Was wondering if a 9 speed Shimano Tiagra 4550 double chainset will be compatible with a 10 speed chain and 10 speed shifter? I know the rings may be a little thicker and wider spaced, but am wondering if that will stop them working.
Been there, done that. No problem. I don't know if the rings are really any different. The whole 9/10 speed is a Shimano thing anyway. You don't see rings or cranks designated 9 or 10 from folks like FSA.