Originally Posted by
Koyote
This is interesting to me, since 11sp Di2 does not shift well in Synchro and Semi-Synchro modes, in my opinion. On my bike, in those modes, the bike seems like it first shifts the FD, then after a very brief lag it will shift the RD. It sort of upsets my cadence twice, rather than smoothing it out.
Exactly this. I still use full syncro on my 11-speed Di2 bikes, but I pay close attention to the shift points because it always seems to happen right when I don't want it to happen. It's worse when down shifting than up shifting in my experience...but it is barely noticeable on the 12-speed.