Sorry guys, I thought the question was pretty clear. Looking for guidance/input on converting existing Ultegra drive train to Di2 SHIFTING ONLY. I understand the cranks, brakes and cassette do not need to be changed. Not saying it isn't expensive but you can in fact get the complete kit sans brakes, cranks and cassette for about $2k not $4k. Basically wondering how difficult mechanically it would be to make the swap. Thanks!!!