Author Topic: What's your Rohloff combo (chainring, cog)?  (Read 116134 times)

mickeg

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Re: What's your Rohloff combo (chainring, cog)?
« Reply #210 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.

Hoodatder

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Re: What's your Rohloff combo (chainring, cog)?
« Reply #211 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

Hoodatder

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Re: What's your Rohloff combo (chainring, cog)?
« Reply #212 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

Danneaux

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Re: What's your Rohloff combo (chainring, cog)?
« Reply #213 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)
« Last Edit: January 02, 2016, 09:04:02 PM by Danneaux »

mickeg

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Re: What's your Rohloff combo (chainring, cog)?
« Reply #214 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.

Hoodatder

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Re: What's your Rohloff combo (chainring, cog)?
« Reply #215 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


Hoodatder

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Re: What's your Rohloff combo (chainring, cog)?
« Reply #216 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
« Last Edit: January 02, 2016, 11:12:37 PM by hoodatder »

Danneaux

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Re: What's your Rohloff combo (chainring, cog)?
« Reply #217 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.

mickeg

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Re: What's your Rohloff combo (chainring, cog)?
« Reply #218 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.

John Saxby

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Re: What's your Rohloff combo (chainring, cog)?
« Reply #219 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

Hoodatder

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Re: What's your Rohloff combo (chainring, cog)?
« Reply #220 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
« Last Edit: January 03, 2016, 11:42:39 PM by hoodatder »

mickeg

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Re: What's your Rohloff combo (chainring, cog)?
« Reply #221 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.

John Saxby

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Re: What's your Rohloff combo (chainring, cog)?
« Reply #222 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

geocycle

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Re: What's your Rohloff combo (chainring, cog)?
« Reply #223 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.
« Last Edit: January 04, 2016, 05:53:07 PM by geocycle »
 

Hoodatder

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Re: What's your Rohloff combo (chainring, cog)?
« Reply #224 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