R8050 FD went waaaay out of adjustment
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  1. #1
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    R8050 FD went waaaay out of adjustment

    Hi, I'm really new to the world of Di2. I've had it on my bike (as an upgrade) for all of 10 days. The LBS did the build for me (on a S-Works SL4 Roubaix).

    The shifting for the first 9 days has been flawless, even surprised how quiet it was when completely abusing x-chaining (Big-Big for example).

    I'm running 52/36 R8000 Ultegra cranks and 11-30 R8000 cassette and chain.

    Yesterday when riding I thought I was getting some chain rub when in 52-15 and it got worse as moving down the block to the 11 although it was a lot louder than any chain rub I'd had before.
    When I got home I realised that the sound was from the inner FD cage plate rubbing on the back side of the 52T ring, it was waaay over shifting and I can't work out why. I haven't touched a thing as far as adjustment goes.
    I needed to turn the "H" screw about 3-4 times to get the FD back to where it should be which just doesn't make sense as to how it could get so far out of adjustment. Is this sort of thing normal? I'm guessing not.

    The only thing that I DID do to the bike the night before was drop my bars down 1 x 5mm spacer and heat the heat shrink tubing around the 2 cables that go into the down tube (the LBS left it un shrunk knowing I was going to drop my bars at some stage) but can't see how either of those actions could effect such a dramatic change in the FD operation.

    I have it all working fine now, but was wondering if it is common issue that the FD goes a bit whack like this?
    Last edited by TmB123; 2 Weeks Ago at 05:07 PM. Reason: changed 53/36 to 52/36

  2. #2
    'brifter' is a lame word.
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    Not common at all. The only thing I can think of is that they didn't set the High limit at all. Weird that it would work fine for a bunch of rides then basically **** itself. Hard to say w/o seeing in person.
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  3. #3
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    That's what I was thinking, strange that it was working so well though, and the shop itself has a very good rep for doing high quality work (they're actually more of a bike mechanics shop, than a bike shop), all seems a bit odd.
    Last edited by TmB123; 2 Weeks Ago at 05:14 PM.

  4. #4
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    I've seen/heard some unusual Di2 overshift stories....if you unplug the battery from the system does the system still do it? Your crankset is still preloaded and torqued correctly, right? Is the FD bracing set-screw actually set?
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  5. #5
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    Quote Originally Posted by Marc View Post
    I've seen/heard some unusual Di2 overshift stories....if you unplug the battery from the system does the system still do it? Your crankset is still preloaded and torqued correctly, right? Is the FD bracing set-screw actually set?
    I didn't unplug the battery, but have made physical adjustments to remedy the problem so hard to do some testing now. I might unplug the battery on the weekend to see if it messes up the current settings.

    The crankset is the first thing I thought of as I didn't set it up. Was half expecting to see it floating laterally in the BB, but no, tight as can be.

    I didn't check the bracing screw, however the FD didn't have any problem shifting and it seemed to be shifting straight out parallel to the chain rings, it's problem was it was shifting too much!

  6. #6
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    Quote Originally Posted by TmB123 View Post
    I didn't unplug the battery, but have made physical adjustments to remedy the problem so hard to do some testing now. I might unplug the battery on the weekend to see if it messes up the current settings.

    The crankset is the first thing I thought of as I didn't set it up. Was half expecting to see it floating laterally in the BB, but no, tight as can be.

    I didn't check the bracing screw, however the FD didn't have any problem shifting and it seemed to be shifting straight out parallel to the chain rings, it's problem was it was shifting too much!

    Hmm. Have you gone into e-tube and seen what the settings are? IIRC, the R8000 FD Di2 parts have a software index adjustment. Is it centered ish? I think the FD has 20-some stops versus the RD's 30ish.
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  7. #7
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    Any chance you could have accidentally held down the junction box button for a couple seconds when adjusting your bars? When you do that and the lights flash red and green it is in adjustment mode and each push of the shift lever actually adjust the respective derailer a small amount in each direction. It would eventually time out and go back to shifting mode. Basically the fancy version of the old barrel adjuster on your cables.

    I’ve known people who put it in adjustment mode while riding, make a slight adjustment, then switch it back.


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  8. #8
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    Quote Originally Posted by Marc View Post
    Hmm. Have you gone into e-tube and seen what the settings are? .
    No, I'll do that tomorrow.

    When I picked up the bike Shimano had actually sent the wrong battery charger (BCR1 instead of BCR2, which I'm swapping over tomorrow) so will be able to have a more thorough look. I have only been using the mobile app to check the initial setup of gears and Garmin integration etc and I don't recall seeing any of the micro adjust details in the app. The shop had already updated all the device firmware prior to me picking it up.

    I thought the RD was only 16 steps of adjustment, but could be very wrong there!

  9. #9
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    Quote Originally Posted by golfnbike13 View Post
    Any chance you could have accidentally held down the junction box button for a couple seconds when adjusting your bars? When you do that and the lights flash red and green it is in adjustment mode and each push of the shift lever actually adjust the respective derailer a small amount in each direction. It would eventually time out and go back to shifting mode. Basically the fancy version of the old barrel adjuster on your cables.

    I’ve known people who put it in adjustment mode while riding, make a slight adjustment, then switch it back.


    Sent from my iPhone using Tapatalk
    I thought the flashing red/green was for comms mode to the eTube app and adjustment mode was solid red after holding the button down longer??

    It's possible I bumped something while adjusting the bars, that's why I mentioned it. I disconnected the rubber band and used a K-Edge A-Junction holder which is a neat little device that fits in the spacer stack, but would have to be fairly ham fisted to nail that little button for long enough to enter adjustment mode (in the right gear combo for FD adjustment) and then mess up the FD settings. Not impossible, but highly unlikely I think.

  10. #10
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    Quote Originally Posted by TmB123 View Post
    No, I'll do that tomorrow.

    When I picked up the bike Shimano had actually sent the wrong battery charger (BCR1 instead of BCR2, which I'm swapping over tomorrow) so will be able to have a more thorough look. I have only been using the mobile app to check the initial setup of gears and Garmin integration etc and I don't recall seeing any of the micro adjust details in the app. The shop had already updated all the device firmware prior to me picking it up.

    I thought the RD was only 16 steps of adjustment, but could be very wrong there!
    The RD is 16 steps on either side of center. I was wrong, the FD is 18 steps either side of center.

    See Shimano's Dealer's Manual, starting pg129:

    https://si.shimano.com/pdfs/dm/DM-R8050-01-ENG.pdf
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  11. #11
    'brifter' is a lame word.
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    Quote Originally Posted by golfnbike13 View Post
    Any chance you could have accidentally held down the junction box button for a couple seconds when adjusting your bars? When you do that and the lights flash red and green it is in adjustment mode and each push of the shift lever actually adjust the respective derailer a small amount in each direction. It would eventually time out and go back to shifting mode. Basically the fancy version of the old barrel adjuster on your cables.

    I’ve known people who put it in adjustment mode while riding, make a slight adjustment, then switch it back.


    Sent from my iPhone using Tapatalk
    Wrong. When you push the button for @ 1-2 seconds the red led comes on. That is adjustment mode. When you're done adjusting and you push the bottom again the green/red leds either come on or flash 2 or 3 times to let you know which shift mode you're in.
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  12. #12
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    Quote Originally Posted by Marc View Post
    The RD is 16 steps on either side of center. I was wrong, the FD is 18 steps either side of center.
    I knew there was a 16 somewhere!

    I'm half thinking that somehow the offset setting got corrupted, was maybe set for say -10 and somehow became +10 (as an example).

    Is it at all possible that applying heat to the eTube wiring (to the shrink wrap) could produce an electrical anomaly to corrupt the FD settings? Bit of a long stretch, but it's the only thing that I DID do, then on the next ride there was a problem, it is one hell of a coincidence however unlikely.

  13. #13
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    The shop has asked me to bring the bike in tomorrow when I pick up the charger, they want to check it over as said it is quite unusual.

  14. #14
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    Just as a follow up to this, I swung byt the shop yesterday and got them to look at the bike. Seeing as how I’d already “fixed” it, there wasn’t a lot for them to see, they weren’t sure why I had to adjust the High Limit screw so much, unless the screw vibrated loose somehow, maybe some loctite if it does it again. They confirmed its unlikely that it could electrically adjust itself that far out of whack.

    They did a few minor tweaks and all is good again.

    fwiw, I checked the e-tube software today, the RD was set at about -14 stops and the front at -4.
    The RD offset seems a bit excessive, is it possible to zero out the offset and start again or just leave well enough alone?

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