Originally Posted by
dksix
I ordered a 12-32 cassette but haven't decided on what RD I will use yet. I have an extra 8 speed MTB RD that I planned to try when the cassette comes in. I have 5700 on it now, thought about buying one of the RoadLink extensions and continue using the one I have now instead of buying a 5700-GS or one of the MTB 9 speed people are often using.
If you're running a compact crankset, there's a good chance your existing 5700 rear derailleur would work with a 32t cassette, it would pretty easy to check out. You need to have enough chain length to run the big/big combo.