Originally Posted by
dstrong
Number of gears for shifters and cassette must match. In other words, you can't put a 9 speed cassette on if you have 10-speed shifters. The indexing will be off.
The front will be fine with the change from standard to compact double. Why not just buy 11-23 and 12-27 10-speed cassettes (other than they're expensive!). If you have the two cassettes, it's likely you'll need two chains...although your current chain will probably work for one of the set ups...probably the 12-27...but you'll need a shorter chain for the 11-23 setup. The derailluers are fine.
Than you for your input. I was thinking of going to the 9sp. because I don't need all the options of the 10sp. Some of the shifts in the middle of the 10sp. cassette don't seem all that different.