Just completed my build. I had a 105 Di2 groupset left over after upgrading my road bike to Ultegra, so I figured I had to do something with it.
The front derailleur mount is misplaced, at least on the size S frame, it sits far too low. I had to switch to a 50/34 setup, even though my original plan was to run 52/36. I also had to file down the mount slightly to get enough clearance for the derailleur movement.
I’m running elitewheels aero grvl wheelset (32mm internal) with a pair of Hutchinson caracal race tlr 45mm