Di2 front derailleur problem

Has anyone ever seen a problem with a front di2 derailleur (Ultegra FD-R8050) where the top adjustment bolt seems to change its position in the middle of the ride allowing the derailleur to move farther away from the frame causing the inner plate to rub against the big chain ring when in the big chain ring?

This one:

I assume you are doing the electronic low and top adjustment after doing the mechanical top first, making sure the rear mech is in the correct gear for each adjustment. If you are doing that I have no idea since I’ve never heard of this issue. I set mine up initially and haven’t touched it since.

Yep. Followed https://bettershifting.com/micro-adjust-di2-derailleurs-using-computer-no-levers-required/

(Also been using them for over a year now)

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Could it be that the set screw that holds it against the down tube or the provided metal piece is not fully extended? This gives the derailleur the proper leverage and makes sure it doesn’t move.

It is extended. Also that would cause the opposite problem I would think as it couldn’t be pushed out too far

Well, I have no idea then. Terry from Di2 Center is a member here. Maybe he’ll see this and be able to figure out what is going on. And FWIW, I’m not using the jack screw against the frame on my bike and it shifts better than any bike I’ve ever had including my last bike which had the jack screw engaged.

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Hi :)!

Does this happen in every (RD -> Big Ring) gear? I was wondering whether this is the FD auto trimming depending no the gear you’re in. Either way, even in the middle range of the cassette you should be able to get the FD to its outer most range by pressing the big-button-on-left-shifter twice.

Also, you may have already seen this page, but I thought I’d mention it anyway: https://bettershifting.com/set-up-front-derailleur-limit-screw-adjustment-bolt-one-bolt-derailleurs/
(this information is also in the dealer manual, but personally I find it’s easy to miss a step or two in the dealer manuals).

The next bit is not part of my reply to your issue, but just something on the support bolt.
A Di2 bike can work without, just like TheOtherOne says. (according to Shimano the support bolt not only helps the FD stay in place though, it also protects the frame and it should always be used on carbon frames.)

When I set up my 6870 bike I forgot about the support bolt and have never ‘fixed’ that on that bike. I did experience some dropped chains when shifting to the big ring at first though.

I set the top adjustment bolt based on the small company and big ring and most recently did all the electrical adjustments when plugged into the computer. But I’m not sure that is significant in that the front derailleur rubs the big ring when shifted onto the big ring and in basically all the gears in the back. (Obviously a bit more in the smaller cogs)

It basically went from working perfectly fine (shifting was working great and no sound of rub) with enough steep rolling hills I used all the gears to suddenly the bike making a sound and noticing the derailleur in the wrong position (though still able to shift fine between rings with the small ring being quiet and the big ring being very noisy)

Thanks

Interesting! I’ll try to get back to this tonight - am a bit swamped with work at the moment and I’d have to do some research :}

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I can’t figure out what triggers this problem. (Repro steps) Even if I screwed up adjustment, did something wrong, and missed something cause I didn’t see it. This problem is very obvious from the volume of nose from the rub. The bike was working fine all last year. I did a hilly ride with no problems Saturday. It was perfectly quiet for the first two thirds Sunday and then started making noise. Other then the few times when I accidentally shift the front without pedaling the front doesn’t make that noise for when it tries to move but can’t. Never crashed or had it enter recovery mode (though falling on the non drive side should have no impact and falling on the drive side should have the opposite problem at worst)

The front derailleur has no true high and low setter, right? In the sense that the high and low adjustment in the past were physical blocks that kept things from moving past that point. With this it’s really just adjusting the derailleur to where the high point should be and all the electrical settings tell the motor where to stop. So it’s possible the motor isn’t stopping at the correct location and it’s position calibration is off? Is that a possibility or am I making the wrong assumption?

On these one-bolt FDs you first set the Top limit using the bolt (0.5 - 1mm between chain and chain guide outer plate).

Then the low limit using the shifters: https://bettershifting.com/set-up-front-derailleur-limit-screw-adjustment-bolt-one-bolt-derailleurs/#setthelowlimit

And finally set the ‘electronic top limit’ using the shifters: https://bettershifting.com/set-up-front-derailleur-limit-screw-adjustment-bolt-one-bolt-derailleurs/#setthehightoplimit

I’m not 100% sure, but I think this last setting tells the derailleur what its final position should be, but still allowing it to over-shfit and then move back (because it isn’t physically blocked).

I did all those steps. (Well using the software the adjust most recently, but that goes through all the steps) Though now that I think about it this problem only happened after the software adjustment instead of the old way. (trainer rear cassette it sightly off from my wheel so had to adjust when starting outdoor riding)

Took the bike to a dealer but mostly cause I noticed the cage wasn’t exactly parralel to the chain rings but was very close. Its a braze on connection and I couldn’t get the back of the derailleur in more so figure the braze on might be out of alignment (Its a fuji bike so a fuji dealer in case this is a warranty issue)

Though the way the owner of the shop talked I’m pretty sure he can’t solve the derailleur issue itself as he talked about how they don’t stay in adjustment forever. I’d say staying in adjustment for under 3 months seems like a reasonable expectation. He was also talking metal fatigue while I’m thinking the derailleur is under 2 years old, there shouldn’t be any of consequence.

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FWIW, if something is wrong with the FD - Shimano offer a 2-year warranty on all Di2 components as far as I know.