Thorn Cycles Forum

Community => Rohloff Internal Hub Gears => Topic started by: Jitensha on July 30, 2010, 07:40:43 PM

Title: Gearing
Post by: Jitensha on July 30, 2010, 07:40:43 PM

Hi all,

I've got a 38 tooth chainwheel and a 16 tooth rear sprocket on my Thorn Raven. I find the gearing a bit low - particularly when riding unloaded. I find I'm in gear 13 a lot. I'd like to change my chainwheel/and or sprocket so that my current gear 11 becomes the equivalent of gear 13. I think that would give me a top gear about 30% higher than what I've got at the moment. Does anybody know of a gearing calculator that will help me work out what size chainwheel/sprocket combination I need.

Many thanks

Dave

Title: Re: Gearing
Post by: peddles on July 30, 2010, 08:05:54 PM

This should do it for you... Have fun!
http://www.sheldonbrown.com/gears/internal.html

Title: Re: Gearing
Post by: julk on July 30, 2010, 08:23:44 PM

49x16

I have run this through the figures given in the Rohloff manual and it is an almost exact answer to your request.

Another way of looking at is a 30% bigger chainwheel is 38 + (0.3x38), or 38 + 11.4 = 49 rounded to a whole number of teeth ;D

Title: Re: Gearing
Post by: Joatamon on July 30, 2010, 10:07:53 PM

If you would like to exchange your 38 tooth for a 44 tooth let me know.

Title: Re: Gearing
Post by: Jitensha on July 31, 2010, 01:03:56 PM

Hi all,

Thanks for replies. All very helpful.

Joatamon, I'm going hold on to the 38 tooth chainwheel because I might use it in future for loaded touring.

Dave

Title: Re: Gearing
Post by: Relayer on August 02, 2010, 05:12:56 PM

There is good advice/comparisons of Rohloff gearing on Thorn's "Living With a Rohloff" document, see the last page.

http://www.thorncycles.co.uk/thornpdf/ThornLivingWithARohloff.pdf

Title: Re: Gearing
Post by: spooley on August 06, 2010, 03:50:54 PM

I've recently gone from a 39-16 to a 46-16 (stimulated by a chain-wreck which took out a tooth from my original 39-tooth chainwheel!).

I realised that I was spending too much time near the top of my gears, and often found I'd like something a bit higher to hurtle downhill.

A very successful change, for me ... my regular commute has got a bit faster which I think is due to occasional use of my new #14 on the way.

(It was quite an expensive change, since I changed the nice Thorn alloy chainguard, too!)

Simon.