Di2 stopped working, Di2 started working, any idea why?


Well-Known Member

I turned up for a sportive at the weekend got a mile down the road and hit the first hill so I hit the left hand lever to change down to the small ring on the front and nothing happened. The battery was charged and the rear mechanism worked perfectly. I did the whole event without a small ring which it turned out wasn't too bad as the course was fairly flat. I am due to do a very hilly ride as part of a half Ironman in a month though so I need to get it sorted.

So, back home and with the bike on the stand I started to investigate only to discover that it now works perfectly. There does not appear to be any wires loose and I had not touched the bike so I now have no idea what was wrong but feel uncomfortable with the thought that the thing can just stop again when it feels like it.

Any ideas what could have happened?



Über Member
My money is on a loose/damaged wire. I had an incident where I fell down some stairs with my bike and banged the RHS leaver, this rotated it slightly on the bar which was enough to dislodge the connector, I'd peel back the cover of the offending break leaver and give the connector an examination. Is the cable overly taught? Give the connector a good push home in to the leaver (if you don't have the proper tool, needle nose pliers should do.)

Similar on the FD as well. Also worth checking the battery connection too. There's a junction box around the BB area too, but more problematic to access I would expect.

Sounds like its going to be an intermittent problem, so not something that might be detectable using the standard e-tube diagnostics. Not sure if the more expensive interface that the LBS might have will show any logging info, might be worth a google/phone call to them?


Cracking a solo.
This is the great worry with all things electronic - intermittent problems. I hope this is a one-of occurrence.
I agree, it's why I stuck with cables on my new bike. I'm sure it's all been tested to destruction and all the rest but it was enough of a concern to put me off, but then a cable can snap so meh, I dunno, whatever. Anyway, good luck OP, hope you get it sorted with no recurrent dramas :okay:


Failed Tech Bro
In a year I've only had one funny with my Di2 - the rear derailleur went into safety mode and wouldn't go into the lowest 5 sprockets. I just did a reset at the junction box by holding the button for >5 seconds and everything came back to life. No idea what caused it though.


Voice of the people
My rear derailleur stopped working after Di2 was installed after about a week for no reason.
After checking the connection on the unit I then carefully unraveled the bar tape on that side and it was a dodgy connection to the shifter luckily. It looked ok, but had just minutely popped out from the clicked in position for no reason. Maybe it wasn't a good enough connection in the first place, I dunno.
I was just a bit relieved I didn't have to check the battery or junction box; not difficult, just awkward.
I hope it doesn't happen again for you.
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