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DI2 R8050 GS trouble shifting up

Old 05-10-21, 07:11 AM
  #1  
alpanian
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DI2 R8050 GS trouble shifting up

Hi all,

This is driving me crazy. I installed Shimano DI2 myself about 1000km ago, and everything worked fine. Then after about 5-600km I start having problems shifting up. I have gone through setting it back up multiple times. It is absolutely perfect, yet still doesn't shift properly.

Essentially, in about 20% of shifts up, the rear derailleur moves up and right back down. After multiple tries it might work. Shifting down is always good.

To make it absolutely crystal clear what I'm talking about, thanks for checking out this clip:

Note that I updated firmware before install. I am wondering if there's something wrong with the unit. Has anyone experienced this before. Online I could only find reports of people not shifting into the biggest cog due to incorrect limits. But that's not the case here. My only other thought is the derailleur hanger, but I don't have a tool to check that. The bike, however, has never been dropped, so that should not be a factor.

Any help greatly appreciated.
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Old 05-10-21, 07:52 AM
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It might just be the camera angle, but your RD looks low in relation to your RD hanger. Maybe the B-link on your RD is mounted on the RD hanger in the wrong position. Something to check...
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Old 05-10-21, 09:20 AM
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Charge

Silly question..... sorry but I have to ask.

Is the battery charged and showing a "Solid Green Light" on the junction box then tested?

Barry

OH and while you're at it, have you run a crash reset on the RD?

Thought of another silly question.... what is the width of the chain, are you running a chain too wide causing the RD to think it's a failed shift.
My Shimano 11sp HG701 is 5.65mm across the rivits.

Last edited by Barry2; 05-10-21 at 09:26 AM.
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Old 05-10-21, 09:33 AM
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I would go into the setup and move the DR alignment over a position or two and see what that does. Pretty much the same thing I'd do if this was cable pulled DR. Only I'd be turning the barrel adjuster instead.

Worked good for a 1000 km. So why now? Don't know, 1000 km isn't much IMO, but you'd think it'd be enough. What else have you done to the bike? It's really clean.

Cassette lock ring loose? Changed cassettes which might need new alignment.
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Old 05-10-21, 09:43 AM
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Originally Posted by Barry2 View Post
Silly question..... sorry but I have to ask.

Is the battery charged and showing a "Solid Green Light" on the junction box then tested?

Barry

OH and while you're at it, have you run a crash reset on the RD?

Thought of another silly question.... what is the width of the chain, are you running a chain too wide causing the RD to think it's a failed shift.
My Shimano 11sp HG701 is 5.65mm across the rivits.
Thanks for your help. Yes it's charged. I also have the wireless unit installed and see the charge in realtime on my Garmin.
The chain you see on film is a CN-HG701 and the casette is a 105 11sp. The rest of the bike is all ultegra.
In fact, I swapped the cassette and chain a couple weeks ago (hence the shine) as they were aging and I figured maybe that'll help. I re-adjusted the whole system afterwards of course. But the issue still there.

With regards to the RD being too low Kabuto , wouldn't the space between the top jockey wheel and the cassette also be too big then? I have the b screw adjusted s that there's a 2-3 mm when in the biggest cog.
Iride01 yes, indeed my first thought too. I've been through micro adjust fiddling to no ends unfortunately.
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Old 05-10-21, 09:47 AM
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Originally Posted by alpanian View Post
I have the b screw adjusted s that there's a 2-3 mm when in the biggest cog.
I've just installed the same RD. Had to in order to fit a 11-34.

Try an 8mm gap between Large cog and jockey.

Barry

Last edited by Barry2; 05-10-21 at 10:37 AM.
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Old 05-10-21, 11:32 AM
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Originally Posted by alpanian View Post
... I have the b screw adjusted s that there's a 2-3 mm when in the biggest cog....
Check to make certain that there is sufficient clearance across the whole cassette, not just the big cog.
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Old 05-10-21, 11:34 AM
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Set the B-screw adjustment between 5-6mm. 2-3mm sounds awful close, and 8mm is probably too much. It doesn’t have to be “exactly” this, but get it close, key is to make sure that the top of the pulley cage doesn’t foul the big cog as you shift down. Once that’s confirmed good, forget this adjustment, it won’t move...and it is not your issue anyhow, because if it were, you’d struggle to shift down the cassette from the large cogs to the smaller cogs.

Also, your RD is shifting, so it is not in “crash mode.” Don’t ask me how I know...

I’m guessing you actually have an issue that may require replacement of the rear mech, potentially a damaged linkage, solenoid, or even motor. The fact that it is intermittent, and that you can “index” the chain to each gear, makes it quite likely that the hanger isn’t out of whack (though, it could still be possible).
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Old 05-10-21, 05:41 PM
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Originally Posted by alpanian View Post
With regards to the RD being too low Kabuto , wouldn't the space between the top jockey wheel and the cassette also be too big then? I have the b screw adjusted s that there's a 2-3 mm when in the biggest cog.
I think it would be possible to adjust the pulley to a reasonable position even with the B-link attached in the wrong position. But would shifting still work properly? I don't know. There are two tabs on the B-link, and they both need to be above the hook on the hanger. Check out the link below (post by pdlpsher dated Wed Jan 24, 2018 8:30 am towards the end of the page).

https://weightweenies.starbike.com/f...49460&start=45

Last edited by Kabuto; 05-10-21 at 08:38 PM.
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Old 05-10-21, 05:46 PM
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8mm gap works fine on mine.

So.... either
Turn in the "B" screw til the thread strips than back it off 1/2 turn.

OR

Start at 8mm and reduce the gap til it coughs again
It's a cheap test.

Barry
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Old 05-10-21, 11:49 PM
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Originally Posted by Kabuto View Post
I think it would be possible to adjust the pulley to a reasonable position even with the B-link attached in the wrong position. But would shifting still work properly? I don't know. There are two tabs on the B-link, and they both need to be above the hook on the hanger.
The OP's RD is installed correctly. It is hard to see on the video, but the angle of the bracket in relationship to the hanger is correct. I doubt it would shift as well as it is if it was wrong. In reality, it is pretty hard to get this wrong, because the shape of most hangers preclude installing the bracket improperly.

Originally Posted by Barry2 View Post
8mm gap works fine on mine.
I said "probably too much." A larger gap is certainly better than not enough, for the reason I stated above.
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Old 05-11-21, 02:18 AM
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Originally Posted by Badger6 View Post
Set the B-screw adjustment between 5-6mm. 2-3mm sounds awful close, and 8mm is probably too much. It doesn’t have to be “exactly” this, but get it close, key is to make sure that the top of the pulley cage doesn’t foul the big cog as you shift down. Once that’s confirmed good, forget this adjustment, it won’t move...and it is not your issue anyhow, because if it were, you’d struggle to shift down the cassette from the large cogs to the smaller cogs.

Also, your RD is shifting, so it is not in “crash mode.” Don’t ask me how I know...

I’m guessing you actually have an issue that may require replacement of the rear mech, potentially a damaged linkage, solenoid, or even motor. The fact that it is intermittent, and that you can “index” the chain to each gear, makes it quite likely that the hanger isn’t out of whack (though, it could still be possible).
I'm also leaning towards a faulty RD. I had already played around with b-screw adjustment, but tried again just now to no avail. And the link is definitely installed correctly. The last thing to check is hanger allignment. Guess that means a trip to an LBS. Haven't taken a bike to one in over 8 years...
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