different size FD
 

I'm in the process of buying an SRAM rival FD. I'm also unfamiliar with certain aspects of bike mechanics.
Anyways. Whats the difference between the 31.9mm and the 34.9mm FD? does it really make that big of a difference?

It does if your seat tube diameter is 34.9 and the derailleur clamp band is 31.9mm.

Take a caliper and measure the tube diameter before ordering.

uh oh.. i just bid on a 34.9 mm and my seat tube is 31.9.. is this a problem?

Yup, but better than the other way around. You can shim it smaller, not larger.

hm, well hopefully i'll get outbid on ebay :/

I'd assume a LBS will have the shims. Don't worry about it.

Maybe an auction will come up for the shims.:rolleyes: