Author Topic: What's your Rohloff combo (chainring, cog)?  (Read 116139 times)

Andybg

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Re: What's your Rohloff combo (chainring, cog)?
« Reply #150 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

Tigerbiten

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Re: What's your Rohloff combo (chainring, cog)?
« Reply #151 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

Trikenomad

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Re: What's your Rohloff combo (chainring, cog)?
« Reply #152 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.

« Last Edit: May 20, 2013, 09:24:55 AM by Trikenomad »

Trikenomad

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Re: What's your Rohloff combo (chainring, cog)?
« Reply #153 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.
« Last Edit: May 20, 2013, 04:08:59 AM by Trikenomad »

Trikenomad

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Re: What's your Rohloff combo (chainring, cog)?
« Reply #154 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.







« Last Edit: June 29, 2013, 06:35:39 AM by Trikenomad »

Danneaux

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Re: What's your Rohloff combo (chainring, cog)?
« Reply #155 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.

mickeg

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Re: What's your Rohloff combo (chainring, cog)?
« Reply #156 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

Danneaux

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Re: What's your Rohloff combo (chainring, cog)?
« Reply #157 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.

mickeg

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Re: What's your Rohloff combo (chainring, cog)?
« Reply #158 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.  
« Last Edit: June 29, 2013, 11:25:33 PM by mickeg »

Danneaux

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Re: What's your Rohloff combo (chainring, cog)?
« Reply #159 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.

harlond

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Re: What's your Rohloff combo (chainring, cog)?
« Reply #160 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.

JimK

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Re: What's your Rohloff combo (chainring, cog)?
« Reply #161 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!

Andre Jute

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Re: What's your Rohloff combo (chainring, cog)?
« Reply #162 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!

Huernie

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Re: What's your Rohloff combo (chainring, cog)?
« Reply #163 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?

Danneaux

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Re: What's your Rohloff combo (chainring, cog)?
« Reply #164 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)