Originally Posted by
Leinster
Campy do a 12-29. Everybody seems to do a 12-25, which seems odd to me, as anyone who can do all the climbing they want to do in a 25, probably wants an 11, whereas somebody who rides 105 and feels they need a 32 at the back would probably not get much use out of an 11 (except maybe going back down the hill they just came up on the 32).
I have a 12-27 10sp, and would gladly sacrifice my 13t for an 18t (and sometimes for a 30).
I believe you can mix and match up past the largest 3 gears. I've installed and changed my cassettes out a few times and I try to keep them all fairly spaced out because of this.