Shimano Ultegra Di2 Seat Tube Adapter $24.95
Adapt your Di2
If you have a Shimano Di2 system and want to run it on a frame that's designed for a clamp-on front derailleur, then you'll need this adapter clamp. It's available to fit 31.8mm or 34.9mm seat tubes. Simply bolt it directly to your Di2 front derailleur braze-on style mount, and you'll be ready to position the whole assembly onto your seat tube.