'm most apt to use on-road...37-80 gear-inches.

With my hummingbirdike 110-120 RPM cadence, I'll be switching most often between 55" direct-drive Gear 11 and 62" Gear 12 (1st overdrive). For headwinds, I'll drop down to my derailleur-familiar 42" and bend my elbows a bit more. For gales (I usually hit afternoon headwinds of 39-45mph/63-72kph in my Great Basin meanderings), I've got the 37" and riding knees-inside-elbows in my beloved into-the-wind shallow-drop/flat-back position.

For hill work and dirt going up and down pronghorn antelope and big-horn sheep trails...unpaved, dirt, rocks the size of shoeboxes and ~24% grades while loaded with 50kg of gear, then I have seven gears in my Low Range to draw upon...from a nice 33" to a near-1:1 25" all the way down to a stump-pulling 15" which isn't as low as it seems (12" is about as low as I have consistently managed with derailleurs when fully loaded on grades  24% and up). For me, the problem has not been keeping upright and making forward progress, it is that the crankarm comes 'round so fast on startup, it is hard to get cleated in before losing forward momentum. The key is to start in a higher gear then immediately drop down, as JimK has frequently suggested...it is just harder with a derailleur and easier to do so with a Rohloff.

Remember: The Rohloff is *already* in gear when you hear the click on shifting, whereas even a good der mech needs about a quarter-turn of the pedals to fully snag and engage the next gear, be it cog or chainring.

So, John, long story short: I'm still preoccupied with the Rohloff warranty, but made the jump to a previously forbidden ratio now it is Rohloff Approved™.

Whazzit like?
John...I was in very much the same position as you are when I started this journey. I had no idea, really, how the Rohloff drivetrain would work in practice, and found this Forum and its experienced members to be a tremendous resource. I can honestly say that despite all my research, careful reading, and questioning, I could not fully grasp the ehm, "Rohloff Ethos" until I got one, and it has required a period of adjustment and learning even then. I have taken another great leap forward in my "comfortableness" and familiarity with the gearbox now the gearing is set more to my liking. Having ridden so many years (35+) "with intent" on derailleur bikes, I have not yet reached that level of familiarity with the Rohloff. I expect to...it is just that not all the "features" come as second nature just yet.

That said, the Experience is remarkable, verging on the sublime at times.

The Good (from my perspective)
1) The operating costs are minimal compared to *modern* 9-sp+ derailleur systems (my old 5-, 6-, and 7-speed thick-cog stuff lasted forever), especially if you choose to keep the complete drivetrain intact and run it into the ground, then reverse cog and 'ring and fit a new chain before running that into the ground in turn. Completely opposite derailleur practice, the parts all wear-in/wear-out together if one goes this route, and the results can be astounding, as shown by Stuart's (Stutho's) experience where he enjoyed 10,000-12,000 miles on the drivetrain before reversing gears and fitting a new chain.

2) Daily maintenance is greatly reduced compared to derailleur drivetrains, a real boon to the tourist who may not have as frequent opportunities to clean the drivetrain as when it is used near home. A Hebie Chainglider would extend this benefit in most use, though the jury is still out as to its appropriateness in the talc-fine dry-lake playa and alkali dust I often encounter. I may well fit a Chainglider for all but desert use, then revert to exposed chainring/cog and bash guard for desert tours. The switch wouldn't be complicated or take much time to accomplish and would be well worth the hassle if I find it necessary. Time and experience will tell.

3) The ability to change gears while at a standstill is something I am growing to love with a loaded touring bike, but have not yet integrated as fully as I intend. The potential here is Huge, and I do wish to exploit it. It is a matter of experience, but I am already getting to the point of assessing a grade before startup, saying "Hmm...this looks like it needs a Gear 4" ...and getting it right the first time.

4) Pausing momentarily between gears is almost hardwired in me after so many years on friction-shifted der mechs, and would be habit even if the Rohloff didn't require it to whatever small degree, especially between Gears 7 and 8. I find having the Rohloff shifter on the T-bar actually helps me in this regard and I still find it "quicker" and even more convenient than downtube or bar-end derailleur shifters. Note: I always paused momentarily when index-shifting as well; old habits are hard to break.

5) With the shifter on the T-bar, I can approach it in a grip (as on straight 'bars) or from the end (as with a doorknob, using my fingertips to "spin" it). Going in from the end, I can cover as many as 7 gears at a single shift. This addressed my initial concerns about the Rohloff's gear-steps being even rather than logarithmic, as I enjoyed with derailleurs. Generally, larger percentage steps are required between low gears to feel a difference; conversely, smaller steps are needed between higher gears for the same effect. Rohloff's steps are all even, and I worried I wouldn't be able to make the "big steps" needed when up- and down-shifting in the lower gears. "Grabbing a fistful of Rohloff" and spinning through several gears in one shot addresses that concern completely for me.

5) As detailed elsewhere on this Forum, compared to my Sherpa's final gearing of 22/32/44 and 12-37 9-sp where I ended up with 13 effective speeds, the Rohloff is comparable, giving me 14 usable gears. While I always enjoyed shifting der bikes (as I do cars with manual transmissions), it is also a joy to not worry about cross-chain issues or looking back inside my right thigh to confirm what gear I'm actually in. I've always loved making gear charts and shifting by them, but to not need one with a Rohloff results in a childlike joy that is hard to describe. Cycling become more elemental. I have gone back to a gear chart with the recent change in ratios, simply 'cos it adds to my joy in riding and brings an element of the familiar into play. I can have more fun with the Rohloff 'cos I also have the chart to play with. The difference is the chart is now a fun accessory rather than an integrated and necessary part of the shifting experience.

6) The Rohloff offers direct-access, sequential shifting. The import of this term took me awhile to fully appreciate. My favorite derailleur setup has always been half-step gearing. It is simple, intuitive, the shifts are easy enough to never need a chart, and it nets the greatest number of usable combinations. However, the loss of suitable front derailleurs has killed halfstep for the masses, and it is hard to engineer a usable half-step with more than 7 cogs on the cassette (my favorite/ultimate was a 7-sp half-step on my Miyata 1000LT; I still have half-step on most of my other bikes).  In contrast, crossover gearing results in a poor number of available combinations, lots of duplicates, and a lot of cross-shifting. Rather than shifting sequentially through the entire range, most people simply treat the three chainrings as "Low", "Cruising/All-'Round" and "Downhill". I found with even my best shot at crossover gearing on Sherpa, by the time I'd cross-shifted, I'd lost enough momentum on hills to make the gear I was aiming for obsolete by the time I found it. In contrast, the Rohloff is like a sequential gearbox in a rally car -- no H- or double-H pattern, just yank and throw the lever. You don't/can't actually "skip" gears, but by the time you "let the clutch out" (stop spinning the Rohloff shifter), you're in whatever gear you've finally selected. Fair warning: This.is.addictive. A bit like steering wheel-mounted paddle-shifters that allow gear pre-selection. Something in the original experience is lost, to be replaced by something "different" and, well, fun in its own way.

The Drawbacks (for me)
There are some drawbacks, none show-stoppers for me. Chief among them is I (me, in my own experience) do find the Rohloff drivetrain to have more drag on coasting than my well-tuned derailleur setup. The difference is greatest on high-speed downhills and insignificant at touring speeds, but it is there. I think it depends on what gear one is in when coasting, but I have not finished my tests and so cannot draw any conclusions at this point. Research is ongoing to the rallying cry of "For Science!".

I wish it was as silent in all gears as my grease-injected freewheels, deliberately rigged for silent running by my preference and so I could sneak up on wildlife. I don't like the "bright-to-brilliant" freewheel clicks in the Rohloff nor the "zhoo-zhoo-zhoo" noise when pedaling in lower gears, but I am getting used to them, and they are also quietening over time with greater use, just as expected.

I do miss the solid engagement of a derailleur system, but the Rohloff gets there all the same in a "softer" way...and engages as firmly with pedaling. All of this is offset by the eerie "instant engagement" of the Rohloff. I still find myself pleasantly surprised by it. I'm expecting to wait for the gear and find I'm already *in* it. Absolutely astounding from my perspective.

The Rohloff shifter -- with the cables adjusted appropriately slack -- does not precisely indicate what gear you're in. Instead, is is approximate between gears. Gear 11 "might" be Gear 12...or really 11. Unlike derailleurs, it doesn't really "matter", but it would be nice for my more spot-on, derailleur-tuned expectations.

I wish the barrel/body/grip of the shifter were larger for better leverage and reduced shifting effort. I'm okay with it, but friends with arthritic fingers always go "Ow! Whyzit so hard to turn?" when they try spinning the shifter (I have the EX external shift-box with thumbscrew attachment, and this is said to have a bit more friction at the hub than does the Rohloff without the EX box (internal shifter with two cable quick-releases, typically routed from above).

That's about it on the demerits, none being of any real concern in my practical use.
-  -  -  -  -
Hebie Say: "38T Chaingliders are OK for 36T and 37T chainrings"
I was in communication with Hebie last week, and their representative specifically advised me...
Quote
The Chainglider is indeed a perfect solution for chain protection and certainly in combination with the Rohloff system. For gear-rings with 36T and 37T you can use the Chainglider front part for 38Teeth. ( 0350F 38 E1) . The rear part with special Rohloff fitting is: 0350R S15 E1. This rear part is usable with sprockets 15T, 16T and 17T.
...so I take this as a green-light to fit a "38T" Hebie Chainglider to my 36T Surly stainless chainring. Please note: The Thorn chainrings are too thick for clearance in the Chainglider, and will result in cosmetic damage to the ring and excess friction from scuffing between the 'ring and Chainglider. There seems to be no such issue when Surly's stainless 'rings are used.

I hope you and others find this useful; it is precisely the information I was seeking when pondering a Rohloff.

Best,

Dan.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: John Saxby on January 13, 2013, 12:44:27 AM
Thanks, Dan, that's really helpful -- didn't realize that Rohloff had eased their approved ratios a bit.

On my current touring bike, my Eclipse, I use a Deore 48-36-24 at the front, and a ditto 12 - 36 cogset, with 700c wheels and 700 x 32 tires (27.5" actual diameter). So, my gear-inch range is 18.3 [rarely used] to 110 [almost never, except unloaded on traffic-free downhills :-) ]  My base gears vary a bit with load, obviously, but are usually around 55 on level windfree tarmac -- maybe a cog lower with a full load, a cog higher without.

I'm reasonably fit at 65, and on a demanding but beautiful camping trip this past summer in the Madawaska Highlands NW of Ottawa, had to resort to my lowest of the low just once, diddling up a 14% grade for about 1.5 kms.  Still, I expect that, er, in the years to come, I'll be glad to have lower gears available. Then again, supply creates its own demand, and after hiking in the Pyrenees in 2011, I could always try some roads in those hills on a Raven Tour with a 16-inch low gear.

So, for sure the 40 x 17 would be rather lower than what I'm running now. The 38 x 17 would be lower still, and both would allow me to do most of my riding in the Rohloff's upper range (8 - 14).  A bonus for the 38 x 17 is that the Hebie Chainglider would fit as well.  I don't have your desert playa conditions to contend with, but have seen enough sand/gravel/rain to want to look seriously at the Chainglider (with the key detail on the Surly stainless chainring duly noted.)

Your summary of the benefits of the Rohloff drive train is very well detailed, and sympathetic too.

Quite looking forward to a discussion on All This with the guys at Thorn when we visit Somerset in March!

Best,

John
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: martinf on January 13, 2013, 08:54:35 AM
Hebie Say: "38T Chaingliders are OK for 36T and 37T chainrings"

Good. So I can go from 38x16 to 36x17 without changing my Chainglider. But only in several years time if I wait for the current parts to wear out.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on January 13, 2013, 03:11:04 PM
Good. So I can go from 38x16 to 36x17 without changing my Chainglider. But only in several years time if I wait for the current parts to wear out.

As is my normal habit, once I have identified the very best component, I bought two Surly 38T chainrings, one to use and one to keep as a spare, and the most beautiful Sugino Cospea 110mm BCD cranks to go with it. At the present mileage, the first chainring will wear out approximately 2023, and the second one in... duh... Even at my more normal mileages, in an abnormally long run of abnormally fine weather such as we enjoyed in the noughties (bring back Global Warming!), the whole point of the stainless steel chainring is that it lasts forever, that it lasts so long one can with confidence conduct experiments like my current zero-extra-lube chain experiment.

And I'd have to buy a new crankset too, as Surly doesn't make the 36T in 110mm diameter fitting. There's nothing at a reasonable price as beautiful as the Cospea in 104mm. (The Deore that Dan and many others have isn't positively beautiful, it is merely negatively not as brutishly clunky as the rest. Sorry, folks, but I'm an artist, and a designer besides, and I'm sensitive — heh-heh — to the shape and proportion of things I use.)

Just as well then I worked out that at present I don't need the extra low range, because I'm doing fine on 38x16, which gives a good, wide, fast (-ish, enough if you're prepared to coast downhill) range on my 60x622 Big Apples, with enough low range to make it up all my hills. (I got caught out twice in the last year and had to push, and one of those occasions was up the longest, steepest hill in West Cork, where I don't ride except when accompanied by my physician -- next time I won't be caught out talking at the bottom of the hill and will make it to or near the top...)

I have my rationalization firmly in place!

Andre Jute
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: rualexander on January 13, 2013, 06:08:20 PM
......And I'd have to buy a new crankset too, as Surly doesn't make the 36T in 110mm diameter fitting.......
Surly stainless rings from 34t up available for 110 bcd here :
http://www.ukbikestore.co.uk/product/54/crsu10/surly-stainless-steel-chainring-110bcd-5-arm.html
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: julk on January 13, 2013, 06:13:25 PM
Andre,
If you need to slow down on hills to give your physician a chance to keep up then you can always move to a 17 cog on the rear :)
Julian.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on January 13, 2013, 06:26:18 PM
Quote
I can go from 38x16 to 36x17 without changing my Chainglider. But only in several years time if I wait for the current parts to wear out.
Hi Martin!

"Careful" as I am to get full value from my purchases, I have occasionally found it worthwhile to make the jump to something else sooner if it better meets my needs. I pondered for some time whether I should stay with 40x17 simply because I already had it, and decided the extra "value in use" of going to 36x17 offset the sunk costs. As it happened, the Surly 'ring cost only USD$24 postpaid new from an eBay vendor, so USD$2/month additional for one year then paid-for, or fractional pennies over the expected lifespan.  

I'm riding the bike a lot and will more, so something that adds to my enjoyment while in the saddle has additional value beyond the cost of whatever it replaces.

I should probably put my near-as-new 38T Thorn 'ring and bash guard up on the Bits For Sale board once I get the Chainglider in place and see if it truly works for me.

Martin, a question for you if I may: Please, can you tell me the length of the chainstays on your RT? I'm pondering whether my Nomad's 470mm/~18.5in chainstays require an extra-long Chaingider or will do fine with the "regular" version. By some measurements, it appears the longer one might be indicated. I presume you're running a Surly 'ring as well?

Andre, Surly make their stainless ring in the following 110mm BCD sizes:
110mm BCD x 34t, 35t, 36t, 38t, 39t, 40t, 42t, 44t, 46t, 47t, 48t, 49t and 50t
Quote
The Deore that Dan and many others have isn't positively beautiful, it is merely negatively not as brutishly clunky as the rest.
No offense taken, Andre; 'tis true! In fact, the entire bike has the brutish appeal of a blunt instrument for getting the job done. Sometimes, beauty is more in a task well-performed; functional aesthetics rather than artistic.

All the best,

Dan.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: martinf on January 13, 2013, 06:51:50 PM
Martin, a question for you if I may: Please, can you tell me the length of the chainstays on your RT? I'm pondering whether my Nomad's 470mm/~18.5in chainstays require an extra-long Chaingider or will do fine with the "regular" version. By some measurements, it appears the longer one might be indicated. I presume you're running a Surly 'ring as well?

450 mm between rear hub axle and bottom bracket centre on the RT.

460 mm for my old 5-speed.

Both bikes have the "regular" Chaingider version, on both bikes measurements will vary somewhat with chain slack adjustment.

Surly ring on the RT after trying with a thicker ring on the old 5-speed.

Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on January 13, 2013, 06:54:18 PM
Thanks to all who straightened me out on the availability of Surly SS chainrings in stump-publling tooth-counts.

Julian: I'd better not prod the fellow; he's fitter than I am!

Andre Jute
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on January 13, 2013, 06:58:03 PM
Thanks very, Martin; I'll contact Hebie again to see what they suggest for my longer 'stays. The EBB is set to the shorter side at the moment, and I'm still getting ~47cm, which might leave too little at the ends for secure attachment of the end-piece cog cover.

All the best,

Dan.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: pelago on January 29, 2013, 03:32:46 PM


(http://static.flickr.com/2238/2194427487_4efa0420d8.jpg)

I am quite with my new custom made Rohloff. I found that my bike is rather similar with the one in the picture, and I too. I am a pastor in a city and mostly bike to my duties. In my bike there are vertical dropouts, no chain gilder, no EBB. The chain ring is 38, and the cog is 16. I will perhaps change to 17. During the summer I have a trailer, Bob Yak. A few times I had to walk up a hill last summer, especially in gravel roads with holes. The Bob Yak has a very small tire, 16 inch. But it is easier to drive even slowly than to walk with a trailer.

I am now 60, 198cm and 82kg; well fit but I very seldom use even 11th gear.

In the snow the lower gears have been very useful even in the city.

I can not stand up when biking even in the hills, the bike feels too small.

This thread was interesting.
Title: Re: Hebie 38T with 36/17 gearing
Post by: revelo on January 30, 2013, 11:36:06 PM
I just finished changing over from my original 42/17 gearing, using a Thorn aluminum 42T chainring to 36/17, using a Surly steel 36T chainring. Chainline with the Thorn chainring was about 55mm, or just over the 54 recommended by Rohloff. Whereas chainline with the Surly chainring was about 52mm. So I added 1.2mm chainring spacers (available at sjscycles) and that brought the chain line to almost exactly 54mm. These measurements are done with a ruler and my measurement error is probably in the range of 1mm. I probably should have used 2mm spacers but I didn't order these, for some reason, and I can't make another order since I'm off on a trip soon.

Because of the much smaller chainring, I now remove 7" from a brand-new 57" chain, rather than 5" as previously. A 50" chain causes the EBB to sit just about in the middle position, so it will probably never be necessary for me to shorten the chain in the field, given that my tours are only about 3000 miles max and I replace my chain at the end of each tour. These are PC830 chains, which I can buy for under $10 (or about £6), so frequent replacement is not expensive for me.

Then I installed the Hebie chainglider for Rohloff 38T version (ordered from sjscycles). As you can see in the picture below, the 38T version is a little large for the 36T Surly chainring, but it seems like it will work. There is clearly some added friction, because before adding the chainglider, the cranks would turn when idling, whereas afterwards they would not. But the friction doesn't seem extreme. There is plenty of clearance at the rear, so no danger of rubbing against the Rohloff shell. Remains to be seen how this gizmo will work on dirt-road tours. My next bicycle tour will be in July.

(http://frankrevelo.com/hiking/biking_nomad2012_hebie38T.jpg)

Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on January 31, 2013, 01:09:06 AM
Hi Frank!

Not to cast a metaphorical stick in the spokes, but I'm a bit concerned about the fit of your Chainglider on the rear portion of the front 'ring. I notice the rear of the chainring is well exposed and this obviates the purpose of the Chainglider. It appears it could pick up excess amounts of dust and grit in your desert use and will draw that inside the case where it will cause problems.

I have a 590M Nomad as well, and have been in contact with Hebie who have helpfully advised me the Extra-Long front unit is appropriate for my chainstay length, rather than the Standard size (they warn a bit of trimming will be needed, but the Standard will be too short for my 'stays). They also advised the 38T front section is appropriate for my 36T 'ring. Apparently, if the Chainglider is connected too tightly with the rear cog cover, the result can be excessive friction of the sort you describe.

Alternatively, if you're at the midpoint in your EBB adjustment, it there may be some length remaining to let the Chainglider out a bit and so better center the front half over the chainring.

All may be well in practice, but it seemed wise to sound a cautionary note in advance of your tour; if it proves to be problematic, it would still be possible to fix it before your departure in July.

Best,

Dan. (...whose comments are well-intended)
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: revelo on January 31, 2013, 03:43:06 AM
Hi Dan,

Sounds like you don't know how the chainglider works. The chainglider I ordered from sjscycles is plenty long enough. However, the front part of the chainglider ALWAYS sits snug against the front part of the chainring, regardless of how long or short it is, because it is designed to wrap the chain. That is, there is a "lip" on the chainglider that encloses the chain. Because of this lip, you can't just push the chainglider forwards, since the lip will catch on the chain at the front of the chainring. So if you use the 38T chainglider with a 36T chainring, you will always have the back part exposed as in my photo, regardless of how long or short the chainglider is and regardless of how you attach the rear section.

BTW I didn't describe "excessive" friction. I said there is enough friction to stop the cranks from turning while idling. This crank turning is due to friction at the seal between sprocket and hub. Evidently, the friction of the chainglider is greater than this hub seal friction, but that is not saying much since the hub seal friction is supposed to be minimal. (Though minimal in a well-lubricated hub, the sprocket-hub seal friction is typically greater than BB internal friction, which is almost nil.) There will obviously be some friction given that the chainglider is resting on the chain.

There would still be openings for dust even with a 38T chainring, though perhaps slightly smaller openings.

I'm going to give the thing a shot and see how it works. I doubt it will make things worse. If it does, I just yank it off and throw it in the trash and I'm back where I was originally. I was planning to carry my usual bottle of chain lube (white lightening epic ride, which is silicone-based) anyway.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on January 31, 2013, 10:29:18 AM
Hi Frank!

Not to cast a metaphorical stick in the spokes, but I'm a bit concerned about the fit of your Chainglider on the rear portion of the front 'ring. I notice the rear of the chainring is well exposed and this obviates the purpose of the Chainglider. It appears it could pick up excess amounts of dust and grit in your desert use and will draw that inside the case where it will cause problems.

I have a 590M Nomad as well, and have been in contact with Hebie who have helpfully advised me the Extra-Long front unit is appropriate for my chainstay length, rather than the Standard size (they warn a bit of trimming will be needed, but the Standard will be too short for my 'stays). They also advised the 38T front section is appropriate for my 36T 'ring.

It seems clear to me, Dan, that if teeth are showing, the thing is misfit. What Hebie is in effect saying is that you should cut the length of the extra-long struts (for want of a better name for the two long sections where only the chain runs) to centre  the Chainglider over the chainring. This is marketing field manure; they must be blushing in the engineering department. Together with Frank's photo it is in fact Hebie's admission that the 36T ring doesn't fit the 38T Chainglider. It is quite clear from Frank's photo that, however carefully you fit the Chainglider, in the best fit all the teeth will show at least in part, rubbing off oil on your trousers, taking in dirt. That defeats both purposes of the Chainglider, cleanliness and low maintenance, as you have noted. More, the Chainglider isn't fixed in any way on the chain, it glides as the name tells you, and therefore there's a millimetre or two of play each way, and that guarantees that no matter how carefully you cut the struts, at one time and another, the slippage might amount to a quarter inch, and the bad fit you're starting with means you end up where Frank is, with teeth showing.

Shame on Hebie for giving this sort of shockingly misleading advice.

Andre Jute
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on January 31, 2013, 10:53:07 AM
Hi Dan,

Sounds like you don't know how the chainglider works. The chainglider I ordered from sjscycles is plenty long enough. However, the front part of the chainglider ALWAYS sits snug against the front part of the chainring, regardless of how long or short it is, because it is designed to wrap the chain. That is, there is a "lip" on the chainglider that encloses the chain. Because of this lip, you can't just push the chainglider forwards, since the lip will catch on the chain at the front of the chainring. So if you use the 38T chainglider with a 36T chainring, you will always have the back part exposed as in my photo, regardless of how long or short the chainglider is and regardless of how you attach the rear section.

Frank, the lip you describe runs the complete circle around the Chainglider chainring cover, and is flexible enough to part of the chainring and to glide over the thinner ends of spider spokes. It is therefore theoretically possible to centre the Chainglider for 38T chainrings over a 36T chainring, as Hebie claims. But it would be a satisfactory solution only if you never rode, pushed or otherwise disturbed your bike. Under any dynamic condition, sooner or later teeth would show whole, as on your bike.

BTW, I've just been to inspect my bike, and even on the 38T chainring, perfectly fitted and proven satisfactory in 4K of rough roads, the 38T Chainglider is not precisely centred: at rest it sits right on top of the chain and is vertically uncentred by about 3mm. In motion it soon centres itself, which is why I haven't before this noticed the minor asymmetry at rest.

There would still be openings for dust even with a 38T chainring, though perhaps slightly smaller openings.

Theoretically correct, but in practice nothing noticeable gets in. I published photographs, on this forum I think, showing how clean the inside of my Chainglider is. I was quite amazed.

I'm going to give the thing a shot and see how it works. I doubt it will make things worse.

Don't you have a bike with cheaper transmission you can try that on? Just asking... I think it possible that the lip will rub off most of the dirt the oil on the exposed teeth pick up. So you may be right, the Chainglider may still offer a good measure of protection, and a Surly chainring is in any event virtually indestructible. I was thinking more of the expensive, and sometimes difficult to get off, Rohloff sprocket.

Good luck.

Andre Jute
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on January 31, 2013, 06:38:31 PM
This is going to require a rethink and further research....

...for Science!

Best,

Dan. (...who is rethinking and researching as he writes this)
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: revelo on January 31, 2013, 08:48:42 PM
Frank, the lip you describe runs the complete circle around the Chainglider chainring cover, and is flexible enough to part of the chainring and to glide over the thinner ends of spider spokes. It is therefore theoretically possible to centre the Chainglider for 38T chainrings over a 36T chainring, as Hebie claims. But it would be a satisfactory solution only if you never rode, pushed or otherwise disturbed your bike. Under any dynamic condition, sooner or later teeth would show whole, as on your bike.

You can certainly center the chainglider on a 36T chainring WITHOUT a chain mounted. WITH a chain mounted, the chain will hold the chainglider snug against the front of the chainring because of the lip. This wasn't obvious to me either at first. It took me a while of tugging and pushing with the chainglider half-installed to figure out why I couldn't push it forwards, until I noticed the lip.

Quote
Don't you have a bike with cheaper transmission you can try that on? Just asking... I think it possible that the lip will rub off most of the dirt the oil the exposed teeth pick up. So you may be right, the Chainglider may still offer a good measure of protection, and a Surly chainring is in any event virtually indestructible. I was thinking more of the expensive, and sometimes difficult to get off, Rohloff sprocket.

No, just one bike. I live in motels now and my storage bin is too small to comfortably store a spare bike, so I sold my old derailleur MTB and with it the cassette removal tool. I had some fond feelings for the former but good riddance to the latter!

Anyway, my whole bike was filthy for most of my three tours so far. For the Lassen tour, the chain was making horrible squeaking noises, it was so filthy, until I got to town and had a chance to clean it with some sort of spray stuff from the discount store. Despite all this dirt, the Rohloff sprocket shows little wear after 5000 miles. I think the secret is that I change the chain after each tour, which is never more than 3000 miles and I soak the chain liberally with lubricant (white lightening epic ride silicone lube) while on tour. My chain has never exceeeded the .75% mark on the chain wear gauge after a tour.

I believe those horribly worn sprockets you sometimes see are due to people running a very worn chain, and they do this with Rohloff systems because they can, not because it is such a great idea. It goes against the old derailleur wisdom which was to replace chains frequently so as to avoid changing chainrings and cassettes. Andy Blance apparently runs his chain into the ground, but he also notes that using a succession of cheap chains is also possible. And SRAM PC830 chains ARE cheap here in the United States. I get mine for under $10, including tax and shipping, and I could get them for $8 if I ordered in bulk. So that's $30/year if I take 3 tours, or about £20/year. Aside from sparing the sprocket and chainring, I think frequently replacing the chain is good simply because the chain has more moving parts than the rest of the bike combined and is subjected to a lot of wear and tear even if kept immaculately clean and well-lubricated. Frequent replacement means less likelihood of the chain breaking in the field. Not that I've had this happen to me, and of course I carry some spare links and spare master links just for this contingency.

My main concern about this chainglider was the potential for rubbing the Rohloff hub shell, but that problems seems completely fixed with the current version. As is, the chainglider will protect me from most filth on the chain and that alone probably justifies the weight (250g), since I was already considering getting the Thorn chain guard for this purpose, which supposedly weighs 135g (and also requires changing the bottom bracket, which is a PITA), but that would only have protected me from part of the filth. I keep my pants secured against my legs with velcro straps I sewed to the pants, but I sometime find myself leaning the chain against my leg while stopped and fiddling with the GPS or items in my handlebar bag, and the Hebie will protect against soiling when that happens. So for 115g more than the Thorn chain guard, I get much better protection from dirt. If the Hebie also allows me to dispense with my toothbrush and bottle of chain cleaning fluid (20g + 140g = 160g) by reducing if not eliminating chain filth, then it is a net reduction in weight.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Matt2matt2002 on January 31, 2013, 10:43:29 PM
Sorry to jump in here at the tail end.....
Is there an alternative the the Chainglider?
Something that fits to the frame rather that sit in the chain?

Matt ( who knows little but is eager to learn )
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on January 31, 2013, 11:53:07 PM
Quote
Is there an alternative the the Chainglider?
Something that fits to the frame rather that sit in the chain?
Matt, our friend Andre has the most experience with a variety of chaincases compared to anyone else who is vocal on the Forum. Moreover, he has been generous to share those experiences with us in a variety of articles. Some samples here:
http://www.thorncycles.co.uk/forums/index.php?topic=2467.0
http://www.thorncycles.co.uk/forums/index.php?topic=2233.0
No doubt he will be along shortly to expand further on your question.

Quote
Matt ( who knows little but is eager to learn )
 <-- Matt, this is the sign of a supremely intelligent individual; asking = a mind open to learning. In my opinion, the only foolish question is the one left unasked.  ;)

All the best,

Dan. (...who thinks an open mind beats an open mouth, but sometimes one leads to t'other with revelation bringing the same result)
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on February 01, 2013, 01:36:41 AM
Sorry to jump in here at the tail end.....
Is there an alternative the the Chainglider?
Something that fits to the frame rather that sit in the chain?

Matt ( who knows little but is eager to learn )

Sure, there are alternatives. There's the Dutch plastic enclosed chain case but it needs one or more frame-side fittings. It is not generally suitable for touring. There is also the Utopia Country, which works much better while it works, but isn't suitable for longrange or rough road touring. See the articles Dan has referenced.

i've tried both of those and settled instead on the Chainglider as the sturdiest and most effective of the lot.

Andre Jute
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: revelo on February 01, 2013, 03:20:48 AM
Regarding all this talk of extra-long chaingliders, I simply ordered what is on the sjscycles website and it seems to work. There's some lettering on outside of the front part, near the chainring, 350 38/N. If anything, this version is slightly long. Long enough to make installation more difficult than if it were a few cm shorter, though not so long that I need to cut it.

I was already placing an order with sjscycles for those special shifter cables Dave Whittle discussed, so additional shipping cost was not an issue for me. If I was only ordering the chainglider, it would be a different story, since syscycles international shipping is quite pricey (though all their other prices are very reasonable).

If it turns out that the chainglider doesn't protect the drive chain from dirt, either because I'm using a 36T rather than 38T chainring or because it is simply ineffective against the kind of dirt I encounter regardless of which chainring is used, I'll nevertheless continue to use the front part to protect myself from the chain. The front part alone weighs just 175g and provides much better protection than the 135g Thorn chain guard, so on that basis alone I'd have to recommend the chainglider.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: bazwaldo on March 05, 2013, 11:01:22 PM
Hello everyone,

I have recently received a quote for a Nomad from Thorn bicycles.
Part of the specification I selected was for a Hebie Chainglider.
Thorn have replied saying they do not recommend the Chainglider:-

"We do not recommend the Heebie chainglider because there have been instances where it  has worn grooves in the Rohloff hub shell. (no warranty for this)"

It this really a problem?
Surely when dealing with such expensive kit it is designed to fit and not cause damage to the hub?

Anyone have any views on this?

I hope I have posted in a relevant thread, I searched for Hebie Chainglider and this thread was top of the list.
If there is a serious risk of damaging the Rohloff hub and nullifying the warranty by using the chainglider it's enough to give me the Hebie Geebies!?! :)

The benefits of lower chain maintenance using the chain cover seem obvious.

Regards,
Barry.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on March 05, 2013, 11:09:15 PM
Hi, Barry!

Take a look at this thread: http://www.thorncycles.co.uk/forums/index.php?topic=5051.0 I think it will answer many of your questions.

Hebie have modified their Rohloff-specific Chainglider end pieces so they now clear the Rohloff hub by an adequate margin; Hebie now say no damage will occur if a current model with Rohloff-specific end piece is used.

Congratulations in advance on your impending Thorn ownership; I can just feel the excitement in your post, and wish you all the best. I'm sure you'll find it a wonderful machine! Have you chosen a color and spec/handlebars yet? Looking forward to seeing photos of your new ride in the gallery after you place an order and it arrives.

Best,

Dan.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: bazwaldo on March 06, 2013, 12:04:50 AM
Hello Dan,
Thanks for your reply and link.

It seems to confirm that Hebie makes a Rohloff specific case which should not damage the Hub.
I wonder why Thorn are still very cautious about this?
Also I have not placed an order yet I am just trying to figure out what spec I need and how much it will cost.
The answer is a phenomenal amount!?! :o
It is so dear it gives me a headache thinking about it.

The way I am looking at it is that it would be like a voluntary health insurance to try and maintain fitness as I move into older age.
In 20 years time I would be 75 years old and looking back at my 20 years of marriage to my dear wife, that has absolutely flown by!
It still seems as though we have just met!!
So the Nomad, if I can use it properly, may help prevent me being an expensive burden on the UK NHS as I move into "old Gitdom" :)

Part of the difficulty for me is that while enthusiastically using my Ebike to complete over 12,000 miles since Oct 2010 I don't know if when push comes to shove that unpowered touring would be feasible and enjoyable.
It is a very expensive experiment to run particularly if it did not meet my optimistic expectations.

I have been reading avidly about cycle touring and it all sounds fantastic and the freedom and self sufficiency seems very attractive.
Currently I am on the 2nd volume of Thomas Stevens 1884 tour around the world which I have found to be a fascinating and riveting read.
He was a wonderful writer and terrific fellow, I took him to be an American but it seems he was born and later died in the UK.
He lived into the 1930's so his life overlapped with my own Father who was born in 1930.
Well it is getting late and I have to be up at 4-45am to Ebike into work tomorrow so I wish you and everyone here a very good night.

Thanks again for your helpful posts and wonderful Stewardship of this great forum.
Barry.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on March 06, 2013, 12:12:45 AM
I understand your concerns, Barry. Thorn bikes are a great value and a lot of money, all at once; Quality costs in the short-term, but is cheap in the long-run.

One thing that might ease your mind is Thorn's generous trial period. If you're in the UK, you really do have the option to try the bike for a long period while deciding if it is for you. Perhaps that will take a bit of the pressure off.

Barry, I had a Sherpa Mk2 and now own a Nomad Mk2. If you have any questions about either bike, just give a shout.

Also...several of our members have electified their Thorns, so if it doesn't work for you to ride it purely on muscle power, you have the future option of enjoying the same bike with an assist.

Thanks so much for your kind words!

All the best,

Dan.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: JimK on March 06, 2013, 01:34:45 AM
Maybe I shouldn't be encouraging others to follow in my path of extravagance... but...

One of my guidebooks of late is Younger Next Year. The authors recommend very strongly that folks over 40 or so should be exercising vigorously an hour most every day, 6 out of 7 anyway. 4 days of aerobics and 2 of weight lifting is best, they say.

This really means, for most of us, a significant change of habits. How to motivate that? One trick they suggest is to use a "kedge". Indulge in something extravagant that forces the change. Maybe register for some event, like a tour, that requires training beforehand. Buying a nice bike, that is one of their suggestions.

My sweetheart still thinks I am totally crazy for spending THAT MUCH MONEY on a silly bicycle. But then... I rode 13 days in January, 14 days in February. Let's see how March goes. See, I have to prove to her that the money was not so stupidly spent. Maybe it's a silly game but if it gets me exercising... whatever!
   
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: John Saxby on March 06, 2013, 02:01:12 AM
Welcome, Barry, and enjoy your new bike!  I think that Dan's link speaks to most of the issues on the chainglider--good luck with that!

On the Big Question of aging (dis)gracefully, and the place of 2-wheelers in All That, no worries so long as your health holds up, and bikes will help with that -- "You're always young on the bike."

Cheers,

John

(as of mid-2012, officially an 'Mzee', as the Swahili term has it -- nice connotation of respect for the elders, homage to wisdom/forgiveness for forgetfulness, freebies from The Younger Tendency, etc.)
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: bazwaldo on March 06, 2013, 08:57:18 PM
Thanks all for your comments.
I am going to open a new thread to give my anticipated Nomad spec as it is so far.

Barry.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on March 06, 2013, 11:28:00 PM
Barry, I don't know what's up with Thorn and the Chainglider. Their attitude seems to be about five years behind the facts, which are that Hebie redesigned the Chainglider to make a special non-grating Rohloff specific rear enclosure. As long as you fit the correct Chainglider sections for your hub gearbox, the gearbox case is in no danger. Period. The Chainglider is the nearest thing to a fit and forget component you can come to.

I don't think you can put a price on your health. I gave up the car in 1992 and got a bicycle, and my physicians are convinced it's the only reason I'm alive.

Andre Jute
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: martinf on March 07, 2013, 10:04:46 PM
The Chainglider is the nearest thing to a fit and forget component you can come to.

At first I was sceptical about a chaincase that just sits over the chain/ring/sprocket and is therefore permanently in contact with moving parts.

After 7 months with a non-optimal installation (chain ring thicker than recommended, probably also the fact that I use 1/8 chain on that bike) I can confirm that I no longer notice the Chainglider when riding my old 5-speed hub-geared bike.

But I do appreciate not needing to clean the chain after use in muddy/wet conditions.

I also have a Rohloff-specific Chainglider on the Thorn Raven I bought in November 2012. The installation on this is as recommended by Hebie (thin Surly chainring, 3/32" chain), so I didn't experience the (slight) rubbing sounds I had with the 5-speed at first.

But due to a change to a much more demanding and interesting job, I haven't had much time to ride the Thorn.

Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: julk on March 08, 2013, 12:27:10 AM
Having read the eulogies from Andre, I fitted a chainglider to my Thorn Rohloff bike.

I cleaned the bike recently and was amazed at how much muck was on the outside of the chainglider - runoff from mudguards and spillage past mudflaps. It certainly keeps the chain very clean and should help the transmission parts last a lot longer.

I changed my tyres the other day and found another benefit of the chainglider - removing the rear wheel is much easier as most of the chain is encased in the chainglider. Only the 2 rear sections need to be removed to allow the cleaner chain to be unshipped from the rear cog.

Anyone found any other hidden benefits?
Julian.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: bazwaldo on March 10, 2013, 02:44:37 AM
Barry, I don't know what's up with Thorn and the Chainglider. Their attitude seems to be about five years behind the facts, which are that Hebie redesigned the Chainglider to make a special non-grating Rohloff specific rear enclosure. As long as you fit the correct Chainglider sections for your hub gearbox, the gearbox case is in no danger. Period. The Chainglider is the nearest thing to a fit and forget component you can come to.

I don't think you can put a price on your health. I gave up the car in 1992 and got a bicycle, and my physicians are convinced it's the only reason I'm alive.

Andre Jute

Sorry I did not spot this post sooner after moving my Nomad spec to it's own thread Andre.
Thanks for your reassurance that the Chainglider is unlikely to cause any problems for the Hub case.
It's good to hear that your cycling has proved beneficial for your health as I am sure it is for all of us who regularly indulge in this fun activity.
Before I started Ebiking to work back in October 2010 I felt sure that my circulation in my legs was suffering due to a lack of exercise and the passing years.
More than 12,000 miles later and I feel a lot better thanks to my regular commuting workout.
I still need to lose more weight and introducing new unpowered cycling is likely to help me achieve this especially if I can cut out the bad parts of my diet!

Best wishes,
Barry.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Trikenomad on March 19, 2013, 03:31:10 PM
52/15 on a HPV Scorpion FX recumbent trike, which means a really long chain.  Will be trying to figure out the ideal combo depending on load, terrain and other variables, but as a new owner it will tame me some time and longer distances.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andybg on March 19, 2013, 06:37:27 PM
Welcome to the forum. keep fancying a trike but it never quite makes it to the top of the list. Don't forget that the gearing on the trike will be affected by the smaller size of the rear wheel compared to a 26" wheel.

Andy
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Tigerbiten on March 20, 2013, 07:00:13 PM
52/15 on a HPV Scorpion FX recumbent trike, which means a really long chain.  Will be trying to figure out the ideal combo depending on load, terrain and other variables, but as a new owner it will tame me some time and longer distances.
With a 20" back wheel you'll be looking at 18"-95".

If your not going up silly steep stuff and you don't mind spinning out around 30 mph, it's fine.
But in my opinion not low and high enough for a bent trike.

Double chainrings 52/39 on the front and a 13 sprocket on the back will open the range up to 15"-110".
Will make steep hill climbing slightly easier and give you a few more mph down hill.

Then again I've got a silly range on my bent trike, 12"-156".
Which is great ......  ;D
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Trikenomad on May 20, 2013, 03:46:47 AM
With a 20" back wheel you'll be looking at 18"-95".

If your not going up silly steep stuff and you don't mind spinning out around 30 mph, it's fine.
But in my opinion not low and high enough for a bent trike.

Double chainrings 52/39 on the front and a 13 sprocket on the back will open the range up to 15"-110".
Will make steep hill climbing slightly easier and give you a few more mph down hill.

Then again I've got a silly range on my bent trike, 12"-156".
Which is great ......  ;D

How does the tensioner manage the amount of chainslack resulted from that difference between the chainrings?

 I weigh 65 kg and the trike another 22.
After the first 800 km in various gradients (Spain is not flatland at all) and testing loads between 10 and 30 kg I have reached the conclusion that the 52/15 combo is perfect.  But only for unloaded cruising (max 5 kg of tools, food and water for one day trips).  Once you start adding heavier panniers these hills begin to suck the life out of you.  Anyway,  one other major problem I wasn't aware of is the knee and hip angles that have a lot to say on the recumbent seat. Lower than 90 degrees and in a few hours hell would be unleashed upon the lactose level of leg muscles.
There are quite a lot of different coefficients to calculate differently from the classic DF setup.  So first change for me is shorter cranks,  155mm. Also switched to a 46T chainring to compensate for the increased force necessary for pedaling smaller diameters.
This new 46/15 combo will put me in a 16-84 GI range,  compared to the previous 18-95, but will also allow me to hit the 11th gear sweetspot at around 57 GI. With the 52/15 the 9th was my favourite,  now with the shorter cranks I hope to be able to hit the 11th more often. What I am aiming for is a suitable gearing for self - supported,  loaded touring.

Once again,  the area I ride is just hills, hills,  hills. My lack of training also shows. Any comparison with a classic DF is also out of place (I still ride my hybrid bike once a week ,  in 3 hours it makes me wanna just stop and rest,  whilst on the recumbent I can sit for 8 hours without getting off, I just go slower when I'm tired and recover rapidly)

I wouldn't ever want to see a derailleur again between my feet. Never.  If I will find the need for an extended range will mount a double in front but without a derailleur,  just move the chain by hand on the smaller plate when I'm facing really steep climbs.  Easy to do,  takes about 3 seconds to do it and you dont even have to get off.

Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Trikenomad on May 20, 2013, 04:05:04 AM
Welcome to the forum. keep fancying a trike but it never quite makes it to the top of the list. Don't forget that the gearing on the trike will be affected by the smaller size of the rear wheel compared to a 26" wheel.

Andy

Thanks,

There are some of trikes with 26" rear wheels,  but I opted for a 20" for strength and reliability (fewer spares to carry). Imagine a 20" brompton wheel  with a Rohloff. Much smaller diameter, shorter spokes,  virtually indestructible. No need for speed for me while touring,  on flats I can easily maintain a 35 km/h and on longer descents I simply stop pedaling, just rest or have a snack and enjoy the landscape.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Trikenomad on June 29, 2013, 06:24:14 AM
I went for it and changed the sprocket also and put a new chain,  so:
- previous config was 52/15 with 170mm cranks
- actual config is 46/16 with 155 mm cranks
Considering the 20" wheel, GI range dropped from 18.1-95 to 15-78.8

The difference is huge as I obviously  lost a lot on the highs compared to what I gained on lows.
I am now pedaling with 30 kg worth of panniers spending the similar effort I did for 5 kg panniers with the previous setup.
Improved my cadence from 60 to 90. Dropped my average speed but still good for loaded touring.
The shorter cranks are much more comfortable for the recumbent position,  more relaxed hip and knee angles translate
noticeably into improved overall efficiency.
All appreciations are appropriate and subjective.

Will probably go back to increasing the GI upper range after some serious touring and muscle building but for now I
think this combo is perfect considering my current load and training level.
Next week will hit the road for a long testing and training period,  3 or 4 months on the road before the big tour.
Cheers.

(http://imageshack.us/a/img844/6287/wb35.jpg)

(http://imageshack.us/scaled/landing/849/2eg8.jpg)

(http://imageshack.us/scaled/landing/27/q7v4.jpg)

(http://imageshack.us/scaled/landing/20/tvxd.jpg)
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on June 29, 2013, 07:27:43 AM
Thanks so much for the update on your gearing; even though your needs and application are different, it s helpful to see how the result works for you. Surprisingly, the final gear range is nearly identical to what I enjoy on my Thorn Nomad Mk2 with 36x17T gearing and 26x2.0 tires.

Thanks also for the link to your upcoming big tour. Best wishes on your 3-4 month runup to it, and on the two-year Eurasia tour to follow.

Best,

Dan.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: mickeg on June 29, 2013, 01:42:05 PM
I wrote  a brief note on a different thread with my gearing, might as well list it here too.

I have been building up my Nomad over the past couple months.  For normal use, am using 44t front and 16t rear.  With the tires I currently have on the bike, this gives me a range of 20.2 to 106.4 gear inches.  I normally use a chainguard/bashguard in the outer chainring position and the chainring on inner on a double crankset.  My chainline is off by about 5mm, I did not want my Q factor to be more than about 10 to 12mm wider than on my other bikes, thus I compromised on chainline.

Last summer there were a couple days of very steep climbing in the USA rocky mountains.  With my Sherpa having a lowest gear of 19.2 gear inches, I wished I had lower gearing.  With this in mind I thought that when I set up my Nomad, I would want to be able to switch to a different chainring for the days when I know in advance that there will be some very steep climbing.  I am not using a front derailleur, instead the plan is to only switch chainrings when absolutely necessary.

So, if I go on a trip where I anticipate steep climbing, I intend to remove the chainguard and put a 36t on the inner and the 44t on the outer positions on my double crankset before I leave home.  I also put an extra quicklink in the chain so I can remove (or add) a few links, adjust the eccentric and have lower (or higher) gearing with only a few minutes of work.  The 36t front with 16t rear will give me a range of 16.6 to 87.1 gear inches.

With the low gear of 16.6 gear inches, I find that the slowest that I can ride the bike and keep myself balanced upright correlates to a cadence of about 72 rpm, which I find is an ideal cadence for me.

Since I am using chainrings and Rohloff cog that all have an even number of teeth, I am going to try this theory:
http://sheldonbrown.com/chain-life.html
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on June 29, 2013, 05:10:54 PM
Hi Mickeg!

Sounds like a good solution to keeping the gearing you prefer while allowing for lower gearing when desired for terrain while loaded touring. The quick-link adjustments should work well to adjust chain length. Pavel pondered something similar awhile back as an alternative to adjusting the eccentric to take up the slack in a wearing chain.

In practical use, I don't think a 5mm offset will matter too much, especially given the Nomad's very long chainstays. In derailleur terms, it is about 1 cog offset, not bad over 18.5in/47cm stays. Additoinal wear will be minimal, especially if one uses a stainless chainring.

I noticed Thorn set my Nomad's chainline as if the 'ring were in the outer position, then replaced it with a bash guard, moving the 'ring to the inner position. This will be ideal for me if Hebie produce a 36T Chainglider, as I will simply move the 'ring to the outside and I'll be spot-on. If Hebie delays for long, however, I'll simply juggle the BB spacers when I replace the Shimano external BB with the Phil I have in reserve.

Best,

Dan.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: mickeg on June 29, 2013, 11:22:55 PM
Danneaux,

I found that I do need to adjust the eccentric when I switch chainrings, but not a big deal.

I felt it was more important for me to keep the Q factor similar across bikes so I can find the pedal with my foot to get cleated in when starting from a stop.  I switch bikes often enough that my foot might remember where it was the last time I was on a bike.  In my case the crankset manufacturer recommended a 110mm (square taper) bottom bracket for a normal road bike, I used a 122.5mm.  I have not had any problem yet with my foot landing in the wrong place.

Chainring, I paid less than $11 USD, so if it wears out, no big deal.  
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on June 29, 2013, 11:35:37 PM
Hi Mickeg,

Thanks for the followup on your post.

Yes, I know what you mean; once a person settles in to a comfortable Q-factor...they're reluctant to switch from what feels "right" in such a core way. For some people, this is a critical factor for knee and hip health. For others, it doesn't seem to matter. I think your solution is innovative and will work well for you. 'Might help others, also.

You're correct, the eccentric adjustments are easy even in the field, and USD$11 for a chainring? What a wonderful deal -- virtually disposable, price-wise.

Best,

Dan.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: harlond on August 25, 2013, 03:03:05 AM
First time poster.  I'm running 36/15.  With 165mm cranks and 650b wheels, that's about 17.4-91.5 gear inches.  Probably a little low for how flat it is here.

Velo-Orange Polyvalent frame & fork, Velocity A23 rims.  Didn't mean to get a Rohloff, was planning on an Alfine, but then I came across a great deal on a Rohloff/Schmidt wheel set, and here I am.  Somehow ended up with the gear shifter working backwards, but it works and the bike rides nice and smooth.  Maiden ride in the Anthem Moonlight Ride in Richmond, Virginia, USA, last Saturday.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: JimK on August 25, 2013, 03:06:51 AM
Welcome to the forum!

I have another bike with a Nexus-8 and that shifts the opposite direction from my Rohloff. The switch always throws me off. When I put new shifting cables on my Rohloff recently I was tempted to try to reverse things, but decided not to risk the extra confusion!
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on August 25, 2013, 04:28:16 AM
First time poster.  I'm running 36/15.  With 165mm cranks and 650b wheels, that's about 17.4-91.5 gear inches.  Probably a little low for how flat it is here.

Velo-Orange Polyvalent frame & fork, Velocity A23 rims.  Didn't mean to get a Rohloff, was planning on an Alfine, but then I came across a great deal on a Rohloff/Schmidt wheel set, and here I am.  Somehow ended up with the gear shifter working backwards, but it works and the bike rides nice and smooth.  Maiden ride in the Anthem Moonlight Ride in Richmond, Virginia, USA, last Saturday.

Welcome Harlond. You've done your good deed for today by inspiring me to go for a moonlight ride!
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Huernie on September 21, 2013, 02:13:38 PM
My bike came with 42-16. I do a fair of amount of loaded climbing up some proper steep hills all over West and North Scotland. I also have dodgy knees due to Plica syndrome. About 5000 miles ago I switched to 38-16 which has made things better. I spend far more time in the upper gears (previously, in a head wind I always seemed to spend an annoying amount of time switching between 7 & 8) and the granny now allows me to spin up most gradients (except over the road to Drumbeg where I still was worried about a knee explosion - has anyone out there toured loaded over that SOB??). Might change to a 17 next time?
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on September 21, 2013, 04:21:46 PM
Hi Huernie!

As a data point, I tour on my Nomad Mk2 with a 36x17 combo and have been very happy with it. I'm a spinner and find the ~28mph/45kph top speed @ 120RPM in the 80-inch gear to be fine; I can always coast faster downhill if I wish.

Those low gears are wonderful. My main concern with pedaling higher gears is not the knee explosion itself, but the shrapnel and resulting damage to property and bystanders.  :D

Best,

Dan. (...who likes his 15 gear-inch low when winching 100kg loads of extended supplies up 24% grades)
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Tigerbiten on September 24, 2013, 04:31:18 PM
I've finally got what I think is the ideal gears for my recumbent trike.

Front:- Twin chainring, 53t/38t, on a Schlumpf HSD.
Back:- 21t sprocket on my Rohloff built into a 20" wheel.
Range 9"-172"

Small ring normal drive takes me from ~2 mph up to ~15 mph.
I then change onto the large ring for the range 15-20 mph.
It's low range overdrive then for the range 20-35 mph.
After that its large ring overdrive to ~50 mph.
It's fun being able to pedal down ~10% hills at +40 mph ........... ;D

Main downside is that I can pop the chainrings off the HSD due to the fact they are only held on by a cir-clip if I have to much force on the pedals when I change chainrings.
If I treat it more like a hub gear change, then its ok.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Huernie on May 12, 2014, 10:41:26 PM
Hi Dan

I took your advice and changed to 36-17. Much better! Thanks.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: macspud on July 18, 2014, 12:26:05 AM
I have a 36/16 and will soon be substituting a 32/16 and, if necessary, a 32/17. At my age (75) and level of fitness I have no fear of damaging the Rohloff with excessive torque.

Hello Benchman,

I was just reading through this thread again and noticed your post.
I'm interested to know how you're getting on with your set-up and where you've got to on your chainring-cog combo.

There should have been absolutely no problems using a combination much lower than 36/17 (rohloff recomended lowest (2.1:1)) as they calculate that using a 150kg max force at the pedal. to apply 150kg at the pedal whilst on a recumbant would need powerlifter strength, much easier on a diamond frame and standing on the pedals and even then would be difficult to do for anyone weighing less than 100kg.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: mickeg on July 18, 2014, 03:35:57 PM
Some followup on my post from June 2013:

...
I have been building up my Nomad over the past couple months.  For normal use, am using 44t front and 16t rear.  With the tires I currently have on the bike, this gives me a range of 20.2 to 106.4 gear inches.  I normally use a chainguard/bashguard in the outer chainring position and the chainring on inner on a double crankset. 
...
...  if I go on a trip where I anticipate steep climbing, I intend to remove the chainguard and put a 36t on the inner and the 44t on the outer positions on my double crankset before I leave home.  I also put an extra quicklink in the chain so I can remove (or add) a few links, adjust the eccentric and have lower (or higher) gearing with only a few minutes of work.  The 36t front with 16t rear will give me a range of 16.6 to 87.1 gear inches.

With the low gear of 16.6 gear inches, I find that the slowest that I can ride the bike and keep myself balanced upright correlates to a cadence of about 72 rpm, which I find is an ideal cadence for me.
...

I used the 36 front and 16 rear on a trip this past April where there was a lot of steep climbing.  It was not a loaded touring trip, instead I used the Nomad as a mountain bike with the 36t front.  After the big climbs were done and we did some car camping, I added a few chain links and switched to the 44 front for road riding.  The photo shows the Grand Canyon in the background.  I am very happy with this setup.

Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: rafiki on April 14, 2015, 11:40:07 AM
Reviving an old thread which I found it because my Sterling feels too low-geared for me at the moment.

It's not very hilly around here and I find that I am almost never in gear 1, gear 2 infrequently and yet I feel I am spinning in gear 14 on a moderate downhill. On a typical ride of about 45km the elevation gain according to Strava is only between 40 and 190 metres.

The Sterling has 26 inch wheels of course and the chainring is a Thorn 39T, the Rohloff sprocket has 16 teeth. I don't do any touring or carry any loads.

I began reading the earlier posts in this thread but my eyes began glazing over on about page 2! I don't understand much about the physics of gearing. I'd be grateful if someone could advise me what would be the best modification to make to my setup to gear me up a bit more.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: JimK on April 14, 2015, 03:04:50 PM
Gear 2 is about 13.6 higher than gear 1, and gear 3 again 13.6% higher than gear 2, or 29% higher than gear 1. Sounds like maybe a 20% increase in your gearing would get you in the range you want. You could try switching to a 47 tooth chainring.

I can barely imagine having gears that are too low! Maybe a 45 tooth chainring, just to avoid too much struggle with the occasional steepish incline?
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: mickeg on April 14, 2015, 03:47:32 PM
Try a 44 chainring if a 39 is geared too low in 14th gear.  A 44 would be geared about 12.8 percent higher.  

Thus when you are in gear 1 in the future, that would be very close to being in your current gear 2.  In other words you lose gear 1.  Thus, you would not lose anything on the low end because you said you never use gear 1.

And gearing up that way, your new gear 13 would be very close to your current gear 14, thus you would gain one new higher gear.

Since your rear cog is an even number, half the teeth that normally have a chain link with outer plates will wear differently than the other half of the teeth that have chain links with inner plates.  Thus, if you have a lot of distance (and wear) on your chain and on your cog, it would be best if you keep the chain links with outer plates on the teeth where you currently have outer teeth.  More on this topic here:
http://sheldonbrown.com/chain-life.html

You might want to mark the teeth some how.  I cut a notch in one tooth on the rear cog and one tooth on my even numbered chainring.  I only put the chain links with outer plates on the teeth that I cut a notch in.  It would be best to mark a rear cog tooth before you take your chain off.

Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: rafiki on April 14, 2015, 09:01:45 PM
Thanks both. I was out today and was thinking some more about the requirement. I concluded that it is just one more gear up. I could take more but it's probably unnecessary. So 45 or 44 will do it. I take your point about the number of teeth. I'll make the marks. Much appreciated.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: mickeg on April 14, 2015, 11:00:29 PM
I forgot to mention that if you do not have any left over chain from your last chain change, you will of course need some more chain to use a bigger chainring.  Or more simply a new one.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: JimK on April 15, 2015, 12:08:46 AM
Sounds like you'll need a new sprocket, too! You'll be back to that gravelly sound if you put a new chain on your existing sprocket!
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: rafiki on April 15, 2015, 07:40:02 AM
Yes, thanks. They were both questions I was going to ask today.

I have a few links in the bag of bits supplied with the bike. Is there a formula to calculate the optimum number of links required in a chain for a chainring/sprocket combo?

I could turn the sprocket. There is some wear on the current side. Would you do that or would you fit new?
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: mickeg on April 15, 2015, 01:39:28 PM
There is no magic answer for whether or not you should turn the rear sprocket around or not.  But, if it has only been used on one side I would not buy a new one.  If it was me doing this, I would probably not turn the sprocket around if I added chain links.  But if I put on a new chain, I might consider turning the sprocket around depending on how worn it looks.

When I switch from the 36 to 44 (eight teeth difference), I add two links with inner plates, one with an outer plate and one quick link for a total of four additional links.  If you go with a 44, that is five more teeth, so try adding two links.  If you have a spare quick link, you could try adding one of those and a link with inner plates, thus avoiding having to use a chain tool.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: rafiki on April 15, 2015, 02:54:58 PM
I'm very grateful for all this advice. much appreciated.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Slammin Sammy on April 15, 2015, 07:14:41 PM
This topic intrigues me. I understand why Sheldon Brown recommended using even numbered teeth on both chainring and sprocket, and always replacing the chain in the same phase, but I can't understand why the chain stretch is confined to the outer plate links.

Sheldon said, "Although all of the rollers, and the inner plate projections that locate the rollers wear, the wear is basically the same for all of the rollers, so the center-to-center distance doesn't change on the rollers connected by inner plates."

I'm missing something here. Can someone make sense if this?
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: mickeg on April 15, 2015, 08:16:26 PM
I'll try.

The links with the inner plates hold the round cylindrical parts (or rollers) that actually contact the chain teeth.  Those rollers do not move relative to the plates in use, or if they do move they do not move very much and that results in no or little wear.  Therefore the rollers in an inner plate link stay the same distance apart.  

Think of the links with the outer plates as consisting only of the plates and the pins, all other parts are part of the inner plate links.  The pins wear down over time because each time the chain wraps around a sprocket and unwraps it later, the pin rubs on parts of a link with an inner plate. In the second photo at Sheldons link you can see a badly worn down pin.  The amount of worn off metal on that pin (and also some wear you can't see because it is inside the link where the pin rubbed) is why a chain becomes longer over time.  

People (including me) refer to this as chain stretch, but it does not really "stretch" because the metal does not physically get longer, instead the parts between the links wear down and that extra slop in the bearing surfaces is where the extra chain length comes from.  And most of that extra length (or stretch) happens between the pins which are part of the outer plate links.

I hope I was clear, sorry if I was not.  I once tried to explain this to a bicycle mechanic and he thought I was nuts, so I gave up trying to explain it.  If I was not sufficiently clear here, perhaps someone else can try to explain it.

I once saw a photo of a badly worn Rohloff sprocket (or maybe it was a sprocket from another internally geared hub bike) and every other tooth was worn down more from this type of wear.

And that is why if you put a chain on a worn sprocket with an even number of teeth, if you put the chain inner plates on teeth where there used to be outer plates on those teeth, the chain will no longer be rubbing on the teeth the same way that the teeth and chain had previously worn, which can result in a noisy drivetrain.  It is best to keep using worn parts with each other as they wore down together under the same mechanical forces.

I have no idea why SJS supplies bikes with sprockets with odd numbers of teeth.  When you buy a new Rohloff hub retail, it is supplied standard with 16 teeth.  I suspect that SJS uses 17 teeth instead to try to even out the wear so you do not have to worry about keeping track of which links go on which teeth.  But, I used to work as a bike mechanic before I went to college and got an engineering degree, so I naturally think of things like how to put the chain on a sprocket properly whereas most typical bike owners don't want to think about this level of detail. The typical owner instead just wants to put the chain on and go, or maybe instead pay someone to put the chain on so they can go.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: David Simpson on April 15, 2015, 08:32:53 PM
Thanks, mickeg, for a great answer. As I read your description, it finally made sense to me.

It seems that the reason for having an odd-tooth sprocket is so that all of the teeth wear evenly. However, the problem is that the links in the chain do not wear evenly. By "wear", I mean the wearing of the pin which causes the distance between the centers of the links to increase ("chain stretch"). The outer links wear much more than the inner links, since they are the links that are affected by the wear of the pins. On an even-tooth sprocket, each tooth contacts either an inner link or an outer link, but not both. Therefore as the chain link wears, the tooth can wear at a corresponding rate (the outer links and their teeth at a faster rate than the inner links and their teeth). On an odd-tooth sprocket, each tooth contacts both inner links and outer links alternately. As the inner links and outer links wear at different rates, the tooth will get more and more "out of sync" with links, since it cannot perfectly fit both the inner links and the outer links at the same time.

That also explains why you mark your sprocket to indicate which teeth are for inner links and which are for outer links.

I assume that this discussion also applies to chainrings, not just sprockets?

I read Sheldon's page a few years ago. I need to go back and take another look at it.

- Dave

p.s. And thanks to Sammy for asking a great question.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on April 15, 2015, 09:37:50 PM
Pictures and more discussion here: http://www.thorncycles.co.uk/forums/index.php?topic=4655.msg22907#msg22907

Best,

Dan.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: John Saxby on August 03, 2015, 12:10:46 AM
This last week of July has been not much fun at all, with temps in excess of 30 degrees for each of the first four days, and the humidex regularly over 40.  I spent a pleasant couple of days in the cool of my basement workshop, tidying up a couple of things on my city bike, and--more important and interesting--tweaking the gear ratios on my Raven. I installed a new, smaller chainring, replacing my Surly stainless 38T with a new Surly 36T, so that I now have a 36 x 17 chainring and cog; and added a new chain as well.

On Thursday, the weather broke with huge late afternoon rain-and-thunderstorm, and Friday was a classically beautiful Ontario summer day: 25, dry, sunny with occasional clouds and a 20 kmh wind from the NW. All the miasmas and airborne particulates from the Ohio valley and the gooey moisture picked up as the SW winds crossed the lakes were swept away and faded to just a bad memory. So I took the Raven for a nice 70 km unloaded test ride up into the Gatineau hills across the river, 3 1/2 hours of riding to check out the new gear ratios, covering all but one of the big hills.

The quick report:

1)   The new ring went on quickly and easily.

2)   Getting the chain length and adjustment was more fiddly, but presented no major problems.

3)   The new ratios worked better than I had expected -- the 5 - 6% gear-inch reduction across the 14 gears of the Rohloff let me keep a much better cadence on climbs, and I spent much more time in both the upper range and in gears 10-11-12 than I normally would on this route with the 38 x 17 combination on the Raven.

4)   So, the 36 x 17 is a keeper, and I won't bother re-fitting the 38T ring at the front. I'd planned to do a loaded test ride of the new combination in the more demanding hills of the Madawaska Highlands later in the summer or fall, and may still do that. But I've been so pleased with my first test ride that I can't see any reason to revert to the 38T ring--I think the lower ratios in #s 1 & 2  especially will make the tough hills that much easier.
 
5)   The 38T ring was very little worn after about 4500 kms over less than 2 riding seasons, and the KMC 8.93 silver chain is less than 50% worn. (If anyone finds themselves within shouting distance of Ottawa, and needs a spare Surly stainless 38T ring, 110 mm 5-bolt pattern, let me know. It's yours for a bottle of braai wine, as we used to call it in SA.)

6)   After just less than 5000 kms, the Rohloff is bedding in nicely, and gets quieter as the mileage increases. The freewheel on the descents still makes a bit of a racket: squirrels chattered at me as I sped down the hills in 13th or 14th, raccoons cursed (I assume) in their tongue, and even the usually imperturbable Bear managed the trick of raising an eyebrow while frowning. (Well, I don't know about any of that last sentence, 'cept for the freewheel's wail, but the critters' reaction seems plausible to me.)

7)   Only question remaining is whether to fit the Hebie 'glider onto the smaller ring. I found that the portion of the 'glider covering the rear of the ring was binding a bit, even after I added more slop to the setup at the front end (top-to-bottom and fore-and-aft) by not setting all the tabs into their slots.  I'm thinking to cut out that section (ignoring the fact that the result will look a bit weird) in the hope of getting rid of the friction against the rear part of the chainring, while still keeping the 'glider's frontal coverage against rain and grit.

Some additional notes on the changeover:

First, the change in ratios. I've attached two tables showing the gear-inch ratios for both the 38 x 17 and 36 x 17 setups. My Raven has Mavic XM719 rims and Marathon Supreme 26 x 1.6 tires. The diameter of the wheel + inflated tire is 25.75".  The 36 x 17 shows 54.54 gear-inches in #11, a reduction of just 3 gear-inches from the 38 x 17, or 5.26%. The change in the feel of the bike seemed much more than 5% -- I found it a lot easier to maintain a comfortable cadence on both steep and more gradual climbs. (The Raven was unloaded, but I've ridden my usual training route often enough with the 38 x 17 setup to say that the new ratios felt noticeably better.)

Secondly, changing the ring was dead simple, a matter of maybe 15 minutes to remove the old chain and ring, clean the bolts and add a touch of blue Loctite, and then install the new 36T ring. I left centring the new ring until I had the new chain in place. When I had the new chain in place, I centred the new ring without much difficulty.  Happily, the tight spot was limited and spread across about 10 - 12 cms of the new chain. One smart but not too heavy poke with my glassfilled rubber deadblow hammer did the necessary: tight spot substantially gone.

The only fiddly bit was the fitting of the new chain--getting the balance between the length of the chain and the adjustment of the EBB.  I had hoped to leave the EBB fixing bolts alone, making the changeover just by calculating the ~ 1" difference in chain length required to fit a chainring which was 2T smaller.  Well, no, not quite: I had some not-big-but-still-irritating problems similar to those described by Steve in his Mercury build. Without going through the numerical details, I had to work back and forth between my new chain (92 links, 2 less than the 94 on the old one, which of course had stretched a bit...), the placement of the EBB, and a couple of KMC Quick-links separated by a half-link. I think that, if I have to take a link out of the chain in the future, I'll be able to do so by removing the half-link and one of the Quick-links, and using the EBB to move the shorter chain backwards...Or maybe not. On va voir, as we say.

An intervening variable in all this is that during my short ten-day tour in Eastern Ontario in mid-July, I had noticed a bit of notchiness from time to time in my right crank arm. On a lazy day beside Lake Ontario, I did some close observation and push-and-pull tests on the crank arms, and found a slight but noticeable bit of play on each arm.  Crank bolts were both very tight, but the axle of the BB seemed to move slightly. I thought I might have a worn Shim UN55 BB; not so. I asked Brad at Tall Tree Cycles, my LBS which had built up the Raven for me, for his reckoning of the health of the BB. He checked, and found that one of my 15mm EBB fixing bolts was loose, and that the EBB was thus shifting slightly in the shell. Yikes!  We tightened the offending item, and during the replacement of the chain, I made sure that once the EBB was rotated for the right tension of the new chain, both bolts were fixed with blue Loctite and properly torqued. I then exhaled.

"Properly torqued" required finding a 15mm x 1/4 drive socket. My nice BBB torque wrench, bought from Wiggle Cycles on Andre's well-founded recommendation :-) lacked a socket of that size. I couldn't chase one down quickly in Ottawa, but found one for C$2.99 in, of all places, the online catalogue of Staples Office Supply, but was dismayed to find that they wanted $15 for shipping it from Tronna (??!!).  Instead, I broke one of my usual rules and ordered one from Amazon.ca for $4.99, added a pair of Cane Creek rubberized bar-ends for my city bike for $50, and got the lot for free shipping from some unknown location, all within 48 hrs. Over the winter, I'll buy a couple of spare 15mm x M8 EBB fixing bolts from SJSC.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on August 03, 2015, 01:10:37 AM
Very nice report, John. Now you an see why I am such a devotee of the 36x17 combo, and why I pine for a Chainglider suitably sized to fit a 36T 'ring.

All the best,

Dan. (...whose hopes spring eternal)
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on August 03, 2015, 01:26:22 AM
If I want any stumps pulled out of the ground, I'll send for the Dynamite Rohloff Gang (entry qualification 38x17 or 36x17 gears!).

John, I keep a couple of sets of drive adapters (1/4-3/8-1/2in) so that I can use sockets from bigger sets, or use my bigger torque wrenches on the bike where justified, usually around the crank axle and pedals. If you have two sets so you can get back to the size you start with, these adapters also make a wonderful variable length extender for working on rear brakes without first having to remove the rack, a place where all the official extenders are too long and the unextended tool is deadlocked between the seatstay and the rack, zero movement of the ratchet.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: John Saxby on August 03, 2015, 02:59:12 AM
"Stump-pullers of the world arise! You have nothing to use but your chains."   ;)
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Matt2matt2002 on August 03, 2015, 11:23:19 AM
Used 38T/17T and a 'glider on my recent tour.
4 panniers full plus water and food - so a good weight carried.
And a good few mountains climbed. 4 passes over 3,500m and plenty more to tax the leg muscles.

I found the ring sizes ideal.
And the 'glider ideal for keeping the chain clean.
On several stretches the mud would have wrecked anything else.

I don't think I'll ever tour - or ride - without a 'glider now.
Makes no sense to me - exposing a chain to muck n dust, if it can be covered.
Not sure I would sacrifice a perfect ring combo for the glider - but it would be a close call.

A pal of mine said he would never use a 'glider coz he likes to see the tension / slackness of his chain at all times.

It's easy to remove and I don't find my chain suddenly goes slack to any great degree.
Maybe there is a case for out of sight out of mind - so a regular chain inspection is good practice.
But each to their own.

Matt


Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: John Saxby on August 03, 2015, 02:37:26 PM
Thanks, Matt. Your 'stans tour gave your 'glider & ring/cog combination a tougher test than anything I'm likely to find in these parts.  I'll see how the 36 x 17 goes on loaded rides across steeper hills, but I'm still interested to see if a modified 'glider can be used effectively with the smaller ring.  Frank Revelo tried it with his Nomad in the back country of the US West, if I recall correctly, and threw it away.  Don't expect to have to deal with quite as much mud as you did, nor quite as much dust as our Westerners face.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on August 03, 2015, 05:14:11 PM
I'll be watching eagerly, John. To Noble Experiments!

All the best <and thanks!>,

Dan. (...who appreciates your giving it a try)
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: mickeg on August 03, 2015, 06:51:08 PM
...
An intervening variable in all this is that during my short ten-day tour in Eastern Ontario in mid-July, I had noticed a bit of notchiness from time to time in my right crank arm. On a lazy day beside Lake Ontario, I did some close observation and push-and-pull tests on the crank arms, and found a slight but noticeable bit of play on each arm.  Crank bolts were both very tight, but the axle of the BB seemed to move slightly. I thought I might have a worn Shim UN55 BB; not so. I asked Brad at Tall Tree Cycles, my LBS which had built up the Raven for me, for his reckoning of the health of the BB. He checked, and found that one of my 15mm EBB fixing bolts was loose, and that the EBB was thus shifting slightly in the shell. Yikes!  We tightened the offending item, and during the replacement of the chain, I made sure that once the EBB was rotated for the right tension of the new chain, both bolts were fixed with blue Loctite and properly torqued. I then exhaled.
...

Note the rubber band I use to keep my bolts from coming unthreaded.  I tried the blue Locktite but was unhappy with it over time.  I have not gotten around to cutting new rubber bands from an old inner tube, but plan to.

http://thorncyclesforum.co.uk/index.php?topic=11125.0
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: John Saxby on August 03, 2015, 09:29:00 PM
Thanks, mickeg, I noticed that photo of your Nomad.  Am thinking that's another use for my go-to fixit-thing: QR rubber ties which I get from Lee Valley Tools, the small 4" variety in the photo below.

(I use these for all kinds of things on the bike & in camping:  Extra security holding the pump & its holder to the frame; tensioning the partly-open doors on my tent to their pegs; brake-bands, locking the levers;  tensioning tarp guylines around trees; wrapping front wheel & downtube to stabilize the wheel when the bike's on the repair stand; compressing rain gear, thermarests, etc., to save pannier space; etc., etc. They're inexpensivve, and very durable.  I get them here:  http://www.leevalley.com/en/garden/page.aspx?p=65393&cat=2,43319,33283 (http://www.leevalley.com/en/garden/page.aspx?p=65393&cat=2,43319,33283) -- never seen them elsewhere.)
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on August 03, 2015, 10:38:03 PM
Thanks, mickeg, I noticed that photo of your Nomad.  Am thinking that's another use for my go-to fixit-thing: QR rubber ties which I get from Lee Valley Tools, the small 4" variety in the photo below.

Isn't it always the small repurposed tools and tips and tricks that make your life so much more convenient that you don't even want to remember how you managed before?

Just last week i noticed that Schwalbe holds new tubes rolled in the box with thin rubber bands cut from ... tubes. I take it as a small hint that a) they test tubes and b) they don't sell tested prototypes as new and c) they waste nothing, which makes their prices more palatable.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: John Saxby on August 04, 2015, 01:48:55 AM
Quote
they waste nothing
  Good for Schwalbe, sez I.

Aou'll recall from life in Africa, Andre, the extravagant range of uses people found for old car- and bike-tire inner tubes.  My anti-baboon catapault from Namibia (now used to chase raccoons that get too close to the BBQ) owes its considerable power to a good-quality strip of HD inner tube.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on August 04, 2015, 11:19:55 AM
My anti-baboon catapault from Namibia (now used to chase raccoons that get too close to the BBQ) owes its considerable power to a good-quality strip of HD inner tube.

You're a dangerous man, John Saxby! I fondly remember a square-rubber cattie from the fork of a walnut tree that was blown down in our orchard. Put a small ballbearing in it and it became a teenage Weatherby .460 Magnum. Back then remote farmers kept a baboon as a watchdog; on run of blue fence wire pegged at each end; they were extremely dangerous animals, made a Rhodesian Ridgeback look like a little old lady's lapdog. I imagine you've seen the famous Raleigh poster of a black man pedalling like crazy while chased by a lion in full mane (a stupid mistake to the eyes of anyone who's ever been in Africa); in math class at school, a dreamy boy drew a cartoon of this poster, substituting for the simply-wrong lion an angry baboon.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: John Saxby on August 04, 2015, 07:19:40 PM
Baboons and raccoons seem to be the cross-continental counterparts, Andre. (Some deep symmetry reflected by the double vowels and double consonants, maybe?) (In North America, wolverines are the really tough customers, but their habitat has been so diminished by us humans that they're rarely seen, except in the more remote areas of the NW.)  Sharp claws and teeth both of them, and they're clever, resilient critters, confident and bolshie 'cos they scare the bejeezus out of a lot of people, and they know it. Suburban (and increasingly, urban) dwellers in Canadian cities and towns spend a fair bit of time and money seeking garbage cans which are raccoon-proof.  Raccoons seem to have decided, "Sod the wild, it's disappearing anyway. I'm going to town, where the food is."
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: John Saxby on August 18, 2015, 03:01:16 AM
Snippets and bits from earlier posts on The Question of A 'Glider Mated to a 36T Ring:

Quote
you can see why I am such a devotee of the 36x17 combo, and why I pine for a Chainglider suitably sized to fit a 36T 'ring

Quote
I'm still interested to see if a modified 'glider can be used effectively with the smaller ring.

Quote
I'll be watching eagerly, John. To Noble Experiments!

Well, we have some visual record of the early stages of my experiment. You can judge, gentle readers, whether or not it's "Noble"; the faint of heart, or purist 'glideristas, may want to avert their eyes.

Midweek last week, I made a 60-km ride of about 3 1/2 hours through some steep hill country about 150 kms northwest of Ottawa. I have ridden most of the route before, but I tweaked it a bit this time. I drove to the starting-point with my Raven on the bike rack at the rear of our station wagon, and my ride was pretty much all hills, with very few flat bits. Here's the link to the route, with the altitude profile: http://tinyurl.com/qdndq8k (http://tinyurl.com/qdndq8k) The route began with a steep climb, 14% for 2.5 kms, and ended with a rapid descent down the same hill.

I'll write about the ride, with some photos, in the "Rides of 2015" thread. The issue for this thread was testing my new 36 x 17 Rohloff ratios on some demanding hills, and to do so with a 'glider fitted to the 36T  'ring.

First things first: how did it work?  Pretty well.  The bike wasn't loaded, but I've planned past rides along this route to ensure that I only descended the really big steep suckers, like the 14% hill between Foymount at the top of the escarpment and the Bonnechere Valley. This time I was starting at the bottom...

So, the big 'un I did in 3rd gear.  It's really two hills with a short plateau in between, and the lower hill is the steeper of the two; since I was still fresh, I probably could have managed the upper half in 4th, but why bother?--especially as I didn't really know what was to come on the back half of the ride.  It turned out that there was an even steeper hill on the back half, a short-but-savage ungraded climb out of a valley with a pretty lake.  I had to use 2nd on that, so I guess it was steeper than, say, 15%.  I think I'd have been able to manage both hills on a loaded bike, in 1st gear or possibly second.

I couldn't pick up any difference between the Raven with 'glider on this ride, and the Raven sans 'glider in my earlier tests on easier hills with the smaller front 'ring.

So, how did I fit my 'glider onto the 36T ring?  When it was mounted on the 38T ring I have just replaced, I had noticed evidence of some friction on the portion of the front half of the 'glider which covers the rear section of the chainring. So, I cut that section away with a sharp blade, with the results you'll see in the photos attached below.

I used the two wraps of tape you see aft of the ring to reduce the length of the gap in coverage of the chain in the upper and lower arms of the 'glider which had resulted from my cutting off the plastic covering the rear portion of the 'ring.  Of course not all of the chainring is protected in this setup, but 99% of the chain run itself is protected; and importantly for me, the front part of the chain remains reasonably well-shielded from rain, spray and grit. We'll see how it works in practice.  If I have to clean the chain once or twice a season, I can tolerate that.

Adjusting a 38T 'glider to its new life embracing a 36T ring required only a little fiddling with the teeth and notches at the rear.  Surprisingly, I found the changed appearance quite OK.  I don't know if The Spirit of the 'Glider felt itself diminished and exposed and all, but I tend to be utilitarian about such matters.

In sum: so far it looks OK (to me), seems not have created any undue friction (maybe even did away with some), and offers better weather protection than no 'glider at all. Maybe I should ride to Nova Scotia to check it out?  More reports if & as the evidence creeps/trickles/pours in.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on August 18, 2015, 03:18:46 AM
Vive le bicycle vivisection, John!

Many thanks for creating and participating in this -- yes! -- most noble of experiments. I will look forward to future reports with greatest interest.

Meantime, as the owner of a 36x17 Rohloff and in "pass-hunting" mode, you simply must purchase one of these:
http://www.skymounti.com/html/gb.html
Also available from Amazon in two sizes:
http://www.amazon.com/Sky-Mounti-Inclinometer-26-0-Diameter/dp/B000PHO6K8
http://www.amazon.com/Sky-Mounti-Inclinometer-31-8-Diameter/dp/B004HUAYMI
...and from the good ol' Adventure Cycling Association: http://www.adventurecycling.org/brands/sky-mounti/sp/inclinometer/

I have owned mine for 8 years now, and found them so addictive, they have multiplied like Tribbles and now live on the handlebars of most of my bikes. I would have killed for one back in the days when I setup a local hill-climbing course totaling 10,000ft total elevation gain. Instead, I had to use an angle finder and convert the readings into slope percentages.

Thanks again for contributing so nobly to the Fund of Knowledge with bold courage, 'speermints (experiments), and pittsures (photographs).

All the best,

Dan.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on August 18, 2015, 03:20:35 AM
...as a followup, I wonder if the now detached rear arc of the front section might be reattached using Sugru or JB Weld, simply displaced rearward of its original position. The front arc looks remarkably good....

Best,

Dan.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on August 18, 2015, 11:27:34 AM
Fascinating report, John. I think you might be surprized at how little cleaning you have to do of the chainring and chain, as there is sure to be a wiping action when the chainring reenters the Chainglider. I also like Dan's idea of reattaching the rearmost part of the chainring cover in the correct place for a 36T chainring. The front part now looks tailor-made, dinnit?

Super experiment, John. Congratulations on its successful outcome.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: il padrone on August 18, 2015, 11:56:38 AM
Danneaux, the marvels of this new technological stuff. Some cycle computers (Cateye Adventure, Specialized Speedzone Elite) come ready equipped with a gradient function built-in. Uses the altitude readings to give a gradient measure.

 ;)
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on August 18, 2015, 04:00:21 PM
Quote
Some cycle computers (Cateye Adventure, Specialized Speedzone Elite) come ready equipped with a gradient function built-in.
<nods> Yes -- and marvelous! -- but Frugal Danneaux isn't going to trash a perfectly good cycle computer when a less expensive add-on will do!  ;)

All the best,

Dan. (...who used an original Cat-Eye CC-1000 from 1985 for 20+ years...)
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: John Saxby on August 18, 2015, 04:13:43 PM
Thanks for the helpful thoughts & suggestions, all.  The Skymounti looks like a fascinating wee device -- no batteries, either!

A cycling buddy here has a Garmin with an altimeter and inclinometer, but on a recent ride in the Gatineau, it registered a 6% descent on one hill, and a 9% climb on our return. FWIW, my guesstimate would have been 5 - 6%.  Seems his Garmin does this frequently.

I still have the cut-off sections of the 'glider, so will keep open the option re-mounting them, depending on how things work out with the current setup.  We had a cool damp spring and early summer, but it's been dry since late June.  Might have to go in search of hills and rain -- Brittany? Scotland?
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on August 18, 2015, 04:25:09 PM
All encouragement, John! Go, go!  ;D

<said without even a *hint* of self-interest! ;) >

All the best,

Dan.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: mickeg on August 18, 2015, 04:38:37 PM
Back to the topic of chainring and cog sizes ...

Around home I use 44 and 16 on my Nomad Mk II.  But I am getting ready for a self supported mountain bike trip next month so I switched over to 36 chainring and 16cog.  This will be great for getting up steep hills on my trip, but I spin out every time I go down a hill around town here.  Maybe I should have waited a few more weeks before swapping out chainings and pulling out a few chain links.

Danneaux, the marvels of this new technological stuff. Some cycle computers (Cateye Adventure, Specialized Speedzone Elite) come ready equipped with a gradient function built-in. Uses the altitude readings to give a gradient measure.

 ;)

I have that capability in some of my GPS units.  I hope that the computer you cite is more accurate than the GPS units I have.  They are terrible at figuring out the slope.  Two of my GPS units have pressure sensors so they should be able to read changes in elevation better than the ones that use GPS information for elevation.

But for accurate gradient, I will take the inclinometer.  In the photo, the hill was at 20 percent slope, was not easy to hold my bike on that slope with one hand while I took the photo with the other.

Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Slammin Sammy on August 21, 2015, 09:44:54 PM

 it registered a 6% descent on one hill, and a 9% climb on our return. FWIW, my guesstimate would have been 5 - 6%.  Seems his Garmin does this frequently.


Mine does too, which I've always put down to barometric variations, mostly diurnal, which bedevil any single point altimeter readings. Just last week, I happened to note on my Edge 800 the 88m high spot on a local track when passed at 10:30 became 95m a few hours later. As I'm pretty certain that level of tectonic activity has ceased in this part of the world, I'm chalking it up to the low pressure change that moved through at the time, coupled with lunar movement. (I think the published datum for that point is 85m, plus ~1m for the height of the instrument.)
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on August 21, 2015, 10:41:12 PM
SkyMountis are bliss-on-wheels. Fascinators. I would be sorely torn to lose mine. They have added so much fun to my rides, read directly, instantly, and consistently and have the side effect of compelling me to search out hills and inclines.

All the best,

Dan.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: hoodatder on January 01, 2016, 11:41:47 PM
Helllllo,

Why is the gear 11 the"critical/desired" gear to achieve?

I imagine it's to do with cadence - spinning?

Being ignorant of inches / gearing I have never ever really taken notice what gear I am cycling in - so long as I can get up most hills, I'm happy.

But, determination, ignorance and pure grit has had a lot to do with it, methinks.

I am going to replace my 40t chainwheel for a Surly 36t chainwheel and leave the 17t sprocket on the rear.

With the new set up, what will gear 11 be equivalent to on my existing set up?

I am not a speed merchant and will happily coast downhill and if gear 11 is THE gear to tootal along in, then I want to be in that club 8).

I have a few questions to ask but I feel your informed answers will not necessitate asking them - I hope

Thanks in advance - going to push some Z's now - nighty night.

Hoot

Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: mickeg on January 02, 2016, 01:30:29 AM
Helllllo,

Why is the gear 11 the"critical/desired" gear to achieve?

I imagine it's to do with cadence - spinning?

Being ignorant of inches / gearing I have never ever really taken notice what gear I am cycling in - so long as I can get up most hills, I'm happy.

But, determination, ignorance and pure grit has had a lot to do with it, methinks.

I am going to replace my 40t chainwheel for a Surly 36t chainwheel and leave the 17t sprocket on the rear.

With the new set up, what will gear 11 be equivalent to on my existing set up?

I am not a speed merchant and will happily coast downhill and if gear 11 is THE gear to tootal along in, then I want to be in that club 8).

I have a few questions to ask but I feel your informed answers will not necessitate asking them - I hope

Thanks in advance - going to push some Z's now - nighty night.

Hoot

Gear 11 is direct drive, the rear wheel turns as if it was a single speed with no internal gearing.  It therefore is slightly more efficient from a mechanical perspective.  I say slightly because the inefficiencies caused by internal friction in all the other gears are so small they are not really noticeable.

That said, it is not that critical that you have gear 11 as your general riding gear, I often ride in gears from 9 to 12 on flat and level terrain, depending on windage.

If you have a 40/17 setup right now and go to a 36/17, that means that your new gear 11 will be very similar to your current gear 12. 

The concept of gear inches goes back to bicycles like the Penny Farthing where your crank was direct drive on the wheel.  Thus, if you have a bike with a gear of 50 inches, you would turn the crankset the same cadence as someone riding next to you on a Penny Farthing if they have a 50 inch diameter wheel.  (I have no idea what size wheels Penny Farthings used, I just used 50 inches as an example.)
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on January 02, 2016, 02:36:35 AM
If you set up your gears so that in gear 11 on the flat you can reach your comfortable long ride cadence, that is the most efficient choice you can make. Gears 12, 13 and 14 are then overdrives for going faster down hills; when you run out of cadence on the downhill, as you say, you cruise at the high speeds courtesy of gravity. (Now that's my kind of cyclist!) Gears 8-10 would then be good for moving off, small inclines, heavy shopping and so on, and gears 1-7 would be a low range for loaded touring on heavy hills, stump pulling at the low end.

As George says, the inefficiencies in the other gears are too small to worry about, so you may as well calculate your gears any other way that seems advantageous to you, regardless of which gear then falls in as your main flatland gear.

Gear 11 is also the most silent gear in the Rohloff box. Even a little noise, if it persists, can cause stress. If you're a long distance tourer, or if you like conversing with the pedalpals while you ride, that is a (rather small) consideration.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: martinf on January 02, 2016, 09:00:38 AM
My current Rohloff setup is 38x16, the recommended minimum Rohloff ratio when I bought my Thorn Raven Tour.  In gear inches this is 17-89 with the tyres I have.

Rohloff now allow a much lower ratio.

Although my current gearing is low enough for nearly anything I have encountered, I would gear even lower for a touring bike if buying now, and ideally set the highest gear to about the same as the highest gear I regularly use (around 75" to 79").

I'd also take into account of whether or not I could fit a Chainglider, which I reckon saves chain maintenance, muck on the chain and the necessity of replacing it 3 times was an irritation on my last long tour with a derailleur bike.

38x17 definitely works, 38x19 or 44x21 might work with a different Chainglider and one of the 2016 model splined Rohloff sprockets.

Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: mickeg on January 02, 2016, 02:47:14 PM
...
Although my current gearing is low enough for nearly anything I have encountered, I would gear even lower for a touring bike if buying now, and ...

For touring on my smaller chainring, I sized the chainring to provide a lowest gear with a cadence of 72 at 3.5 miles per hour (5.63 km/hour) because that is the slowest speed that I can easily maintain balance and that cadence is on the low end of my preferred range. 

With a Schwalbe Marathon Extreme 559X57 tire, that is 16.46 gear inches with 36 chainring and 16 tooth cog (2.25 chainring to cog ratio).  I weigh about 80kg, so that is an acceptable ratio for me.

I have spun out the rear tire on loose gravel in my lowest gear, when climbing a hill that slow it takes no time at all to come to a halt.  And if the hill is too steep for me to sustain 3.5 mph, a lower gear will not help me because I will be walking.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: hoodatder on January 02, 2016, 06:01:06 PM
Evening all,

And thanks to Mickeg and Andre for your informed replies. I know what to be aware of now.

 Ref Re: Hebie 38T with 36/17 gearing
« Reply #127 on: January 30, 2013, 11:36:06 PM »
Quote
I just finished changing over from my original 42/17 gearing, using a Thorn aluminum 42T chainring to 36/17, using a Surly steel 36T chainring. Chainline with the Thorn chainring was about 55mm, or just over the 54 recommended by Rohloff. Whereas chainline with the Surly chainring was about 52mm. So I added 1.2mm chainring spacers (available at sjscycles) and that brought the chain line to almost exactly 54mm.

What is "Chainline" please?
My reason for asking this is:-
I purchased my 2nd hand RST with a 40 x 16 set up - fine. I decided to fit a 17t sprocket last year before cycling through France and France + a bit of Spain this year - fine. However, I decided to refit the original 16t sprocket the other day and upon completion, the chain hung like a clothes line - I kid you not. No amount of adjustment on the EEB would take up the slack. So, I removed 2 links (1 outer + 1 inner - correct?). I then adjusted the EEB to make the chain the correct tension i.e a bit of slack on it. If you can imagine looking at the EEB face on and imagine the hands of a clock, the 2 holes to move the EEB are about 9:55 (5 to 10) - they were originally 01:10 (10 past1). Now, clearly there has been some "stretch", but even to a novice like me this seems an inordinate amount of slack. Further, the chain still seems to sit alright on the cogs. There are now 92 links in the chain. I will be purchasing a new chainwheel and chain so my questions are at the moment for the want of learning, not remedial.

1- Do you think the original chain could have been too long?
2- What is the correct length chain for a 40 x 16 set up on a RST 536L?
3- How do I tell when a chain is past it's sell by date?
4- What defines too tight and too slack?

Sorry if all this is a bit basic, but I want my machine right - not "just that'll do". I'm certain you will all understand.

Thanks

Hoot
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: hoodatder on January 02, 2016, 06:13:20 PM
And here's another question or two,

Earlier in the thread, ( I have tried cutting and pasting but to no avail - memo to myself - "must try harder" )  revelo fitted a 38 Chainglider to a 36 chainring. He thought it was ok but Danneaux Einstein noticed a tad imperfection in the set up. revelo informed him that Hebie said it was ok. Sheldon Jute then poured horse manure on the explanation with his natural aplomb. Danneaux was going to have the 38 Chainglider x 36t set up but was going to look further in to it - for the cause of science.

1- Did Danneaux get the 38 x 36 set up?
2- If he did, did he manage to fit it to an acceptable standard?
3- I've forgotten!


Thanks

Hoot
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on January 02, 2016, 08:24:47 PM
Hi Hoot!
Quote
1- Did Danneaux get the 38 x 36 set up?
Danneaux di'n't! Running a 36t chainring in a 38t Chainglider is simply a bridge too far...the fit is "off" so far, it won't provide the desired protection. Further, the pieces don't match well, so I would need to perform surgery on the Chainglider, only to result in a poor fit for all of it.

For my purposes, a 38t Chainglider won't fit my 36t chainring well enough to give it a try. I hold onto the hope Hebie may yet produce a 36t-specific version, but I'm not holding my breath. For it to be profitable, there must be sufficient demand to offset the costs of tooling and at last correspondence, Hebie's representative was still asking me to send verification Rohloff would allow any chainrings smaller than 36t. There's a way to go yet.
Quote
2- If he did, did he manage to fit it to an acceptable standard?
Danneaux di'n't! Chaingliders are 's'pensive in Danneauxville, so must have a high probability of working and things are not yet there.

My 36x17 gearing must take first precedence; the low is low enough for me, the high high enough, but more importantly Gear 11 and all intermediate gears are just where I want them. It is possible to change my gearing to a combination with larger chainring and sprocket to accommodate a Chainglider, but the cost of changing *only* to fit a Chainglider is too much for me at present, when my current hardware has tens of thousands of kilometers left in it. Money not spent on bike stuff can be spent on bike tours.  :)

If I were starting fresh, then I would select gearing that duplicates mine, and would *also* accommodate a Chainglider.

Quote
3- I've forgotten!
'S'okay! Most things aren't worth remembering.  ;)

All the best,

Dan. (...who still lusts after a Chainglider, but it had better be silent as the moon once fitted)
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: mickeg on January 02, 2016, 08:57:04 PM
...
What is "Chainline" please?
...
3- How do I tell when a chain is past it's sell by date?
...

I think Sheldon handles chainline better than anyone else.  So, I will let him explain.   

http://www.sheldonbrown.com/chainline.html

Rohloff has a fairly wide chainline compared to a typical road bike.  Perfect chainline is not that important, my chainline is off about 5mm intentionally because I did not want my Q factor to be significantly different on my Rohloff bike than on my other derailleur bikes.

https://en.wikipedia.org/wiki/Q_factor_%28bicycles%29

I try to replace my chain when it is 0.75 percent longer than it was when new.  I take my chain off the bike and lay it down flat, then put a small amount of tension on it.  Each link is a half inch.  I am fortunate that I live in a country were rulers with inch scales are common.  I measure some of my chain with a long ruler (I usually use a ruler 48 or 54 inches long) and see how much longer the chain is.  For example, 94 links should measure 47 inches (which is an inch shorter than my 48 inch chain), but when that many links measures 47 3/8 inches (47.375 inches), it is 0.798 percent longer than it should be so I discard the chain.  If it was 47 5/16 inches (or 47.3125 inches) that is 0.665 percent longer and I keep using the chain because it is less than 0.75 percent.

I think most people use their chains until it is a full 1 percent longer, but my chainrings and cogs last longer if I replace the chains at 0.75 percent stretch. 

A chain can be used much longer than 1 percent stretch, but the chainrings and cogs wear out faster, so it is best to avoid that.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: hoodatder on January 02, 2016, 10:41:48 PM
Ah, I've remembered now

3- If Danneaux was to start from new and wanting to use a Chainglider, what would be his ideal set up? ;)

Chainline now understood. The original posting mentioned 54mm and 55mm - that should be 5.4mm and 5.5mm - correct? That's what threw me, honestly.

Now that I have been informed on chain links and lengths etc, I will go and measure my chain - simples :-

But still, to take 2 links out of the original chain is a long stretch of the imagination - or is that chain, don't you think?

Merci Msr Danneaux et Gracias Senor Mickeg. Your delivery was spot on. And in the words of Arnie Schwarzenegger - "I will be back!"

Hoot

Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: hoodatder on January 02, 2016, 10:58:49 PM
Just read Sheldon again - my mistake regarding the 54 mm and 55mm. Apologies to revelo. Got it now.

For some reason I was thinking 54cms and 55cms, which is 22" approx. I am au fait with metric, but sometimes the most simple things  get logged in wrongly :-[

Still. the stupid question was worth asking because mickeg has put me right.

Thanks pal.

Hoot
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on January 02, 2016, 11:19:39 PM
Quote
3- If Danneaux was to start from new and wanting to use a Chainglider, what would be his ideal set up?
I hope to find time to answer in detail later, but right now I am murdering my Christmas tree with a reciprocating saw and stuffing the remains in the trash bin for garbage pickup Wednesday. :o Not to fear; he had a good life from November 27th, when he came to my house and is only now (last evening, actually) dried-out enough to be a fire hazard, so...

Short answer: I would choose a larger chainring (38t, to readily match a Chainglider) and match it with a larger sprocket at the rear so I could duplicate my present 36x17 ratios as closely as possible. Off the top of my head, this would likely be a 19t sprocket, but I'm out in the yard and can't check the particulars so readily on my phone 'cos of the tree blood sap on my fingers.  :P

When cycling, I first set my cadence, which naturally falls into the 110-120RPM range where pedaling is fast and light and kind to my knees (which led a hard life in my youth as crude but effective tools for removing window cranks, bending shift levers, and cracking steering-wheel covers in a car accident). Then, I shift as necessary to keep my cadence within that range. I have good low-speed balance (a legacy of doing track-stands on a Fixed-gear bike) and so I can pedal and remain upright happily at only 2.5mph/4kph. My knees aren't happy much below 85RPM, so I generally dismount when my cadence dips into the low-80s for any length of time.  In the past, I've made my own low derailleur gearing (chainrings as cogs, cogs as chainrings, derailleurs modded as necessary) and found 12.5 gear-inches is my own practical limit. I'm usually pretty happy with 15 gear-inches as my touring low.

A Chainglider sounds a wonderful thing, but would require a real monetary commitment for me to use at this time -- Surly stainless chainrings for my 104BCD crankset are not presently available in sizes above 36t, so I would need a new 110BCD crankset with matching square-taper bottom bracket *and* 38t chainring *plus* a new cog. Hard to justify when my present setup shows scarcely any wear and works superbly for my needs, albeit without a Chainglider. If Hebie decides to make a 36t version, I'm set.

All the best,

Dan.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: mickeg on January 03, 2016, 01:37:25 AM
...
But still, to take 2 links out of the original chain is a long stretch of the imagination - or is that chain, don't you think?
...

I can't really say, every bike with different chainstay length, different combination of chainrings and cogs will be different when it comes to adjusting the eccentric.  I have a larger sized Nomad which probably has a different chainstay length than yours.

Plus, I sometimes use a 44 chainring, sometimes a 36.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: John Saxby on January 03, 2016, 02:47:03 AM
Quote
If one were to start from new and wanting to use a Chainglider, what would be the ideal set up?

Hoot, I've taken the liberty of adapting your question for Dan, about a Rohloff-with-'glider setup.  Let me offer these observations:

     > one can fit a 38T 'glider onto a 36T ring -- see my description earlier in this thread, around #195, I think, on the previous page.

     > note, however, that this setup leaves the rear portion of the chainring exposed.  I haven't had any problems at all with a dirty/muddy chain, but I don't ride in the dusty conditions that Dan often encounters.

     > a 38 x 19 chainring/sprocket ratio gives gear-inch ratios slightly lower than those of a 36 x 17. BUT, Hebie does not currently make a 'glider that will fit over a 19T sprocket.  The 38T 'glider says on its back (inner) side that it will fit a 15T - 18T sprocket.  BUT, there ain't an 18T sprocket available.  Dang! Checkmated if you want a 'glider on a 36 x 17 setup, unless you perform minor surgery as I did.

     > I don't spin at as high a rate as Danneaux -- usually, I'm around 85 RPM -- but I found that that cadence was much easier for me to maintain with a 36 x 17.  There's about a 5% difference between the two setups, but I've found the 36 x 17 noticeably more comfortable. You may have to experiment a bit, trying (say) both a 38T and 36T ring.  It's not too difficult or expensive to do that, though fitting & tensioning the chain can be a bit fiddly.  I think it would be easier to go down to a smaller ring (as I did), thus taking a link or two out of the chain. Or, simply fitting a new chain as mickeg suggests.

     I don't know how much you want to get into this gear-inch stuff.  I do have a spreadsheet showing the different gear-inches with a 38 x 17 and a 36 x 17 set-up, as well as a chart comparing the 36 x 17 with my former touring bike, a derailleur-equipped Eclipse. Happy to send it you you if you like -- send me a Personal Message if so.

Hope this is helpful, and good luck.

John
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: hoodatder on January 03, 2016, 11:32:31 PM
Hi and thanks for all the replies and time taken.

Dan - you have answered my question sufficiently - thanks. Please do not go to the effort of a further explanation. I have a plan - fatal ::)

Mickeg - thanks for your response, but the question was that the original chain on the original sprocket and original chainring had to have 2 links taken out for me to get any tension on it,  so is this a normal type of chain"stretch" or perhaps too long a chain was fitted originally? This is academic as I propose to fit a new chain and chainring soon as per my plan ::)

John - I had read your post 195 (and all the others) a couple of times to get the flavour of the thread. Being a "perfectionist" in my trade - plumbing & heating - I try to adopt the same attitude to most things in life, where reasonable and possible. Therefore, I intend to fit a 38 x 37 with the chain glider but, first of all I intend to see what my relaxed cadence is on my present set up and then equate it to the advice I have been given. If push comes to shove, then I will use your set up and possibly PM you when I make a horlicks of it! In spite of my aforementioned 'perfectionism", I am also of the opinion that ignorance can be bliss and a little knowledge dangerous! To this end, at the moment, I will give your kind offer a body swerve. I'll give you a true instance  of blissful ignorance. Are you sitting comfortably?

In 2005, with advice and little heed to the wallet I specced RT - bombproof! I planned to cycle from Valence in the Rhone Valley to Finnisterre in NW Spain - yes, the Chemin St Jacques & Compestella. I left home Saturday 05:30 to catch the European Bike Express Bus at Sheffield. This bus deposited me in Valence on Sunday 05:30 with 35kg of panniers excluding 3 water bottles, bar bag, bike lock, pump, tools in the saddle pouch etc. I made sure I had something to eat the night before at 22.00 - no flies on me  8) So, in the dark I set off, destination Le Puy En Velay via St Agreve. The beauty about it being dark is that you can't the hill (mountain) ahead of you but one feels it a tad on the legs. When dawn had broken, I looked over the side and had an attack of vertigo - jeez, where did this come from. Anyway, onward on upward. By 10:00 the legs were jelly, I was wheezing, going dizzy and then remembered the 2 tiny biscuits pack I had saved from the night before - told you - no flies on me.  8) Reached St Agreve at 12:00 after only 40 miles approx. It's altitude is 1063m and Valence is 73m but the total climb was at least twice as much. Anyway, by way of a celebration and to rejoice at conquering the mountain, I duly had 2 x glasses of beer 50cl of wine with a fine steak - job done. Unfortunately, my arithmetic was wrong somewhere along the line because I thought Le Puy was just a hop, skip and a jump down the road - actually another 40 miles, yes, with some more of those hills!.Still, the Dutch courage was running high, so I gave it some welly. Being the intrepid adventurer, I paid the blazing hot sun no heed. By 16:00 the wheels were all over the place, motorists were driving on the wrong side of the road, people were speaking in a foreign language when I asked for directions - I was gone, totally gone with sunstroke. I struggled into Le Puy up the very very steep cobbled streets with SPD's slipping trying to push my Clydesdale type bike with35kg. I found the monastery and knocked on the door of the adjacent lodgings. Yes, I could stay the night and tomorrow night, cost 14 euros. I gave him 50 and told him to keep the rest. I hauled my 35kg gear up to my dorm, got showered and went to bed, pronto. I woke up at 03;00 with a thumping headache and got out of bed. Not only was I disorientated but I couldn't see. Everything was blurred, I was in hell of a state until i realised that I'd gone to sleep with my contact lenses in and they had stuck to my eyes. Next day was rest day and I'd only just started. So, on the Tuesday, I left Le Puy En Velay and that exit is a baptism of fire as someone said and he wasn't joking. But I got there with my lungs on fire and gasping for breath. Everything was fine for an hour or so and then I hit the descent. Awesome, just awesome. But what goes down goes up and that's not so awesome. So, I arrived at the municipal hostel late pm and got stamped in. "When is he going to start camping?" I hear you ask. Well, the truth is, that in all that kit there wasn't a tent, no sleeping mat, no stove, no plate, no utensils, not even a mug!! ::) Yes, I made the decision the next day to send home the terry towelling robe, the pyjamas, the slippers, the hair dryer, the portable fridge and portable TV etc. And to cap it all, I was sitting next to a doctor at petite dejeuner when he kindly asked me "How was I coping with my asthma? "What asthma?" says I. "Mon ami" he says " You have all ze systems of asthma - zat is my opinion". Well, to quote Clint Eastwood "Opinions are like assholes - everyone's got one!"

So there you are John. Blissful ignorance, determination and pure grit got me through those 2 rather memorable days. Now, I have to make sure I've got my inhaler, tyres are at the correct pressure ad infinitum. Gone are the days when I would jump on the bike and skedaddle off somewhere that's where the little bit of knowledge is dangerous because it play tunes with your psyche  - and I don't like that.

So, to you all, thanks for your advice, keep it coming and see if you can scramble my brains - more than they are anyway.

Bon nuit

Hoot
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: mickeg on January 04, 2016, 01:24:03 AM
...
Mickeg - thanks for your response, but the question was that the original chain on the original sprocket and original chainring had to have 2 links taken out for me to get any tension on it,  so is this a normal type of chain"stretch" or perhaps too long a chain was fitted originally? This is academic as I propose to fit a new chain and chainring soon as per my plan ::)

..... "What asthma?" says I. ...

I do not know.  If the eccentric for your chainstay length and combination of chainring and cog already used up most of the adjustment, maybe that could be possible that pulling some links out to make it work is the only way.  When you pull the chain it will be interesting to see how much stretch it has.  All I can really say is that with my combination, I have not had to remove any links to take up slack, but with my combination of chainring, cog size and chainstay length, with a new chain I have a lot of adjustment remaining and I probably will reach my 0.75 percent limit before I have to pull any links out.

Sorry to hear about the physical condition.  I have my own sets of problems, but I am fortunate that I do not have asthma.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: John Saxby on January 04, 2016, 04:21:58 PM
Hoot, what a great tale (I almost said, in a complimentary way, "What a hoot!")  ;)

The 38 x 17 is a good place to start, and some folks on this forum have found it to be just fine.  It lets you fit a 'glider with no corrective surgery required.  I have learned that my reserves of strength & endurance are eroding faster than the hills of the Canadian Shield where I do a lot of my rides, so the 36 x 17 suited me better.

Keep us posted, and good luck.

John
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: geocycle on January 04, 2016, 04:44:05 PM
Hoot: There 'may' be a slight fly in the ointment.  I noticed in one of your posts you have an RST? I tried fitting a chainglider to my RST after having much satisfaction with one on the RT but it never quite worked.  It did go on but rubs against the seat stay as the clearance is quite tight. This meant that the glide was never as smooth as on the RT and I rubbed the paint off the frame.  If you try it make sure you mask the contact point and be prepared to do some surgery on the end of the glider.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: hoodatder on January 04, 2016, 06:34:04 PM
Hi mickeg,

I have taken off the chain and measured it - can't believe I'm doing this :-[

It is 92 links and should measure 46"  or 1168.4mm when new. It now measures 1174.75mm an increase of 0.55 per cent

Using your theory of a stretch limit of 0.75 per cent = 8.77mm, I have 20 per cent left or 2.42mm of stretch before discarding it. :)

Thanks for that, it is now locked into the memory bank and I WILL use your theory.

As regards the asthma - I ignore it as much as possible and live my life to the full - propping up the bar at the pub and sleeping when it's closed.

Hard life, I know, but thanks for your concern.

Hi John,

Seems that I will have to do corrective surgery as per geocycles post following yours. I now find myself in the same camp as Dan - and he don't drink!!!! The world has gone mad. I still intend to check my natural cadence and ascertain if it's going to be 38x17 or 36x17. Now you get my drift of too much information can be a bad thing and mess with one's wellbeing.

Hi geocycle,

Thanks for the tip off. That would really have brassed me off having to do corrective surgery. After all, it's not that it's aesthetically pleasing when perfectly fitted but the pros outweighed the cons. I don't think I'm prepared to risking it chafe against the frame and the object was to have less maintenance, let alone checking if the masking tape has worn through. Appreciated though - a lot. ;)

Thanks everyone

Hoot



Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: PeteG on May 24, 2016, 05:23:43 PM
Hi all, sorry for dredging up an old thread, but as I'm soon to be purchasing a new Rohloff, I'd appreciate some advice regarding the approved gear ratios for those of us over 100kg: 112, to be precise and slowly becoming lighter, although at 6'7" not likely to get far below 100kg.

The Rohloff is destined to live on my 29er mtb. I've been running it as a dedicated singlespeed for the past three years and have now decided that it's limiting the amount of riding I use the bike for. I'd like the equivalent of a 24x36 lowest gear ( 19.4gi with 56mm tyres ) and have found that using the supplied 16t sprocket with a 40t chainring, my lowest gear will be 20.3gi. I could achieve 19.3gi with a 38x16 combo, or 19.8gi with 39x16. These work out at a factor of 2.375 & 2.437 respectively. Are they really far enough below the recommended 2.5 to be of concern?

I'm not sure how much difference this makes in the real world. I'd like to think the lowest gear I have available on the Rohloff will be suitable for steep climbing on bridalways and forest tracks, especially after a few hours of riding.

The gear ratios shown on the Rohloff site are 32:13, 38:15, 40:16 and 42:17, so factors of 2.461, 2.533, 2.5 and 2.470. Difficult to see much difference between 2.437 and 2.461, but I'm very wary of causing any damage to such an expensive component.

Cheers,

Pete
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: mickeg on May 24, 2016, 06:07:58 PM
Hi all, sorry for dredging up an old thread, but as I'm soon to be purchasing a new Rohloff, I'd appreciate some advice regarding the approved gear ratios ...

This is a timeless topic, resurrecting something that is timeless is just fine.

... I'd appreciate some advice regarding the approved gear ratios for those of us over 100kg: 112, to be precise and slowly becoming lighter, although at 6'7" not likely to get far below 100kg.
...

I never recommend to anyone that they take any action that could void a warranty.  But it sounds like you are in the range of round off error for your ranges.  So, I think you will have to decide for yourself.  If you start out with a chainring that meets the criteria and find out that you want a smaller ring, you could decide at that time.

It is not clear to me if you are putting this on a new frame or a frame you already have, but if you went with a 26 inch wheel that would give you slightly lower gearing and it may make it possible to stay with an approved ratio for your desired gearing.

I never stand on a pedal to accelerate up a hill or start out from a stop, my knees are too fragile for that.  For that reason if I was over 100kg I might be tempted to use an unapproved ratio because I know with certainty that I would never put all 100 kg of weight on a pedal when I stay in the saddle.  And it would be a lot easier to stay in the saddle if I had the lower gearing that allows me to avoid too much stress on my knees.

Good luck.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: PeteG on May 24, 2016, 07:21:02 PM
Quote
It is not clear to me if you are putting this on a new frame or a frame you already have, but if you went with a 26 inch wheel that would give you slightly lower gearing and it may make it possible to stay with an approved ratio for your desired gearing.

It's definitely for a 29er, so that limits my options slightly.

Quote
I never stand on a pedal to accelerate up a hill or start out from a stop

This is a very good point. While I like the idea of plenty of bail-out gears, I think my singlespeed habits will take a while to go away, and with the hub being on a mountain bike, I expect some stomping of pedals will be involved, despite my 'stomp' not being what it once was...

Thanks for the input! Better to play it safe, I think  :)
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on May 24, 2016, 10:44:32 PM
The gear ratios shown on the Rohloff site are 32:13, 38:15, 40:16 and 42:17, so factors of 2.461, 2.533, 2.5 and 2.470. Difficult to see much difference between 2.437 and 2.461, but I'm very wary of causing any damage to such an expensive component.

Pete, I ride a 29er as my everyday bike, and in my street clothes, which I wear for cycling, I weigh near enough 100kg.

There are three things you have to understand about Bernd Rohloff, the designer of the gearbox you want to buy. The first is that he is German manufacturer, and that even among German manufacturers he is a master of CYA, covering his ass (more politely, protecting his brand's reputation for longevity) with extremely conservative usage ratings and service intervals; there are remarks in threads here and there on this forum about precisely how conservative these ratings and service schedules are, and it makes remarkable reading; in any event, Rohloff's permitted chainring/sprocket ratio that determines the torque fed into the box has been reduced twice in the last decade, i.e. Rohloff admitted each time that it could handle more power than previously stated as the unalterable maximum for the ages; I, for one, don't believe we've seen the last relaxation of these still-conservative ratings. The second is that he is a designer of German agricultural machinery intended to serve your great-grandchildren as faithfully as it serves you; a Rohloff is a heavy box not because Herr Rohloff is an incompetent engineer, or not a cyclist (he's very competent indeed, and a cylist as well) but because it is deliberately the antithesis of the "cheap, light and reliable, choose any two" Lotus paradigm. The third is that the Rohloff gearbox is designed to shrug off the abuse of being ridden on sand-dunes and wet beaches because its design was quite literally inspired by derailleur bikes on his honeymoon self-destructing in protest at being ridden on a beach. It was never intended as a refined touring box, but instead is a mudplugger's box; touring installations happened by accident.

While, like George (Mickeg), I would never advise anyone positively to breach the warranty conditions on such an expensive component, I'll tell you what I would do, in consideration of the above: First, I'd keep the supplied sprocket of 16T and run it with a cheap, probably steel, but permitted chainring until after the box is proven. By this I don't mean run in; as the great Chalo Colina said, a Rohloff box runs in at the kind of mileage where a Shimano hub gearbox lies down and dies (I trashed a couple before 5000m). What I mean is that you have to understand that there's quite a bit of hand-fitting in a Rohloff, so it rubs in the gears in the first couple of thousand miles (you'll see quite a bit of ground steel come out in the first oil change -- use a magnet in the dirty oil to see it, or rub the dirty oil between your fingers to feel it). This is also the time when, if it will break, it will break, so you may want it replaced under warranty. After a couple of thousand miles or after the first service at three thousand miles I'd buy the chainring I really wanted and fit it regardless because the chances are that, unless one abuses the box grotesquely, one won't ever require warranty service.

The first table at http://coolmainpress.com/BICYCLINGHebieChainglider.html contains all the gear-inch and speed combinations for each of the Rohloff gears for selected torque transmission (Chainring/Sprocket) sets for a 29er. Ask if you want another ratio calculated and I'll feed it into my spreadsheet.

Good luck.

PS: Better to reopen a relevant old thread than to spray pieces of the same discussion all over the forum. Anyway, this is one of those perennial ever-fresh threads.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: PeteG on May 25, 2016, 11:33:37 AM
Thanks for all the the information, Andre. I have a 42t chainring that can be used initially, so will see how I get on with that.

Quote
It was never intended as a refined touring box, but instead is a mudplugger's box; touring installations happened by accident.

This is certainly good to know, as it will see its fair share of mud.

My current concern is that my usual mtb range will fall between the 30-70gi range, which will see a lot of switching from gear 7 to gear 8. Something I believe is best done more carefully than switching between 1-7 and 8-14?
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: geocycle on May 25, 2016, 12:09:41 PM

My current concern is that my usual mtb range will fall between the 30-70gi range, which will see a lot of switching from gear 7 to gear 8. Something I believe is best done more carefully than switching between 1-7 and 8-14?

To be honest I don't even think about changes now but I suppose you do have to back off slightly across 7 and 8.  If you mess it up you end up in 7 or 14 which is quickly remedied. IME the difference between a 19" or 20" first gear is hardly detectable and I use these gears very rarely compared to the mid range ones -but that's for touring of course.  Personally I'd make sure 8-12 are in the range you use most of the time and be less concerned about the extremes.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: mickeg on May 25, 2016, 03:54:32 PM
...
My current concern is that my usual mtb range will fall between the 30-70gi range, which will see a lot of switching from gear 7 to gear 8. Something I believe is best done more carefully than switching between 1-7 and 8-14?

For shifting, I grew up shifting Sturmey Archer 3 speeds and later switched to the old "ten speeds" that had a 5 sprocket cluster and a cotter pinned double up front.  Those non-indexed derailleur bikes with friction downtube shifters always required care in shifting.  Thus, I learned that you anticipate your shifts and always back off on your pedal pressure when shifting, regardless of what your drive train was.  That has served me well when shifting the Rohloff.

If you regularly shift under load, yes the shift from 7 to 8 or 8 to 7 could be a bit difficult.  That said, when I have been mountain biking, if I was going slow and needed to downshift, it did not really matter much what gear I was in, I always wanted to back off on the pedal pressure which forced me to anticipate my downshifts a little bit more.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: PeteG on May 25, 2016, 08:08:54 PM
Quote
IME the difference between a 19" or 20" first gear is hardly detectable

I expect you're right. I'm probably just over thinking things :)
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: PeteG on May 25, 2016, 08:13:15 PM
Quote
when I have been mountain biking, if I was going slow and needed to downshift, it did not really matter much what gear I was in, I always wanted to back off on the pedal pressure which forced me to anticipate my downshifts a little bit more.

I seem to remember the only real annoyance would be with the front derailleur occasionally refusing to shift*. Apart from that, I was never one to force a shift when riding, so there should be no issues.


*Last time I used gears was before the 1x11 'revolution'.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on May 26, 2016, 12:07:08 AM
My current concern is that my usual mtb range will fall between the 30-70gi range, which will see a lot of switching from gear 7 to gear 8. Something I believe is best done more carefully than switching between 1-7 and 8-14?

7 snf 8 are also the noisiest gears in the box for the first few thousand miles, though that is likely to be of more concern to tourers than to you.

Gear 11, direct drive, is the most attractive gear in the box. It would do well for you to consider the gears 12-14 as overdrives, for fast riding on the road, and to plan your offroad gearing back from gear 11 at 70 sprocket inches for your regular cadence.

For instance, for a cadence of 60 rpm at the pedals, with 60x622 tyres (the full 29er katootie), reading straight off the table I referenced yesterday, your best bet is 42x17, for a ratio of 2.471 (a wee bit safer than Rohloff's own 32:13 ratio of 2.461!), which will give you 29.8 to 72.8 sprocket inches between gears 4 and 11, reserving 12-14 as overdrives for tarmac road work and 1-3 for the steepest bits offroad, presuming you can keep your balance at 5.8kph or a fraction over 3mph in gear 1.

42x16 is close enough to be getting on with.

This is looking up for you already. We need a specific tyre size and cadence to come any closer.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: PeteG on May 26, 2016, 11:08:05 AM
Quote
your best bet is 42x17, for a ratio of 2.471

Coincidentally, while assaulting my credit card with the purchase of the hub this morning, I also ordered a 17t sprocket and a removal tool.

Just checked my tyres and they're 62mm casing width and 56mm casing height/60mm knob height. (76/80mm - 20mm rim height ), so should work alongside your table.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on May 26, 2016, 02:04:29 PM
Congratulations. You'll be a lot happier with a Rohloff.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: mickeg on May 26, 2016, 11:39:51 PM
...
Coincidentally, while assaulting my credit card with the purchase of the hub this morning, I also ordered a 17t sprocket and a removal tool.
...

I hope you get stuff that matches if you are getting two different sprockets, they are transitioning to the new splined sprockets.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: PeteG on May 27, 2016, 08:21:53 PM
Quote
I hope you get stuff that matches if you are getting two different sprockets, they are transitioning to the new splined sprockets.

Ah yes, I was looking at those. Good to see that they have a simple adaptor for the present hub.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: mickeg on May 27, 2016, 11:40:02 PM
I should have mentioned earlier but did not think of it, the new splined sprockets have a different chainline than the old thread on sprockets.  So, if you are calculating a spindle length for your bottom bracket, you might want to make sure you use the right data for your type of sprocket.

For chainline reasons, I am sticking with the old thread on sprockets.  Sprocket removal on a bike tour would not be very convenient, I find removal at home is quite easy with the proper tools.  I bought a spare thread on sprocket a few weeks ago while I can still get them.

Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: PeteG on May 28, 2016, 09:08:27 AM
Quote
the new splined sprockets have a different chainline than the old thread on sprockets.  So, if you are calculating a spindle length for your bottom bracket, you might want to make sure you use the right data for your type of sprocket.

Thanks for that. Having had a quick measure up, it looks as though my chainline is closer to 58mm than 54mm ( outer ring position of a Shimano Hollowtech II external bearing triple chainset ), so I think my best bet is to return the 17t thread-on sprocket, once it arrives, and then order a splined sprocket + sprocket carrier.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: neil_p on July 27, 2016, 01:26:08 PM
I'm just about to switch to a 47x16 for unladen use. I'll switch back to my 40x16 when I do laden touring.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: mickeg on July 27, 2016, 04:26:04 PM
If you consistently use even numbered chainring and sprocket, this may be pertinent to you.  I cut a small notch in one tooth on my chainring and on the sprocket, I always put a link with outer plates on that tooth.
http://www.sheldonbrown.com/chain-life.html

This is why I use even numbers for both of my touring and for my around-home chainrings.  I also use a 16T sprocket.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Reuel on December 23, 2016, 09:45:54 PM
Just started using 48 x 17 magic gear on a Soma Saga frame using the formula from: http://eehouse.org


Photo:
https://goo.gl/photos/FEj6KxqmfktTaBkr9
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on December 23, 2016, 10:22:52 PM
Very nice, Reuel, and it worked out well for you.

How will you handle chain stretch? Do you presently use some half-links and then remove one or more as needed? Or will you swap chainrings or cogs as needed to take up the slack?

Best,

Dan.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Reuel on December 23, 2016, 11:02:55 PM
Hi Dan, yes I'm not thinking long term at the moment! I'm considering the Rohloff DH Chain Guide, as using half links can get messy - plus maybe a dog fang chain catcher.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: RST Scout on January 16, 2017, 11:30:44 PM
This has been a really interesting topic and I have enjoyed reading it.
My new bike has 44T/17T. I was thinking of swapping the rear to a 19T having read what Andy had to say about the subject in the Rohloff brochure (an extra £5). This would give me a range of 16.9-88.3 inches on a 160mm crank and a 26" wheel. My cadence is quite slow at between 60-70 rpm. My favourite gears are around the 51inch mark. On the 44/19 this would be around gear 10 (not the preferred gear 11).
Now having read the previous remarks, I'm wondering if I should keep the 17T and go for a  smaller front, say a 38T or 36T?
What do you think?

Janet
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: mickeg on January 17, 2017, 12:09:04 AM
This has been a really interesting topic and I have enjoyed reading it.
My new bike has 44T/17T. I was thinking of swapping the rear to a 19T having read what Andy had to say about the subject in the Rohloff brochure (an extra £5). This would give me a range of 16.9-88.3 inches on a 160mm crank and a 26" wheel. My cadence is quite slow at between 60-70 rpm. My favourite gears are around the 51inch mark. On the 44/19 this would be around gear 10 (not the preferred gear 11).
Now having read the previous remarks, I'm wondering if I should keep the 17T and go for a  smaller front, say a 38T or 36T?
What do you think?

Janet

You put less tension on the chain when you pedal with a larger chainring.  Thus, if you have larger front and larger back so that the ratio of front to back is the same, chains should last a bit longer.  And, chain wear occurs when each individual pin rotates within the adjacent chain link as the chain wraps and unwraps around a sprocket or chainring.  Thus, a larger sprocket and larger chainring means that the pin rotates slightly less each time the chain wraps around teh chainring or unwraps off the sprocket.  I am not sure if a chain will last longer with more teeth on the sprocket, but that might also occur but I think that would be very minor compared to the other issues.

I have a 16 in the rear, that is the normal size when you buy a Rohloff hub from most sellers, I did not buy my hub from SJS who usually sells 17 instead.  And I wanted to have an even number of teeth so I stuck with a 16.  But if they had made an 18 or 20, I might have bought that sprocket instead.

Whatever you switch to, keep your old parts in case you want them later.  I use smaller chainring for touring than I use for riding around home. 

If you buy the 19 and if you do not have any extra chain links you might have to buy a new chain because the two extra teeth might need more chain.  I am not sure which bike you have or how much more room you have in your eccentric for adjustment. 

If I recall one Thorn model has a smaller eccentric and if you have that bike you might need to ask SJS what will work.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: julk on January 17, 2017, 11:12:42 AM
Janet,
I would recommend the 38x17 setup plus a chainglider.
That way you will never have to buy another chain…
Julian.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Neil Jones on January 17, 2017, 11:49:29 AM
That would be a good chainring, cog combo although I've heard that you can't fit a Chainglider on an RST (especially small frame sizes) due to the tight clearances, although I have not tried it myself.

Neil
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Matt2matt2002 on January 18, 2017, 12:40:35 AM
Janet,
I would recommend the 38x17 setup plus a chainglider.
That way you will never have to buy another chain…
Julian.

I have 38*17 and a Chaingliger.
And I am buying a new chain this week!
Old one done 6,000 miles I think.
I'll check and confirm this tomorrow.

Great piece of mind, having the Chaingliger. Keeps 99% of muck off.
Easy to fit and remove after a few times. Tricky at first to be honest.

Cog combo is great for touring with weight. A bit over geared otherwise.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: RST Scout on January 19, 2017, 07:33:54 PM
That would be a good chainring, cog combo although I've heard that you can't fit a Chainglider on an RST (especially small frame sizes) due to the tight clearances, although I have not tried it myself.

Neil
Oh! I was specifically thinking about a chainglider with the 38/17 combination but my RST will be a 461S, the smallest there is. Maybe I should forget about the chainglider and just go for 44/19.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: lewisjnoble on January 19, 2017, 09:05:46 PM
Hello Janet - I suppose the fact that the RST has tighter clearances etc is part of what contributes to it being a lighter and feeling a more nimble bike. People with chain guards seem very keen on them, but I'm not sure if the folks without them really miss them.  Oops . . . I'll have started a storm here . . . .

I had a Rohloff Raven Tour for 4 years, no chainguard.  The fact that the chain runs in a fixed line, and never falls off (until very worn) means that the whole system keeps clean, in my experience, and is so much easier to keep that way.  Choose the gearing that suits you, likely use etc (i.e. chainring, sprocket) and you will be fine.

I think most Thorn users would say that if you are torn between two ratios / gearings, go for the lower one, and that is certainly my own view.  I reckon it is far worse to run out of low gears when tired or on a hill that to run out at the top end down hill - a personal view.

Good luck

Lewis
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: julk on January 19, 2017, 11:52:07 PM
Janet,
my expr has tight clearances, the chainglider was pushed off vertical at the rear top by the seatstay.
i took a round surform file to that part of the chainglider which was getting pushed over by the seatstay.
Cutting away at the plastic seemed quite brutal and I eventually cut right through at one point.
I used black duck tape to cover the small gap in the chainglider from both sides making it watertight.
The result is a chainglider which fits and works…
Julian.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: RST Scout on January 20, 2017, 01:53:04 AM
Hello Janet - I suppose the fact that the RST has tighter clearances etc is part of what contributes to it being a lighter and feeling a more nimble bike. People with chain guards seem very keen on them, but I'm not sure if the folks without them really miss them.  Oops . . . I'll have started a storm here . . . .

I had a Rohloff Raven Tour for 4 years, no chainguard.  The fact that the chain runs in a fixed line, and never falls off (until very worn) means that the whole system keeps clean, in my experience, and is so much easier to keep that way.  Choose the gearing that suits you, likely use etc (i.e. chainring, sprocket) and you will be fine.

I think most Thorn users would say that if you are torn between two ratios / gearings, go for the lower one, and that is certainly my own view.  I reckon it is far worse to run out of low gears when tired or on a hill that to run out at the top end down hill - a personal view.

Good luck

Lewis

I rather think I'll go with the 44/19 combo. It gives me a low gear of just under 17". Of my current bikes, the lowest gear is 22" (which my LBS said would climb the wall of a house  ::) so 17" is considerably lower. If I need anything lower, I will just have to get off and push and I've done that enough times in my life  ;) I can always alter it at a later date if I need to.
I've never used anything like a chainglider before so I guess I won't miss what I've never had (I hope).
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: mickeg on January 20, 2017, 02:56:30 AM
I rather think I'll go with the 44/19 combo. It gives me a low gear of just under 17". Of my current bikes, the lowest gear is 22" (which my LBS said would climb the wall of a house  ::) so 17" is considerably lower. If I need anything lower, I will just have to get off and push and I've done that enough times in my life  ;) I can always alter it at a later date if I need to.
I've never used anything like a chainglider before so I guess I won't miss what I've never had (I hope).

My Nomad Mk II has a lowest gear of 16.5 or 21.1 gear inches depending on which chainring I use, I use a larger chainring around home and a smaller one on tour.  My Sherpa has a lowest gear of 19.2 gear inches.  I have never felt like I could climb the wall of a house with either bike.

I do not use a chainglider either, so welcome to the club.

Good luck with your bike.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: rualexander on January 20, 2017, 09:15:16 AM
I rather think I'll go with the 44/19 combo. It gives me a low gear of just under 17". Of my current bikes, the lowest gear is 22" (which my LBS said would climb the wall of a house  ::) so 17" is considerably lower.

Your LBS are idiots and have obviously never been cycle touring, or lived anywhere with steep hills.
17" should be low enough but 16" or 15" would be better.

Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: lewisjnoble on January 20, 2017, 12:58:42 PM
That combo sounds fine to me, Janet. My Sherpa (a lightweight build, probably v similar in style and feel to RST) also has lowest gear around 16.5 / 17". I think the only times I have used it have been round the inside corner of v steep hairpin bends, but I have certainly welcomed it then!
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: julk on January 20, 2017, 03:50:57 PM
Janet,
if you go without a chainglider then simply make sure you have a large front mudflap to keep spray and muck off the chainring and chain.

I have a brompton and on that I use Squirt on the chain - it is a wax based dry lube which lets you brush the muck off the chain after a ride.
I have been pleasantly surprised by how well it has worked and it saves me cleaning an oily chain.
Julian
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: RST Scout on January 20, 2017, 11:41:02 PM
Janet,
if you go without a chainglider then simply make sure you have a large front mudflap to keep spray and muck off the chainring and chain.

I have a brompton and on that I use Squirt on the chain - it is a wax based dry lube which lets you brush the muck off the chain after a ride.
I have been pleasantly surprised by how well it has worked and it saves me cleaning an oily chain.
Julian

Large mudflaps are a must with me, always have been. Funnily enough I was just checking Google for them last night. Brooks do a nice one (but at a price).
I too have a Brommie. Thanks for the tip re Squirt.
Cheers,
Janet
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on January 21, 2017, 12:29:41 AM
Janet,

I can surely endorse long front mudflaps as a way to minimize drivetrain maintenance. I've had good luck with mine over decades.  Having used a variety of commercial offerings and materials to make my own, I've now settled on these:
http://www.buddyflaps.com/
Depending on how long my front mudguard is, I will sometimes use a "rear" (extra long) BuddyFlap on the front, trimmed a bit for length.

They are long enough and thick/heavy enough to avoid blowback, so prevent the chainring(s) and chain run from direct exposure to splashed-up water and road debris like fine sand and grit. I found my preferred chain lubricant doesn't get washed off as quickly, so lasts longer.

I attach mine to the outside of the 'guard using blind ("pop") rivets and backing plates to avoid creating a mud-catching shelf inside the 'guard.

If heated with a heat gun or hair dryer on high, the PVC material can be molded 'round the mudguard contour for a very tidy fit.

Best,

Dan.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: julk on January 21, 2017, 10:40:44 AM
Janet,
adding to Dan’s recommendation,
I use a rear Buddyflap and now a Raw http://rawmudflap.uk/ (http://rawmudflap.uk/) front mudflap.
They are all longer than the excellent (if you want leather) Brooks.
Julian
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Mike Ayling on January 21, 2017, 10:53:47 AM

I have a brompton and on that I use Squirt on the chain - it is a wax based dry lube which lets you brush the muck off the chain after a ride.


I have been using squirt for a couple of years now.
It is certainly a "clean" lube but I don't know how it would go in wet conditions.

Mike
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: martinf on January 21, 2017, 12:00:15 PM
For me, front mudflaps are the first item to consider for keeping muck off the chain and bottom-bracket area.

I've also noticed that the chain stays a bit cleaner on bikes with rear hub brakes rather than rim brakes (in my case coaster, roller or drum brakes, but I reckon disk brakes should be the same). The worst rim brakes are those mounted near the bottom bracket, which are placed in just the right position to spray muck all over the chain. My old mountain bike had one of these, a U-brake, which probably accounted for the excessive chain wear I experienced on my 2011 tour. 

Bikes with hub gears stay cleaner (chain not so close to the road) and are easier to clean than derailleur gears (fewer sprockets, no derailleurs). If the chainring/sprocket combination is compatible they may also allow a Chainglider, which I reckon is the best solution for keeping the chain clean and reducing maintenance.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: RST Scout on January 26, 2017, 07:21:24 PM
Liking the Raw mudflaps (as I'm in the UK). I wonder if they would sell me a CTC winged wheel one.
Thanks Guys.

Janet
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: DAntrim on January 29, 2017, 01:42:05 PM
I'll be changing down to a 38T front ring to give 38 / 17 on the mercury, and as I'm also thinking of fitting the chainglider, I did read that the Thorn front rings are to thick. What front ring would fit into the chainglider ?

Carlos
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: rualexander on January 29, 2017, 06:38:30 PM
I'll be changing down to a 38T front ring to give 38 / 17 on the mercury, and as I'm also thinking of fitting the chainglider, I did read that the Thorn front rings are to thick. What front ring would fit into the chainglider ?

Carlos

Surly stainless steel chainrings are a common option for this scenario.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Matt2matt2002 on January 29, 2017, 07:18:58 PM
I'll be changing down to a 38T front ring to give 38 / 17 on the mercury, and as I'm also thinking of fitting the chainglider, I did read that the Thorn front rings are to thick. What front ring would fit into the chainglider ?

Carlos

Surly stainless steel chainrings are a common option for this scenario.

I use a 38 / 17 on my Raven Tour.
Plus the Chainglider.
I fitted the Surly Stainless Steel 'ring at the same time as the 'glider, back in October 2013.
Also a new KMC X1 chain.

I had turned the chain once since October 2013 and last week replaced it with another KMC X1

It had done 6,720 miles with 2 loaded tours.
Both cogs showed no sign of wear.

(Is there a way of measuring this?)

But the chain guage fitted easily in at 0.75 - so I probably should have replaced it earlier.

I like the 38x17 set up. Before that I had 40 x 16. But of course this is down to personal preferance and the kind of riding one does / loads carried.
Matt
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: martinf on January 29, 2017, 08:18:54 PM
Another vote for the thin Surly stainless steel chainrings for use with a Chainglider. I have these on my two Thorn Ravens.

But on the 3rd bike with a Chainglider I have a thicker TA alloy chainring designed for 1/8" chain. Though not recommended, it works nicely for me. Other people have had issues with thick alloy chainrings and a Chainglider.

I haven't heard of a Chainglider being fitted to a Mercury. There may be an issue with the outboard side of the Chainglider fouling the chainstay - ISTR this problem occurs on some sizes of Raven Sport Tour frames.

I have not yet tried to fit a Chainglider on my own Raven Sport Tour as I have a stock of non-compatible sized TA rings to use up, I am currently running 50Tx19T.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: DAntrim on January 29, 2017, 10:16:35 PM
Thanks all, surly stainless it is

I haven't heard of a Chainglider being fitted to a Mercury. There may be an issue with the outboard side of the Chainglider fouling the chainstay - ISTR this problem occurs on some sizes of Raven Sport Tour frames.
The mercury is my main commuter and due to the milage I cover,  I'm looking for low maintenance solution, see I can combine the oil / chain change at the same time + bottom bracket if required, which the chainglider may provide if it fits.

Carlos
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Peter_K on January 30, 2017, 03:58:03 PM
I run into the problem that I might have to shorten my chain during wear, which I do not like.

So I made this calculation (https://docs.google.com/spreadsheets/d/1Gsonb9574uDokDYT814g67BQZZfDOtOaiLepCP7Fi5k/edit?usp=sharing) to determine the sprockets so that they have the required gear ratio, and I also can wear the chain out without shorting it. (I added a second sheet with gear inches for you inch lovers.  :P)

Does anybody know a calculation on the internet that does something similar, so I can check my calculation?
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Matt2matt2002 on January 30, 2017, 05:57:24 PM
This look interesting.
Can you talk me through how I can use it please?
I don't like shortening chains either.
Matt
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: JimK on January 30, 2017, 06:15:28 PM
Wow that is very cool! I thought a bit about chain stay length and how that sets up the initial position of the EBB. Very nice to see this spread sheet!
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Peter_K on January 30, 2017, 06:53:23 PM
@Matt2matt2002

The yellow figures are dimensions of your bicycle and can be measured, or looked up in the Thorn documentation.

The blue figures are what you chose to ride under most strenuous conditions: so probably climbing a mountain.
Climbing the cadence can be lower (for instance 70 tpm) than on flat (about 100 tpm). The speed is the lowest you see during climbs, the margin is added and subtracted to give a bandwidth in which the available gears are acceptable. So for all gears shown and with a cadence  of 70, the speed will be between 5.1 km/hr and 6.1 km/hr (the higher the gear the higher the speed).
The blue figures for the gear inches work similar.

The results are given in three tables:

Chain replacement at:

Chain wear can naturally be measured with devices like this one (https://www.sjscycles.co.uk/tools/park-tool-cc32-chain-wear-indicator/) or this one (https://www.sjscycles.co.uk/tools/mighty-chainwear-indicator/).
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Javier on January 30, 2017, 10:57:23 PM
I have noticed a subtle grinding noise when pedaling off the saddle in very steep slopes (>15%) when the sprocket looked like had to be replaced. Once I replaced it the noise was gone. I sent a picture of the replaced sprocket to SJS mechanics and they told me that I did the change at the correct time (i.e. not too early not too late). So from now on I will keep my ears sharp for a similar grinding sound, which might be an indication that replacement is needed.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Peter_K on January 31, 2017, 09:07:03 AM
@Javier
On my weekend/holiday bikes I replace my sprockets because of the noise too, because I like things quiet.

But mechanically it is not required. If you don't have a chain tensioner you could ride on till there is hardly anything left of the teeth, because the chain has no room to skip. (Unlike with derailleur sprocket)
Most city bikes here in the Netherlands, also mine, are used in that way. When changing the chain, one changes also the sprocket since they are not that expensive (https://www.sjscycles.co.uk/sprockets/shimano-18t-sprocket-for-nexus-geared-hubs-black-73t-2183/) for city bikes.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Javier on January 31, 2017, 03:32:44 PM
Thanks Peter_K
j
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: John L on April 30, 2017, 02:58:11 PM
17t  x 32t  8)
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: pavel on April 30, 2017, 11:32:38 PM
17t  x 32t  8)

Is that a typo?  That would give a low of 13.7 gear inches, and a high of only 71.8 gear inches.  Useful if one travels only through bogs or up 27% grades and does not mind not voiding Rohloff's warranty. I can't go fast enough at a cadence of 120 rpm with a low of 17.9 to keep my ballance - you must be a trapeze artist with amazing balance. Or ... it's a typo?  :)
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Danneaux on April 30, 2017, 11:42:36 PM
Quote
you must be a trapeze artist with amazing balance.
When I was building my own low-gear drivetrains (chainrings as cogs, cogs as chainrings, custom long rear derailleur cages with outsized tension pulleys, brazed-together front derailleur cage,s 4 chainrings, etc) for myself and my late father, I found 12.5 gear-inches 16t or 17t chainring with 36t cog and 700C wheels) was the practical lowest I could handle. Jack (Dad) managed okay with 15.5 gear-inches. Even then, it required a pretty steep hill to balance -- ~24% with a load. We had hoped for a low enough to manage the 31% grades we often encountered on roads and cat-tracks to timber sales. Nope. We couldn't get traction and when we did, the bike kept wanting to "wheelie over". Managed it once to the detriment of my knee on gravel and Jack's elbow on same.  :(

Riding *really* low gears is an acquired skill. Rather than spin-out it is more like a track-stand, where you let the tension of the hill load the drivetrain and work against that with counter-steering to keep balance. Forward speed was about 2-2.5mph/~3-4kmh, tops. Walking might have been faster but not in the pre-SPD plastic-soled racing cleats I wore at the time.

Best,

Dan.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: mickeg on April 30, 2017, 11:58:45 PM
I run a cadence of 72 to about 80 most of the time.  I estimated that the slowest I could balance a bike on an uphill with a load was 3.5 mph (~5.6 km/hr).  I calculated that the chainring I would want for touring was 36 to pair with my sprocket of 16, that gives me a cadence of 72 at 3.5 mph in first gear with a 559X57 Marathon Extreme tire.   But that gearing means I spin out on the long shallow downhills because I don't run my cadence much over 80.  Gearing is 16.5 to 86.5 gear inches.

For around home use, I run a 44T chainring (and 16T sprocket) instead, the hills near home are not steep enough with an unloaded bike to need my 36T touring chainring.  I find the 44T is perfect for around home, as I don't need a gear lower than 1 or higher than 14.  Gear inches is about 20.1 to 105.8.

Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: JimK on May 01, 2017, 05:17:10 AM
One of my goals right from our start in Utah last summer is to ride up to Francis Peak, elevation 9540 feet. The start of the climb is at 4300 feet. I just got up the first little paved part today, building back up from the winter's laziness. That was about 1000 feet of climbing. Last summer the highest I got was about 7200 feet, so about 3000 feet of climbing. Looks like the steepest sections today were about 13%. I glanced a few times at my speedometer and saw maybe 2.3 mph. I know that I will get down around 1.9 or 1.8 mph sometimes. My combo is 38x16. I could use lower gears but I could use higher gears too. What I have, gear-wise, is good enough. Legs and lungs, that's the project!

https://ridewithgps.com/routes/20761751
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: martinf on May 01, 2017, 09:21:45 AM
17t  x 32t  8)

Is that a typo?  That would give a low of 13.7 gear inches, and a high of only 71.8 gear inches.  Useful if one travels only through bogs or up 27% grades and does not mind not voiding Rohloff's warranty. I can't go fast enough at a cadence of 120 rpm with a low of 17.9 to keep my ballance - you must be a trapeze artist with amazing balance. Or ... it's a typo?  :)

Depends how you ride.

My average speed for long distance riding with full touring load in flattish terrain was between 22 and 24 kph in 2011, and much lower in mountain areas. 24 kph corresponds to a 54 inch gear at my target cadence of 90 rpm.

My current lowest gear is 17 inches, on my Raven Tour. I'm fairly sure I could gear lower, but I chose the gear ratios before Rohloff lowered their lowest gear recommendations.
With full front panniers to keep the front wheel down I can ride my 17 inch lowest gear on very steep hills at about 4kph slowest (= about 2.5 mph, so slow walking speed), dropping my cadence to about 50 rpm.
My Raven Tour top gear of 89 inches I only use on downhills, so I could quite well do without it on a luggage-carrying touring bike.

I have higher gearing (18 to 95) on my Raven Sport Tour, but again I probably don't need the 95 inch top.

On my old 5-speed hub gear bike I recently dropped the gearing from 44x21 (36 to 82 inches) to 38x22 (30 to 67 inches).
Both these ring/sprocket combinations are Chainglider compatible, particularly important for me because I currently use that bike in often mucky conditions for survey work, riding on paths, across grass fields, etc. I don't want to risk a Rohloff bike because I often lock and leave the bike and continue on foot, so I put up with the fairly high low gear of 30 inches.
I don't notice much handicap with the very low highest gear of 67 inches on the tarmac stretches. At 90 rpm I do about 30 kph and can increase to about 120 rpm and 40 kph for short periods (negotiating roundabouts in traffic or similar).
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: pavel on May 01, 2017, 04:30:59 PM
Very interesting insights to be gleaned here, reading all of these varied approaches to the problem of how best to get up and down hills.  To add a bit more wood to the fire, I've found that I tend to cycle at a high cadence when going uphill, and a much lower cadence when on flats or downhill. It tends to be about 90-110 when on a climb as I find it less fatiguing as lactic acid does not build up in my legs (turning them into jelly) and on downhills since I don't need or like to go fast (I put the brakes on at about 30 mph - it's hard to enjoy the scenery when one needs to concentrate at higher speeds) I slow to about 60-70 and the change ups seems to let me last longer in a riding day. I break this of course, regularly, if the situation calls for shooting up a small hill and then use the last few seconds of the bottom of a slope to gain momentum with a frenzied spin.

Any comments on that? Might I be doing some of this upside down and backwards?

On a side note, I find small hills, whether gentle or steep, to be fun. It's the long mile long or longer gentle slopes that I find hard and when those long, long stretches turn steep - I find myself justified in appealing to the gods to place a miracle pub every mile.  In fact, if you ask me, that is the problem with cycling in the US of A. Not enough pub density to call this a civilized country.  But never mind, that's another topic.

with my 41 and 17 combo  the lowest ratio is  17.5 gear inches. On longer steep hills I'd start out spinning and then as I tired, I found that as my cadence dropped I would hit about 4 miles per hour and find it not worth the taxation on my body to keep grinding up the hill on the bike.  I was near where I'd find myself moving back and forth two or three feet on the road at those slow speeds and that's just not worth it with traffic.  Getting off and pushing had me going at 2 to 2.5 miles per hour, so I felt that there was no real loss, and it would change up the muscles used and I felt that I could go all day that way longer.

So when I got back I bought a nice steel Surly ring, meaning to raise my lowest gearing up a bit.  Looking at Sheldon Brown's calculator (http://www.sheldonbrown.com/gear-calc.html) it seems that the 17/43 gives a low of 18.3 to a high of 96.5.  I've not been able to cycle for several years, so I have not yet bothered to install this ... but looking at those numbers, right away I think, I don't need that high a top end, and the bottom seems a very small change.  Seeing how some of you approach this, I wonder if maybe I should not have a stab at the opposite direction? Maybe my problem was that the ratio was not low enough and I could not keep my cadence up.  Hmmm.  I wonder now.

Funny how so much effort, time and money is required for the much critical "ultimate" setup, eh?  Wives just don't understand. Mine has even made the mistake of wondering out loud "why not just go ride it, as is?"  Now that was hilarious. :D
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: David Simpson on May 01, 2017, 05:27:03 PM
I've found that I tend to cycle at a high cadence when going uphill, and a much lower cadence when on flats or downhill.

Any comments on that? Might I be doing some of this upside down and backwards?

I ride the same way.

- DaveS
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Matt2matt2002 on May 01, 2017, 05:32:11 PM
Very interesting insights to be gleaned here, reading all of these varied approaches to the problem of how best to get up and down hills.


Of course the gearing is crucial and very personal but while in Sri Lanka last year ( 37*17 on my Raven) I began to engage with the hills on a mental level.

Bear with me...

It was a case of embracing the slopes/hills. There were 3 of us in the equation.

My bike/weight/gearing.
The hill/headwind/slope.
And me/my physical condition/fitness.

I endeavoured to balance the three issues.
It was a mental thing as well as the physics.

Does anyone else talk to themselves while riding? Or talk to their bike? Or the hill?

Well, it got me up them in a happy mood.
 ;)
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: pavel on May 01, 2017, 06:32:43 PM
Very interesting insights to be gleaned here, reading all of these varied approaches to the problem of how best to get up and down hills.




Of course the gearing is crucial and very personal but while in Sri Lanka last year ( 37*17 on my Raven) I began to engage with the hills on a mental level.

Bear with me...

It was a case of embracing the slopes/hills. There were 3 of us in the equation.

My bike/weight/gearing.
The hill/headwind/slope.
And me/my physical condition/fitness.

I endeavoured to balance the three issues.
It was a mental thing as well as the physics.

Does anyone else talk to themselves while riding? Or talk to their bike? Or the hill?

Well, it got me up them in a happy mood.
 ;)


Such an excellent point!  Yes, yes and yes.  I need to find ways of fooling myself into loving hills - where the reality is probably otherwise.  But much of the time making a game of it, or talking to myself, really does the trick.

I don't have a single thing I use, but sort of a range of several different mental activities, which when they work well really help both the climb as well as the enjoyment of the whole day.

long ago there used to be a Canadian commercial for a concept called participAction.  Funny now, I can't remember how it went, but I used to play that over and over and spin to the cadence of the song in my mind, the way they said the word over and over.  It was almost like a trick to get me slightly hypnotized. I sort of know I'm straining but the pain and in fact all of what I'm doing sort of disapears into the distance, as if I were in a slow moving memory.  Sounds odd to describe, but it worked for me.

I also sometimes used to focus and be aware of the muscles and how they were working, and working in tandem with the breathing.  It's almost as if I could slip into a slow moving world again, where I could feel the individual muscles pushing or not pushing.  That is one reason why I've always liked to be clipped-in.  It may be an illusion, but I can get into a zone where I can minutely change up how much I use the different muscles in slightly different ways, resulting in a bit of rest while I'm still full steam ahead, but mostly I think the benefit for me is purely mental, where it takes me out of the pain, and everything slows down.  It used to work a lot better when I used to run because a track is perfectly predictable, and not as well with cycling because I snap out of my trance at every odd thing in front of me - potholes, tree branches, cars etc all make it hard to stay "in the zone". But still.

and then of course there are a few other things, like pretending some announcer is commenting in a fast auctioneer sort of way on the details of my bicycling form - but now the rain has stopped, the sun is out, and Mexican food for lunch awaits at a nearby restaurant. :)

This is a great subject to bring up to touch on Matt ... I'd love to hear more on this if anyone else has any tips on the mental aspect of taming the less favored aspects of our hobby/sport.

Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Matt2matt2002 on May 01, 2017, 07:29:27 PM

This is a great subject to bring up to touch on Matt ... I'd love to hear more on this if anyone else has any tips on the mental aspect of taming the less favored aspects of our hobby/sport.

You summed up my thoughts exactly.
Should we start a new thread?
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: pavel on May 01, 2017, 09:31:08 PM
Yup.  Pronto.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: John Saxby on May 01, 2017, 10:38:58 PM
Pavel, like you & Dave I find it easier to spin up hills at a higher RPM than I'd normally use on the flats.  To do so, though, I had to reduce my original 38 x 17 combination on my Raven to 36 x 17.  So far, that has been fine, the biggest test coming in the Rockies and Cascades last June/July.

I love the high places, and getting there by bike means climbing hills.  I don't especially like climbing and I'm not much into the Challenge Yerself thing, but I don't shy away from the hills, even the big 'uns, now that I have a good ratio.  It's possible that I'll change to a smaller chain ring (35T, or 34T) in the years ahead--that will depend on the places I go, and my reserves.

Going slowly up the climbs in the western mountains last year, Matt, I found myself doing a mix of talking/singing to myself; reminding myself to just keep the front wheel in line by looking a few yards ahead (and not getting distracted by motorists in the mirror); and on occasion, just stopping to eat, admire the view, watch the butterflies, etc. Lots of opportunities to pause on those looong western slopes.

Last week I was riding in the Gatineau Hills across the river for the first time since early November last year (photos and notes to come in a day or two, especially if the rain continues.)  One of the days was April 25, ANZAC Day and Italian Liberation Day.  In tribute, I was singing (after a fashion) Eric Bogle's great anti-war song, "And The Band Played Waltzing Matilda". John McDermott gives a touching performance, here: https://www.youtube.com/watch?v=VktJNNKm3B0 (https://www.youtube.com/watch?v=VktJNNKm3B0)
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: PeteG on March 12, 2018, 10:51:24 PM
Quote
While, like George (Mickeg), I would never advise anyone positively to breach the warranty conditions on such an expensive component, I'll tell you what I would do, in consideration of the above: First, I'd keep the supplied sprocket of 16T and run it with a cheap, probably steel, but permitted chainring until after the box is proven. By this I don't mean run in; as the great Chalo Colina said, a Rohloff box runs in at the kind of mileage where a Shimano hub gearbox lies down and dies (I trashed a couple before 5000m). What I mean is that you have to understand that there's quite a bit of hand-fitting in a Rohloff, so it rubs in the gears in the first couple of thousand miles (you'll see quite a bit of ground steel come out in the first oil change -- use a magnet in the dirty oil to see it, or rub the dirty oil between your fingers to feel it). This is also the time when, if it will break, it will break, so you may want it replaced under warranty. After a couple of thousand miles or after the first service at three thousand miles I'd buy the chainring I really wanted and fit it regardless because the chances are that, unless one abuses the box grotesquely, one won't ever require warranty service.

Well, it's been 22 months and one oil change ( another one not far off ) later and I think I'll try swapping from 42x17 to 38x17, as I'd much prefer an 18-95" range than the current 20-105". I simply never use gear 14 on my 29er mtb; not even on the road, going downhill. I climb some pretty steep hills, and while my lowest gear has worked ok, I like the idea of having one in reserve  :)

Of course, it doesn't hurt that I'm now 1kg under that cursed 100kg weight limit of Rohloff's.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: Andre Jute on March 13, 2018, 01:30:41 AM
Great to hear from you, Pete.

38x17 is now permitted, but you could do even better than that within the current warranty terms, if you really want to go stump-pulling.

From https://www.rohloff.de/?id=1349&L=1 (https://www.rohloff.de/?id=1349&L=1):
"To prevent overstraining the hub, a minimum sprocket ratio of 1.9 must be used. With the available sprockets these minimum possible sprocket ratios are:
~32/17, ~30/16, ~28/15 and ~26/13. ... Larger chainrings can be used without exceptions."

In gear 1, the limit is the lowest speed at which you can keep your balance.

A consideration in the choice of chainrings and sprockets you now hear quite often is whether there is a Hebie Chainglider that fits the chainring/sprocket combo.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: mickeg on March 13, 2018, 01:47:12 AM
Quote
While, like George (Mickeg), I would never advise anyone positively to breach the warranty conditions on such an expensive component, I'll tell you what I would do, in consideration of the above: First, I'd keep the supplied sprocket of 16T and run it with a cheap, probably steel, but permitted chainring until after the box is proven. By this I don't mean run in; as the great Chalo Colina said, a Rohloff box runs in at the kind of mileage where a Shimano hub gearbox lies down and dies (I trashed a couple before 5000m). What I mean is that you have to understand that there's quite a bit of hand-fitting in a Rohloff, so it rubs in the gears in the first couple of thousand miles (you'll see quite a bit of ground steel come out in the first oil change -- use a magnet in the dirty oil to see it, or rub the dirty oil between your fingers to feel it). This is also the time when, if it will break, it will break, so you may want it replaced under warranty. After a couple of thousand miles or after the first service at three thousand miles I'd buy the chainring I really wanted and fit it regardless because the chances are that, unless one abuses the box grotesquely, one won't ever require warranty service.

Well, it's been 22 months and one oil change ( another one not far off ) later and I think I'll try swapping from 42x17 to 38x17, as I'd much prefer an 18-95" range than the current 20-105". I simply never use gear 14 on my 29er mtb; not even on the road, going downhill. I climb some pretty steep hills, and while my lowest gear has worked ok, I like the idea of having one in reserve  :)

Of course, it doesn't hurt that I'm now 1kg under that cursed 100kg weight limit of Rohloff's.

For my Iceland trip I ran 36 and 16, that gave me 16.5 to 86.5 gear inch range.  The lowest gear was perfect, I wished I had higher gears a couple times when I spun out going down long shallow hills, but I would not have traded my lowest gear for any higher ones.  Thus, that was the closest to the perfect range that I could have gotten for that trip. 

If I had any gears that were lower, I would not have been able to sustain pedaling fast enough on any tall hills to go fast enough to maintain vertical and directional stability.  That is why I say the lowest gear was perfect, any lower would have been too low for me to use.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: PeteG on March 13, 2018, 11:38:46 AM
I don't believe I'd ever want more than 90" on this bike, so a spread of 17-90" is very appealing ( either 34x16 or 32x15 ), and more ground-to-chainring clearance would also be nice.

Despite those gears still giving me a ratio of about 2.12/3, I guess I'm still cautious, due to my 99kg being so close to that warranty limit. I do wish Rohloff could be more clear, as I wouldn't suddenly generate tandem-level amounts of torque, simply by gaining 2kg :)
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: mickeg on March 13, 2018, 06:10:00 PM
I don't believe I'd ever want more than 90" on this bike, so a spread of 17-90" is very appealing ( either 34x16 or 32x15 ), and more ground-to-chainring clearance would also be nice.
...

What kind of crankset would you use that has a 32?  A 34 is pretty easy to set up on a five arm 110 mm BCD crank, but I don't know what kind of crank would work with a 32?

I run chainrings and sprockets that have even numbers of teeth.  I cut a small notch in one tooth on each and I always put my chains on so that a link with outer plates is on that notched tooth.
https://www.sheldonbrown.com/chain-life.html

After a while, dirt fills in the notch, I later used a bit of nail polish to mark that tooth too so it is easier to find.
Title: Re: What's your Rohloff combo (chainring, cog)?
Post by: PeteG on March 13, 2018, 06:51:16 PM

What kind of crankset would you use that has a 32?  A 34 is pretty easy to set up on a five arm 110 mm BCD crank, but I don't know what kind of crank would work with a 32?


It's a 4 arm 104bcd crankset.