I've just bought some new 105 10 speed STI shifters for my roadbike. I have an 8 speed cassette on two year old 105 wheels. Will my shifters work ok (with alternate rear mech cable routing?) or will I have to buy a 10 spd cassette and new chain? If so, will this cause me probs as I have an old Campag chainset - will the chainwheel teeth be too wide/incompatible?
I have heard stories of using the alternate cable routing when you have a 1 gear difference, but I doubt it with 8 to 10. Slap on a 10 speed cassette and you should be OK with the new brifters. You might have to fiddle with the FD some to fine tune it. Also, you'll need a 10 speed chain since they are thinner to accomodate the closer spacing of the rear cluster.