Synchro Shifting

For those of you that have the capability to, do you use synchro shifting and either semi or full?

The bike i recently bought has the D/A Di2, and i’m considering activating the synchro shift… i don’t want to mess around with the software too much, so was hoping to get feedback from you all first before i make the change.


S1 / Semi for me. It simply saves having to change 1-2 cogs on the rear when going from big->small or small->big on the front… which is what I always do anyway. The defaults are all baked in, just double click the junction box to switch modes. Or do it from your Garmin head unit if you have the ANT/BLE thingy.


It’s worth playing around with over the course of a few weeks so that you can get a feel for the different modes. Your personal preferences, how you ride, and the terrain on which you ride will all impact on how each mode works for you.

I tend to have it set on full synchro. For me this works well. Your mileage may vary. Where I live there are lots of very sudden, very steep climbs, so even with the full synchro I am still actively shifting the front chainring more often than relying on the synchro to shift it, but I like the synchro for how it helps me maintain a more even cadence on the longer drags that undulate rather than suddenly pitch up.

One problem I have though is that after I changed my cassette to an 11-32, the app doesn’t allow me to select my exact gearing combination (52/36, 11-32), therefore the synchro shifts no longer match up quite as well as they did previously).

Play around with it and see what you end up liking.

Full syncro on the TT bike, easy to set up and works great. I’ve not other options as I built the bike with just 1 button on the end of each TT extension. Shift up in to big ring is very quick and almost imperceptible from just shifting the front as it shifts both mechs at the same time. Shift down in to little ring there is a slight delay between front and rear shifting, that you can definitely feel. This is apparently deliberate to ensure it doesn’t ship the chain off.

I had never looked at the app as I don’t have Di2 but I just downloaded it a poked around and I was able to choose 52/36 and 11-32 as my gearing combo with full synchro. I can maybe post some screen shots later if you want. I’ve never actually used it with a bike though so it’s possible there is something I am missing.

Also this was on iOS.

I think it really depends on your personal preference. Play around with all three modes to see what suits you best. You might like one mode for group rides and another for training rides in the hills. Either way it’s easily switched back and forth.

I use synchro shifting almost exclusively. Occasionally I’ll switch over to semi synchro (mostly just to keep familiar with the differences between the two). And sometimes I use the no synchro mode just because I like the old time feel of manual shifting (kind of like when I was younger and there only was manual transnmissions on cars and trucks. I sold my manual shift truck a couple years ago and really miss it. It’s a lot of fun having complete control of shifting)).

I got my first Di2 bike last October for my 70th birthday. I played with all three modes to see what they actually did. I settled on full synchro but had to adjust the shifting pattern for my liking when down shifting the rear deraileur so that the large chainring dropped to the lower chain ring one cog sooner . Using etube project from Shimano allowed me to do this easily from my PC and the Di2 battery charger. I purchased the EW-WU111 unit so that I could make adjustments with my smartphone/tablet easily when on a ride or away from my PC.

Good information can be found at

and alsoShimano E-tube Help Manual.pdf (2.4 MB)

Hope this helps somewhat. Just play around with it. If you make a mistake and get confused it’s easy to do a reset.


For me it depends - I first used Synchro Shifting on 6870 Di2. On the older series (6870 / 9070) the front derailleur somehow limits the flexibility in setting up when it shifts from big to small ring.

What you’re looking for in the image above is the amount of white boxes around the top blue box. Those are the points(/ratios/gears) you can set it to shift from big to small.

It wasn’t until Shimano sent me an R8050 setup to play with that I figured out why my 6870 bike was ‘limited’ in this way. People have confirmed that the same is the case for 9070.
(In case you’re wondering, the middle setup doesn’t list 34T x 11T and 12T as valid gears because these are disabled due to Gear Position Control).

I originally used full synchro… and then moved to semi-synchro… and then learned to live with 6870 full synchro and went back to that.

But yeah… tman1234 - like Shane says, just double click the junction box to switch modes. :wink:

Changing the chainrings / cassette in e-tube doesn’t really do that much - the main things it does are:

  • change whether or not gear position control is active / can be changed
  • change the displayed gear ratios in the synchro shift map (this is just a display/interface thing)

The range of gears that can be seen is limited by the “capability” of the equipment found by etube. So in R8000 if you have a “short” cage RD you can not see or select a cassette with 11-32. (the max size recommended by Shimano is 28). If you fit a “long” cage RD you are then able to see the full range.

If that is in reply to my post - you are 100% correct, but that is not what I said at all :wink: :wink: :wink: