Gear size

Gary Sinclair

Hi can anyone help me with this? I'm trying to work out the difference between 39x27 to a compact with a 25 on it.

johnny25

This may help - http://www.bikecalc.com/gear_ratios

earthvspace4XTuUWcX

Or this, gives you the gear in inches, need to scroll down the page
http://www.bikecult.com/works/wheelsizes.html

964cup

39 / 27 = 1.444
34 / 25 = 1.36
1.44 - 1.36 = .084
.084 / 1.444 = .058

So 34/25 is about 6% lower than 39/27.

on-yer-bike

Gary: 39 – 29 is the closest to a 34 – 25.