As note that Di2, at least in the recent software, may lock out certain gear combo’s, so crank and cassette dependent, you may not be able to shift the system to all 22 gears. You sometimes have to cheat the system somewhat and tell it you are using a 53/39 crank and 12-25 cassette (regardless of what you have), then set to manual mode and Gear Position to Not Set, in order to get the rear derailer to the 2 smallest cogs.

I discovered this in January while setting up a 50/34 crank and 11-23 (11 spd.) cassette, that I could not access the 12 or 11 cog, even in manual mode or Gear Position Off, while in the 34 small ring. Issue 1 was Shimano has discontinued the 11-23, so it doesn’t even show up in the E-Tube settings as a cassette to use.

Note that this may be a moot point if desiring to use Synchro, as the gear chart in E-Tube shows, you have other ring/cog choices to get the same gear inches you would find in the 34/12 and once you figure out where the shift points are, it shifts the system for you when you need the next available gear.

And cheating the system by indicating a crank/cassettes that you are not using only rears it’s head if viewing the gear positions on a Garmin head unit or some such, otherwise the system doesn’t care what you actually have in use, as long as you configure chain length correctly.

I have my system set to Full Synchro and so far am happy with it. I switched to a 14-28 cassette, live in the big ring most of the time, have no need for a 50/11 anyway, so am pleased with how it all works. I like having the Gear Position on the Garmin 1000, means I don’t have to look back at the cassette to see what gear I’m in.

I have noted though, that using BT on the Di2 battery in a constant link to the Garmin while riding, does use up DN110 battery life, when it went from 100% to 90% in about 5 riding hrs. (As displayed on the Garmin) Not linking BT to the Garmin showed no add’l battery drain over the next 5 hrs.