Question for Rohloff Users
 

Hi all,
Having recently upgraded to pretty much my dream bike (Surly Troll, SONDelux, Rohloff, ETC) I have a question about primary gear ratio. Currently I have a 38 tooth chain ring and a 16 tooth Rohloff gear. That is the "recommended" ratio by Rohloff according to the manual. However, in daily riding I find myself mostly in the top 5-6 gears, only dropping below 8 or 9 for the obvious hill climb. I voiced my complaints to Rohloff directly in Germany. They said that is normal but for my use and body build (close to 100Kg) they recommended me a 15 tooth gear. I have ordered it already and was wondering if anyone else has had experience with over 100kg rider weight ratio of 2.5 instead of the normal 2.35

What are your thoughts?

Shawn

Dont understand the issue .. have 2 hubs, both have 16t cogs. [QBP in USA only stocks that one for spares]

My '04 Koga WTR (26" wheel) came with a 130-39t crank .. replaced it with a M730 ; 110-38t..

other one is in a 20" wheel has a 53t chainring .. Bike Friday Pocket Llama. range pretty much the same..

moved from a hilly location, further down the hill, so not using the whole range , as before, in my commute.

AnyHow,
Quoting the Manual : To prevent overstraining the hub, a minimum sprocket ratio of 2.35 must be used.
15:36 16:38 17:40 anything bigger for a chainring is Fine..

I have a Thorn Raven Nomad with a Rohloff 16 tooth rear 39 front on a 175 crank.
The gearing seems low to me, but the bike is heavy and designed for heavy duty touring.

Sheldon Brown has a gear calculator here.
You can figure out how the various gears on your Rohloff compare to derailleur geared systems.

Rohloff does not recommend a specific gear ratio, they specify a ratio as a minimum so that you do not put too much stress on the internal components.
http://www.rohloff.de/en/news/news_r..._ak/index.html

Look at it this way, the Rohloff gives you very even spacing of the gears from 1st up to 14th gear. Thus, the best way to decide what ratio of chainring to rear cog you need is to figure out if you want a gear higher than your existing 14th gear - - or lower than your existing 1st gear. If gear 14 is too low, you need a bigger chainring or smaller rear cog. Alternatively if your gear 1 is too high, you need a smaller chainring or bigger rear cog. If you never need a higher or lower gear than you have, then life is good and no changes are warranted.

But, stay within their specified ratio. I do not know if it would void the warranty or not, but why risk it?

In flat areas, I spend a lot of time in gears 10 and 11. Probably less than 5 percent of the distance I travel is in gears 1 thru 7.

I am running a 44t chainring with 16t cog. When I tour in hilly areas with a full load of camping gear, I bought a 36t chainring to use instead. When I have a heavy load on the bike, I will need the lower gear and will be going down the hills slower (for safety) so I will not need the higher gears that I otherwise would want to have.

1~7 is a double reduction gear , 8~10 is a single reduction gear. as it is a 7 speed (3_3 speeds -2 common middle gears)
used twice ..

the Hub cog is a 3/32" thick .. so any 8 speed derailleur chain will work and you can run a bigger second chainring ,
just need the chain tensioner to take up the difference.

Ah " so 2.1 not 2.0 .. warrantee toast there .. buffer margin, 0.25.. is then 0.0


29F 24R wheel bike perhaps? (Ibis used to make a 26/24 wheel Mountain -Trials frame)

Oh that is what he was getting at. Thanks for clarifying.

Ie 15:37.5 16:40 17:42.5

Ok, Rohloff didn't go into that much detail on the phone. Only suggested I go down one tooth in the rear. They only offer a 13t 15t 16t and a 17t. They said 13 would lose lots of climbing ability and would also require adjustment to chain line. 15t would be a direct swap. Chainring changes in my situation would be expensive past 38t because I currently have a 104bcd crank and not too many 40t rings out there for that size. It never occurred to me that 2.35 was the minimum and anything higher was still allowed. Thanks for the explanations
Shawn

Here is a 44 tooth chainring with 104 bcd. You'll get better wearing on the parts to go larger in front.

http://harriscyclery.net/product/dim...r1915-qc49.htm

You already have the 15 tooth sprocket on order so start there.

I ride with the old minimum of 38x16 and find myself in 1 all the time. Here was today's ride:

http://www.mapmyride.com/us/woodstoc...route-51584600

but probably it's just being 57 old and not athletic in the least! But hey I get out and ride anyway!

I have a double crankset, run a bashguard/chainguard in the outer position, the chainring in the inner position.

The plan is if I go somewhere with massive hill climbing, install both the 36t and 44t onto the crank (with no bashguard) before I leave home. No tensioner. If I am going to be climbing substantial hills for hours, then in preparation the evening before, remove a section of chain and move the chain over to the 36t from the 44t, readjust the eccentric. Have two quick links installed on the chain to make this an easy change. I do not want a tensioner or front derailleur, the less hardware and fewer things that can go wrong, the better.

I picked 44t chainring for normal around-home use, that puts my gearing in about the same range of gearing that I have on my derailleur touring bikes. I use gear 1 and gear 14 with about the same frequency, so that appears to be just about right.

For sizing the smaller chainring, I figured out what my slowest speed was that I could stay upright. I then calculated what chainring I would need to give me that speed with a cadence of about 72, which is the lowest cadence that I like to run. The result is a 36t chainring with 16t rear cog. I tried this combination, it allowed me to climb at a very low speed with comfortable cadence, but I really missed the higher gears, thus the 36t chainring would be used only for those days with a lot of climbing when I need the lowest possible gearing.

Chainline is not perfect, the chainline would be just right if I put the chainring in the outer position. But, it is close enough and I am not going to obsess over it. I intentionally chose a shorter spindle than would have been ideal for chainline because I wanted the Q factor on my Rohloff bike to be similar to my other bikes.

Anyhow..
90" high in 14th, seems sufficient in my experience.. which is what a 61~2" 11th (the direct gear) gives..
[the 38:16x26, & 53:16x20 are both in that range]

I just leave it as is.. only have a chain tensioner on the biFri because, since the rear folds,
and the hinge is behind the BB, there is some slack to deal with..

both are doubles but, just 1, toothed, chainring.. the 38t is Stainless Steel by Surly..

I am running 40-16 on my Ogre. I tried 44-16, 42-16, and 38-16 before I settled on this. This puts me in gear 9-10 for most of my relatively level-ground riding which is where I am convinced it ought to be. I believe that your normal-flat running get should be 75% of the top. You always need smaller ones for wind/hills. While you also need taller gears for wind-at-your back and down hills, you spend more time going up. The Troll has smaller wheels, so smaller gears are probably in order.

Inverse ... same external gear ratio, smaller wheels the gear inch (as if a big penny farthing bike wheel) is lower .

hence a use of a 16:53 with a 20" wheel.



a 29er wheel needs a lower ratio because the wheel diameter is bigger .

the hub manufacturers decision was to allow a 2.1:1 for 29ers , followed that need .


Of course us old people are not really the ones straining the mechanicals.

You are correct, I miss-stated what I intended to say...taller gears...smaller cog.

Thorn has regularly supplied their touring bikes in an "illegal" ratio. It isn't anything to worry about. Rohloff may have some worries about what a 275 monster off road racer would do to their gear, but Mr. Twiddles on a touring bike is no threat to the health of the hub. I don't really care what the guarantee says since the correct ratios are more important to me than some hypothetical situation of making a return.

http://www.sjscycles.com/pdfFiles/Li...RohloffWeb.pdf

In my browser, the relevant sections are next to the heading "Further developments".

My Ogre runs 622 rims (700c) and I use 34T chain-ring and a 16T sprocket on the hub.
This offers approx 17.3 to 90 gear inches.
I'd prefer a little lower but I'm at the minimum to keep within warranty already so will just have to harden up.
I've been not riding for a while and am unfit so struggling a little on the hill work even with the 17.3 gear inches.
I'm yet to use top gear but have spent a lot of time in bottom.
I think the Rohloff is a bit of a pig being heavy and uncrisp in gear changing especially compared to my other bikes Sram Dualdrive.
However I have little interest in derailleur maintenance and it is for this reason I appreciate my "Hoff" most.
As a utilitarian piece of equipment I value it highly.

Are you 100 kg + and in good shape or carrying a bit of a "energy reserve" on the belly :) And how much does your bike/gear weigh?

I use my Troll (26" wheels x 2" tires) with a 42-16 ratio with 175 mm crank arms. I am 158 lbs, max 75 lbs bike/gear weight and in decent shape.

Touring, I find generally I run out of gears on the top end while on flat ground cruising, but like having the low gearing for the hills. Off tour, I run out of gears in about 3 seconds. Not suitable at all. When my sprockets wear out in about another 5000 km or so, I'm going to use a 44 or 46 instead, along with about 10 lbs less gear.

Schlumpf Speed Drive cranks take what ever chain-ring you have, and via planetary overdrive
make it 1.6X larger .. (ex:38/60.8't')

so in effect its like a double chainring set, but no FD and instant gear switching.

I do something similar to this, but I don't run a double crank. I have my commuter chainring, 44T I think, and a touring chainring, 38T. I just swap out the chainring to the desired one as needed, and remove/add links. It takes about 20 minutes.

I forget the numbers off hand, but I think it puts my top gear around 110 gear inches for commuting, and when swapped - my touring granny around 17 gear inches. Touring top gear doesn't matter as I wouldn't be in in for long anyway:)