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Gearing difference between 650c and 700c...(8 posts)

Gearing difference between 650c and 700c...enclavecat
Sep 27, 2002 5:18 PM
I am pretty sure that you have to run a larger gear to achieve the same speed on a bike with 650's vs. 700's, but how much larger do you need to go?
Info....coonass
Sep 27, 2002 5:41 PM
http://www.analyticcycling.com/GearSelection_Page.html
simpler answer...C-40
Sep 27, 2002 6:00 PM
Typically you would use an 11-21 instead of a 12-23 to get the closest possible gearing to a 700c setup. In other words, reduce the smallest cog by one tooth and reduce the largest cog by two teeth. That's as close as you'll get with standard cassettes.
simpler answer...enclavecat
Sep 27, 2002 6:51 PM
Merci...
re: Gearing difference between 650c and 700c...Lactate Junkie
Sep 28, 2002 9:30 AM
IMHO--Better than playing with the cassette--add 2-3 teeth on the front chain rings. A 55 or 56 by 42 will give you almost the same ratios as a 53/39 with the same cogs in the back.
not enough change...C-40
Sep 29, 2002 4:55 AM
The problem with this idea is that the increase in gear ratio by adding 3 teeth to the big ring is only about 5%. An increase of 8-10% is needed to make up the entire difference.

Changing chain rings would be the only option if you wanted to get the equivalent ratio of a 53/11 top gear with 650c wheels.
not enough change...Lactate Junkie
Sep 29, 2002 2:23 PM
It actually works fine. The 56 gives you a gear inch difference of less than 2” for any given cog in the back vs a 53 and the 42 gives you less than 1” variation against a 39. The advantage of changing the rings rather than the cogs is it gives you the ability to use whatever cluster you need to in the back. I regularly change from an11-21 to 12-23 to 11-23 or a 12-25 depending on where I am riding. If I left the 53 up front, when I would not have the equivalent of a 53-11 at times when I need it, although I would have something lower than a 39/25 when I need that.
not enough change...Lactate Junkie
Sep 30, 2002 10:12 AM
Don't know what happened, that is a 2 inch variation for a 56 and a 1 inch variation for 42 vs. a 53 and 39