Double Chain Ring...yikes

[VeloVT]

Originally posted by Oakleaf:
I might change out the chainrings before replacing the cassette - five teeth in front will make MUCH more difference than two in back.

Does anyone know what's the maximum differential in a compact? Can she do 53/34, or would that result in poor shifting and/or a lot of cross-chaining?


Whether or not you can go down to a super-small inner ring depends on the Bolt Circle Diameter of your crankset.

I believe standard road doubles (53/39) have 130mm BCD's -- if this is the case with your cranks, you are limited to a 38 small ring.

Most compact doubles have a 110mm BCD; if somehow you ended up with a 110 mm BCD, you can go down to like a 33.

Sheldon Brown has a little information about this on his website, and you will get more if you google some combination of "BCD" and "chainrings".