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bmx gearing

dan wask

Turbo Monkey
May 11, 2006
1,463
0
B-More Maryland
I'm pretty clueless as far as gearing goes on bmx bikes. Whats the typical gear combination for something with a 9 tooth driver? I'm looking for a gear combo that compares to something like a 32-16 on a mountainbike.
 

t1maglio

Monkey
Oct 29, 2001
855
0
southern wisconsin
Bmx gearing is like this 1 in front is equal to 2.5 in the back. Originally for general riding everyone ran 44x16. Then things went down to 36x13, now its pretty common to have 25x9.
 

ebrider510

Monkey
Dec 7, 2006
410
0
Bay Area, CA
good common gearing for BMX bike are combos like 30:11, 28:10, 25:9 etc..i run 30:10 and like it. wouldn't mind trying 28:10. on my 26er i run 27:12 which to some people seems high somehow, but to me if seems a little too low at times..
 

cmc

Turbo Monkey
Nov 17, 2006
2,059
5
austin
It's real easy math:

Divide front sprocket by rear sprocket and multiply times wheel size. That gives you the number to compare against.

44/16 X 20 = 55
34/16 X 26 = 55.25
25/9 X 20 = 55.5

I'm surprised you're running 32/16 on a 26". That would be way too spinny for me. It only comes out to 52.
 

MC peepants

Monkey
Sep 20, 2006
143
0
keep in mind of where the rake tabs if your going to be using brakes, i run 25/9 on my frame and the chain rubs. It did say it would accomodate that gearing but maybe only with a newer evo or fly brake. Currently im running the older evo version on a fly mosca frame.