Join Date: Apr 2009
Location: New Rochelle, NY
Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
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Originally Posted by davidad
I'm a little lost here. The pitch of the gears is the same as the chain, 1/2". So the wheel should move 1/4".
Follow the reasoning in my first post. I could be wrong (it's not like that never happened) but I don't think so.
The chain wraps 1/2 way around so total chain length change is 1/4" per tooth, but that's is split between the upper and lower loops, moving the axle 1/8". Did I miss something?
Looking at it another way, the chainring is roughly circular. Increasing the circumference by 1" (2 teeth) increases the diameter by .318, or the radius by .159" or roughly 5/32". This is a slightly more than 1/8" and I think that's because a chain on chainring doesn't form a circle, but a polygon of X
sides of 1/2".
Either way we're still looking at about 1/8 - 5/32" or so per tooth.
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Last edited by FBinNY; 03-15-11 at 10:26 PM.