Di2 rear derailleur won't stay in largest gear?
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  1. #1
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    Di2 rear derailleur won't stay in largest gear?

    Hey there, just got my first bike with electronic shifting (Specialized Roubaix) and I'm loving it, except for one thing: it won't stay in the largest gear. It'll go down to that gear, but about 5 seconds later it pops back to the next-largest.

    I thought it was just an alignment issue so I did the microadjustment, but still had the same issue. I then watched the mechanism more closely and realized that it's not an alignment thing, the derailleur is actually shifting back after five seconds or so.

    Very strange and I'm a bit stumped. Would normally run down to my LBS but... yeah. Quarantine.

    Appreciate any suggestions.

  2. #2
    tlg
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    It sounds like the limit is set wrong.

    Is your LBS closed? Most are allowed to remain open for service.
    Custom Di2 & Garmin/GoPro mounts 2013 SuperSix EVO Hi-MOD Team * 2004 Klein Aura V

  3. #3
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    Thanks for the reply. They're open but limited hours and it's a bit of a process of scheduling an appointment, leaving the bike, coming back later, etc. And it's a bit of a drive. And frankly I'm doing my damndest to keep human interaction to a minimum.

    Is this just a matter of adjusting the limit screws like on a traditional derailleur?

  4. #4
    tlg
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    Quote Originally Posted by BobDobalina View Post
    Thanks for the reply. They're open but limited hours and it's a bit of a process of scheduling an appointment, leaving the bike, coming back later, etc. And it's a bit of a drive. And frankly I'm doing my damndest to keep human interaction to a minimum.
    Gotcha. Yea can be a bit of a hassle. Plus, always better to be able to do it yourself.

    Is this just a matter of adjusting the limit screws like on a traditional derailleur?
    Yes, more or less.

    Page 129 of the Manual
    https://si.shimano.com/pdfs/dm/DM-R8050-02-ENG.pdf


    This is a really good site for Di2 info.
    This page is pretty much copied from the Di2 manual in an easy to follow guide.
    https://di2center.com/2019/04/25/how...ar-derailleur/


    Older Di2 but essentially the same.
    Custom Di2 & Garmin/GoPro mounts 2013 SuperSix EVO Hi-MOD Team * 2004 Klein Aura V

  5. #5
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    Thanks very much, sounds like the overshift feature he mentions in the video may be what I'm seeing. I was confused why it would shift into gear then shift out again. Will give that a shot. Thanks!

  6. #6
    tlg
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    Quote Originally Posted by BobDobalina View Post
    Thanks very much, sounds like the overshift feature he mentions in the video may be what I'm seeing.
    Yes, that's exactly what it sounded like to me too.

    I had it happen once, but it was on the large cog. What a b!tch going up a steep hill and it keeps shifting back after a few seconds.
    Custom Di2 & Garmin/GoPro mounts 2013 SuperSix EVO Hi-MOD Team * 2004 Klein Aura V

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