% difference between gears ahhhhhh!!!!
01-04-14 | 01:59 PM
#1
Thread Starter
Senior Member
Joined: Aug 2010
Posts: 91
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From: East Coast, Canada
% difference between gears ahhhhhh!!!!
This is driving me insane.
Sheldon Brown's gear charts say that the difference between 53/11 (128.9") and 53/12 (118.2") is 9.1%.
How does he get that answer?
Math incompetent,
G
Sheldon Brown's gear charts say that the difference between 53/11 (128.9") and 53/12 (118.2") is 9.1%.
How does he get that answer?
Math incompetent,
G
01-04-14 | 03:23 PM
#4
Senior Member
Joined: Apr 2011
Posts: 15,278
Likes: 342
From: Alpharetta, GA
Bikes: Nashbar Road
Converting to gear inches is what confuses things. It's just extraneous when comparing gears, where gear ratios are all that's needed.
(52/11 -52/12) = (52/11)/(52/12) - 1 = (12/11) - 1 = 1.0909 - 1 = .091 = 9.1%
52/12
When you think about it, only the rear cogs matter for the percentage increase when all else is the same so you can write it down at the start:
(12-11)/11 = 1/11 = .091
(52/11 -52/12) = (52/11)/(52/12) - 1 = (12/11) - 1 = 1.0909 - 1 = .091 = 9.1%
52/12
When you think about it, only the rear cogs matter for the percentage increase when all else is the same so you can write it down at the start:
(12-11)/11 = 1/11 = .091
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