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Old 10-26-08, 01:52 PM   #1
ogbigbird
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gear inches

i was trying to remember the formula for figuring out "gear inches". i remember it's something like chainring multiplied by wheel or cog size, divided by something else. if someone could give me the formula to figure this out, that would be swell.

pt2 of my question, is that not only do i have bikes with conventional 26x1.75/2.125 wheels, but also a few 26x1 3/8. since these are two different wheel sizes in reality, what numbers do i plug in for the 26x1 3/8 wheel vs the conv 26' wheel. and what exactly is "gear inchs"? i used to know this formula, but that was a long time ago. thanks
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Old 10-26-08, 01:55 PM   #2
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5 seconds of googling:

http://en.wikipedia.org/wiki/Gear_inches
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Old 10-26-08, 02:17 PM   #3
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.01 seconds of memory: (Chainring teeth/cog teeth) x wheel size in inches (eg. 27 or 26 or whatever)

39/13 x 27 = 81 inches
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Old 10-26-08, 02:29 PM   #4
ogbigbird
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thanks! took it a step further and used sheldon's gear calculator.
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Old 10-26-08, 04:03 PM   #5
wmodavis
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http://sheldonbrown.com/gloss_g.html#gearinch
http://sheldonbrown.com/tire-sizing.html

+1 galoot
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