135mm rear spacing with road crankset? I am about to upgrade my CX bike from the old 105-5700 (10spd) to Rival 22 (11spd). I have all the parts already and while reading the crankset/BB (GXP) manual I noticed the following:

Use the provided spacers with wide axle cranksets on 135 mm OLD rear triangle frames.


My frame does have 135mm OLD (and 68mm english bottom bracket).

As far as I understand, the Rival crankset is a road component designed for the standard 130mm road bike rear spacing and 68mm BB but in my case the bike has 135mm spacing.

How does this affect me? Can I use the spacers with my 68mm bracket (GXP has two 2.5mm spacers but I assume they won't fit because they are for 73mm BB AND/OR the crankset won't accomodate them)? Should I even worry about this (it's just 2.5mm on one side and the chain is flexible anyways)?
They make versions of their cranks, mostly sold through OEMs, with spindle lengths optimized for the chainline of a 135 rear end. You'll probably be fine, but may run into problems outlined starting on page 44 of this document. Chainstay length plays a big role in the likelihood of issues. The crank you have, if it's the normal Rival 22 crank, will not give you any choices for what front chainline it gives you, since it can't accomodate spacers under the cups.