I rode this AM… and my rear derailleur was shifting by itself. All of a sudden it would shift down a few clicks.
How do I fix this?? Never happened before.
Flat battery?
Flat battery?
Nope…
Check that the wires are securely inserted in the sockets.
Tap and shake around the system to find if bumping can cause the shift.
Are you sure it is actually ghost shifting and not a worn chain/sprokets jumping under load?
When you say it is shifting down a few clicks, do you mean it’s jumping 3 gears in the cassette, or is it moving from one ring over to the next one? if it’s the latter, it could be a combination of the Di2 trim being off or, like someone else said, your cassette being worn or damaged & the chain not grabbing the teeth & slipping.
If it’s the former & it’s ghost shifting 3 whole gears on its own, you may want to have someone hook the system up to the computer, update the firmware, and check the specs. One thing I can think of is that it thinks you are on a 10sp when you are on an 11sp & it’s moving too much causing the derailleur to not align properly.
Sorry, that was me in the bushes with a radio transmitter!
I’d disconnect every wire from the junction boxes (if you can get to them), and re-connect. Having the shop update the firmware might not be a bad idea. And charge the battery back up to 100%. Also make sure your shift buttons don’t have water in them, that could cause ghost shifts, though I think Di2 buttons are sealed water-tight.
Connect to e-tube software and ensure there are no errors. Update all firmware.
It’s been working perfectly right up until today…
I will download the Etube software and see what happens.
mine will do this if limit screws aren’t adjusted, especially when going up steep climbs (high torque) when in the 28 tooth cog. It will keep dropping down to the next gear. fixing the adjustment screw fixes this. But, if you are hearing the servo motor during these ghost shifts, that’s another issue.
It seems like you might have entered into Shimano Di2 crash recovery mode:
http://blog.artscyclery.com/road/ask-a-mechanic-shimano-di2-crash-recovery-mode/
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I’ve noticed this on mine when it’s getting time to replace the chain.
Ah firmware problems on a bike, and software crashes, and recovery. Sounds legit.
Electronic shifting is one thing. Battery, buttons, and servos. If there’s a problem it will be obvious. Intermittent problems are almost always loose connections or corrosion.
But this is shifting by software essentially. When there’s a problem how the hell do you ever find it without swapping parts in the blind, or making random changes until the problems seem to go away? You’d need a debugger on the control box and a digital storage o-scope to find the root cause???
Ah firmware problems on a bike, and software crashes, and recovery. Sounds legit.
Electronic shifting is one thing. Battery, buttons, and servos. If there’s a problem it will be obvious. Intermittent problems are almost always loose connections or corrosion.
But this is shifting by software essentially. When there’s a problem how the hell do you ever find it without swapping parts in the blind, or making random changes until the problems seem to go away? You’d need a debugger on the control box and a digital storage o-scope to find the root cause???
I think most of us are over the “DI2 vs mechanical” debate. Pretty sure my problem will be solved pretty easily. I have been on DI2 since the very beginning, 7970 and now 9070… and this is the first time I have ever had a shifting issue. Even today… it only happened a few times on a 1.5 hour ride.