I want to have the ability to change chainsets depending on terrain. I currently have the compact Ultegra 6750 chainset and am after a 6700 53/39 for the flats and races etc. Are the axels the same diameter and width? I have an S-works 2011 tarmac. Not sure what the BB is, I think it's a press fit BB30 but I could be wrong.
Any advice would be greatly appreciated. Thanks in advance.