Old ultegra di2 issue

Hi there! Trying to resolve an issue I’m having on my road bike equipped with 6770 ultegra di2. I believe this is the first variation of ultegra di2. So what’s happening is I’m in the big ring up front, I’m climbing a grade, i shift into bigger/easier cogs as the climb continues. Eventually I get to the biggest cog and the chain drops to the small chainring up front. It’s not intentional and it really catches me off guard as I’m not expecting it. It only happens at slower speeds and is a minor inconvenience but it’s starting to annoy me. As soon as I shift into a smaller cog or two the front will jump back on the big chainring.
I know cross chaining isn’t ideal but I feel with a 2x setup it should be achievable. Is this just a matter of adjusting the FD to hold the chain on in this gear combo? even if it creates some chain rub on the FD it could serve as a reminder you chain gears.
My new road bike is about 8 weeks out and I feel guilty selling my old bike without it functioning 100% properly.

There’s this set of directions for the FD on page 39. I had 6770 in the past and never had the same problem when cross chaining.

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sounds like synchro shift is turned on

Something worth looking at - I’ve had issues with front chain ring wear on my 6770 group set which manifested itself in unwanted front shifts. After an entire lifetime of never having to replace a front chain ring, on this bike on on my 3rd set in 6 years.

I agree. But I don’t think synchroshift is even an option for 6770. I may be wrong on that though.

I could definitely see that happening, but I just replaced the chainrings, cassette, and chain in the fall. Most of my rides since then have been on the trainer except one outdoor ride a week. That chain is still not at .50 wear, I just checked it a week ago.

A quick (and I mean QUICK…only looked at one link) google search seems to confirm this…which to me idicates it is a question of tweaking your FD settings / adjustments.

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If you don’t have one yet, its worth the $5-$10 to get a feeler gauge set so you aren’t just eyeballing the gap specs in the set up instructions.


Probably a very useful tool in this scenario. I’m going to see if I can find one, if not then buy one.