There is no manual mode on di2 12 speed with TT setup. As you say, there's not enough buttons to have manual. I'm 'adapting' to that coming from cabled non electronic shifting. I'm still sorting out the mapping of the shift point in synchro.

Build a 12-speed Di2 Time Trial / Triathlon bike (bettershifting.com)

In Manual Mode I can control all shifts EXCEPT down to the small ring—but fully up/down on the cogs—that’s a SOLID BLUE light when checking mode on the rear derailleur.

Semi-sync mode seems to be the next best thing with 2-blue flashes when checking which mode your in. But per your link above—seems only full SYNCHRO is available is how I read it on a TT bike.

3 blue flashes is full Synchro Mode which I don’t care for.

Thanks for the response. It would be nice to have Shimano update the firmware (if this is possible with mapping maybe) so that if you held down BOTH buttons it would go to the small ring. Haven’t played with the mapping in E-TUBE app yet. Miss the control of WIRED shifting but enjoy the benefits of electronic shifting too.

What you've got is it forced into a manual mode that doesn't allow you to move the FD as yoou've found. So perhaps semantics, but only sync shift will work on 12sp. At least at present. I'm assuming they'll bring out 12sp 2 button shifters at some point, but until then this is what we have.

You can add additional sprint buttons, and then get it to work too.

Thanks for the info!

I doubt it. When they scrapped it on 11 speed I thought it was weird but you just get used to synchro. I even turned it on for my road bike and almost never use the left lever.

However, I just checked and it looks like you “could” set the shifters to do the front derailleur. So you could see the brake levers to be up and down for the front and leave the bar end shifter buttons for the rear cassette. I didn’t dare try that as synchro works just fine for me.

You can actually do this (add a button each side )
The dude of slow twitch sent me everything I need to make this happen , but I’m yet to install it as the synchro works pretty good and u do get used to it after a while
Best tip is to have the di2 talking to your Garmin , then your Garmin will beep to tell u when it’s gunna change the FD on your next shift , so no surprises

I have the 11spd with 2 on the top and one of each side of the bullhorns...

top does up/down RD and the ones on the bullhorns do up/down FD

u can't do that with 12spd? I tho u can configure the buttons anyway u want?

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The entire event (IM) is like "death by 1000 cuts" and the best race is minimizing all those cuts and losing less blood than the other guy. - Dev

https://forum.slowtwitch.com/...012%20speed#p7734035

So I am in the same boat. totally new to this and not entirely comfortable with not being able to go into full manual. Someone in another group I follow said I should be able to change the buttons in Etube to allow two to control front derailleur one up and one down (ie, the ones on the brake levers) and two to control the rear derailleur (ie, the ones on the aero bar extensions). But it sounds from here that it won’t work? Haven’t tried yet, I want to give full synchro a shot. but any thoughts?

I currently have the older 11 spd 2 button Di2 set up and am nervous about "upgrading" to the 12 speed version. I think I would hate the synchro shift set up. I am wondering if I would just be better off keeping my 11 spd 2 button and not upgrading to the 12 spd. I could simply upgrade my cassette to 11x34 and keep my 2 button wondershifting.

I don't get why Shimano would kill the 2 button set up. It makes sense. Or at least do an update and allow us to manually control the FD.

Anyway, I found this video that seemed worth a watch. https://www.youtube.com/watch?v=QluVgGPk9b4

Yeah it's a little funky having it shift on its own after riding SRAM R2C with full manual control for years...but it is what it is. Shimano could've done a better job here with making the manual part of 12 sp rather than the forced Synchro for TT. I'm sure I'll get used to it. I will say the fun of 12 sp coming from 10 sp (never had 11 and skipped right over that generation of technology), is that those 2 extra gears sure make it easier to find a comfortable cadence & gearing where before I had to basically muscle it up hills.

Also, the drops with shifters is just awesome & found myself still reaching to the aero bars (like my R2C's had) to shift---then paused & realized I never had to move my hands at all. Takes a little time...only about 7 rides on the new ride--it'll def be a learning curve for 12 sp Di2.