Dulwich Hill Bicycle Club

If I want to put compact cranks onto the Ultegra Di2 for the Alpine Classic Extreme, do I have to get a whole new crankset or can I just change the chain rings? Does it matter that it's Di2 (other than I have to retune it)? It's a 6700.

Or could I just swap it off my other road bike which is also Ultegra 6700 and has compacts?

You should be able to just swap the crankset over from the other bike, with possibly a slight adjustment to the front derailleur.

CT chainrings runs a different spacing for its bolts, so you'll need a CT specific crankset. Don't forget the chain length may need adjustment too.

Shimano 6700 compacts are 110mm bolt hole centre diameter, the 53-39 is 130mm.

Have to change over the crankset

The new 11 sp Dura-Ace 9000 series cranks are 110 BCD regardless of the chain rings

Thanks for that advice - very helpful!