Gearing post?- Mtbr.com

1. ## Gearing post?

There used to be a really good post on gearing (e.g. the equivalent gear ratios on 26" and 29er bikes, for a given chainring) under SS FAQ's but it seems to have gone.

Anyone know where I can find something similar on the gearing formula (searched but no luck).

2. 32:16 == 32:18

That's all you really need to know ;-)

You can use the gain ratio formula to calculate the equivalent gear for the combinations you're interested in...
Gain Ratios--A New Way to Designate Bicycle Gears

3. So, starting with the gain ratio formula, and assuming that you will use the same crank arm length and the same chainring size (as you stated) on both bikes, then you can write an equivalent expression, do some algebra, and come up with a pretty simple formula to calculate the equivalent cogs:

Cog(29er) = 29/26 x Cog(26er)

or

Cog(26er) = 26/29 x Cog(29er)

Example - the 29er equivalent for a 32:16 26er gear is:
Cog(29er) = 1.115 x 16 = 17.85 (is close to 18)

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