Rohloff permitted sprocket ratios revised

Rohloff permitted sprocket ratios revised

Postby rifraf » Mon Dec 24, 2012 1:24 am

Not sure if this has come up before but I know I've read previously here about concerns with final drive ratio.
For those amongst us (like me who only spotted it this evening) Rohloff has revised the permitted transmission factor to 2.1 down from 2.38 with the caveat that its targeted only for solo cyclists under 100kg.

The spiel:
News
SPEEDHUB 500/14 revised permitted transmission factor now 2.1!
11.12.2012

The permitted sprocket ratios for the SPEEDHUB 500/14 were set to ensure the hub would not be damaged due to a high input torque. These limits were set identical to the lower limits of derailleur systems of the day (2.35) but these obviously also contained a small buffer.

Current derailleur systems offer lower gear ratios now which are particularly favored by 29er cyclists for hard off-road climbs. Due to the increased interest in these bicycles the Rohloff AG has reviewed our permitted ratios and reduced the transmission factor further to just 2.1 for solo cyclists under 100kg. The 'buffer' that the SPEEDHUB previously had available is not longer present and this new factor must not be reduced further.

SPEEDHUB equipped bicycles may now achieve 1.36m per crank revolution in their lowest gear without risk of losing warranty cover.

Calculating the Transmission factor:

36 tooth front chainring with a 17 tooth rear sprocket = 36:17= factor 2.11 (updated Table can be found in the Owners Manual, page 20).


The Transmission factor of 2.5 still applies for Tandem use and cyclists weighing over 100kg!

http://www.rohloff.de/en/news/news_rss/ ... index.html

There, my work is done - dont say I didnt give you anything for xmas :D
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by BNA » Mon Dec 24, 2012 3:15 pm

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Re: Rohloff permitted sprocket ratios revised

Postby RonK » Mon Dec 24, 2012 3:15 pm

Hehe, so when Rohloff realised that their warranty exclusion was in fact excluding Rohloff sales to the growth market segment, they just changed their own rule. Now that's what I call self-serving.

And isn't the weight limit a joke - what are they going to do, weigh riders who make a warranty claim?

For that matter, who is going to present their bike for a warranty claim with an oversized sprocket?
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Re: Rohloff permitted sprocket ratios revised

Postby rifraf » Mon Dec 24, 2012 3:23 pm

RonK wrote:Hehe, so when Rohloff realised that their warranty exclusion was in fact excluding Rohloff sales to the growth market segment, they just changed their own rule. Now that's what I call self-serving.

Certainly with a 29er build with loaded touring focus the Rohloff purchase was bringing up questions of satisfactory gearing. At least it was for me. I started looking once again at 26" wheel bike options. This will help throw a "little" oil on troubled waters. Of course the warranty wont cover touring loads me thinks as they only mention rider weights. :roll:
Warranty returns will be sprocketless and with a cheesy grin! :idea:
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Re: Rohloff permitted sprocket ratios revised

Postby RonK » Mon Dec 24, 2012 3:39 pm

rifraf wrote:Of course the warranty wont cover touring loads me thinks as they only mention rider weights.


It's not the amount of load on the bike, but that the heavier rider generates more torque.
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Re: Rohloff permitted sprocket ratios revised

Postby rifraf » Mon Dec 24, 2012 3:56 pm

RonK wrote:
rifraf wrote:Of course the warranty wont cover touring loads me thinks as they only mention rider weights.


It's not the amount of load on the bike, but that the heavier rider generates more torque.

I find women, who hopefully tend on average to be lighter, generate loads more talk :wink:

Best we dont mention their luggage requirements :shock:
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Re: Rohloff permitted sprocket ratios revised

Postby exadios » Mon Dec 24, 2012 10:25 pm

My minimum ratio is currently 24/13 = 1.85. I've had no problems with this set up but then I'm not a candidate for the Tour de France either (maybe later when the performance enhancing drugs kick in :) ). I use 152 mm cranks so a more representative ratio would be (24*170)/(13*152) = 2.06.
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Re: Rohloff permitted sprocket ratios revised

Postby rifraf » Thu Feb 07, 2013 1:11 pm

exadios wrote:My minimum ratio is currently 24/13 = 1.85. I've had no problems with this set up but then I'm not a candidate for the Tour de France either (maybe later when the performance enhancing drugs kick in :) ). I use 152 mm cranks so a more representative ratio would be (24*170)/(13*152) = 2.06.


Wow, I've not seen 152mm cranks. Sound like they'd be good for spinning. Seems much easier to find longer cranks.
I was probably not looking in the right places but after wishing for something in and around the 165mm range, I got sick of looking and grabbed the next set of
square tapered 170's that came along.
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Re: Rohloff permitted sprocket ratios revised

Postby exadios » Thu Feb 07, 2013 9:12 pm

rifraf wrote:
exadios wrote:My minimum ratio is currently 24/13 = 1.85. I've had no problems with this set up but then I'm not a candidate for the Tour de France either (maybe later when the performance enhancing drugs kick in :) ). I use 152 mm cranks so a more representative ratio would be (24*170)/(13*152) = 2.06.


Wow, I've not seen 152mm cranks. Sound like they'd be good for spinning. Seems much easier to find longer cranks.
I was probably not looking in the right places but after wishing for something in and around the 165mm range, I got sick of looking and grabbed the next set of
square tapered 170's that came along.


Most recumbent riders use short cranks - some shorter than mine. I got mine from Greenspeed. If you want short cranks you need to look on line. You will not find them at your LBS.
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Re: Rohloff permitted sprocket ratios revised

Postby rifraf » Thu Feb 07, 2013 11:16 pm

exadios wrote:
Most recumbent riders use short cranks - some shorter than mine. I got mine from Greenspeed. If you want short cranks you need to look on line. You will not find them at your LBS.

Thanks for the heads up :D
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