Currently my bike is running Ultegra 6700/with a compact 6750 crank. [same]
With the compact I am running a 11-23 and though I like it I prefer mashing to spinning.
If I buy a 6600 ultegra crank SLC 53/39 the light grey and run a new shimano chain and keep everything else as is, front der. and the full drive train except the crank will their be any problems with compatability and shifting.
Thanks in advance