Front Derailleur Ghost Shifting Shimano 6870

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djwalker
Posts: 165
Joined: Sat Oct 31, 2009 7:35 pm

by djwalker

I have an occasional ghost shift from the large chainring to the small chainring when I shift the rear derailleur of my 11 speed 6870 system. This happen while in the big ring when shifting from the 2nd largest to the 3rd largest cog or from the 3rd largest to the 4th largest cog (going toward smaller cogs). It only happens occasionally. Maybe 1 shift in 20 or so when I shift the rear the chain will drop to the small ring. As near as I can tell the front derailleur doesn't move in the process. The Di2 auto-trim function seems to have the front D in a position toward the small ring a bit to prevent chain rub when on the larger cogs. The chain is a KMC 11 speed chain. Does anyone have any idea why this might happen? What makes it derail just occasionally? Is it something to do with the setup, the chain, ???

Thanks for the help.

NiFTY
Posts: 1493
Joined: Sat May 26, 2012 11:26 pm

by NiFTY

Mate, i had an identical situation with my two SRAM Red bikes, running KMC x10sl chains. I had been running those chains and sram for ages without issue. Chainrings were not worn, cassettes were not worn. I had recently changed my lube regimen ( i was using bike milk, an australian dry lube when the issue started). Neither chain was stretched, according to my KMC chain wear tool, they had 2100 and 1500 K on them. I changed the chains. Problem gone. Change your chain, it will be fixed. Let me know what lube you were using out of interest.
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djwalker
Posts: 165
Joined: Sat Oct 31, 2009 7:35 pm

by djwalker

I use Prolink Gold lube. The KMC chain is virtually new and the old one did it as well. One thing I am wondering about is the quick link. If its dimensions are a little bigger than a standard link it conceivably could cause problems with the narrow 11 speed spacing.

oreoboreo
Posts: 510
Joined: Tue Aug 09, 2011 2:25 pm
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by oreoboreo

I am sure you know this... the KMC quick link comes in 11 speed and 10 speed. Just a thought, if you happen to have the 10 on an 11 speed system I could start the shift??? just an idea, change the quick link
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maccpres
Posts: 46
Joined: Tue Feb 14, 2006 8:11 pm
Location: Atlanta

by maccpres

I had ghost shifting with 10 speed ultegra di2. It would shift to the small ring without me touching a thing. The shimano rep updated my firmware but I kept getting the ghost shift. It was fixed when shimano replaced my front deraillure. It's been fine ever since.

djwalker
Posts: 165
Joined: Sat Oct 31, 2009 7:35 pm

by djwalker

The quicklink came with the 11 speed chain and looks to be correct. I was thinking that the pins might stick out a little farther or the plates be just slightly wider or something. Don't know why that would cause a front shift though.

pandaoz
Posts: 4
Joined: Mon Apr 04, 2016 1:16 am

by pandaoz

I just wanted to resurrect this thread as I also have this issue having recently upgraded to Di2.

Once again, it looks like I am getting a random shift from the large chain ring to the small chain ring maybe 1 in 50 shifts or so on the rear cassette. There is no chain rub on the front cage in any gear, the trim is working fine and I cannot replicate this ghost shift on the workstand. Has anyone had similar experience and if so have you got a solution ??

XCProMD
Posts: 1123
Joined: Sat Jan 26, 2008 10:25 am
Location: Cantabria

by XCProMD

Yes it's something that keeps happening to a number of Di2 users. So far I have only seen it being solved by substituting the FD.

pandaoz
Posts: 4
Joined: Mon Apr 04, 2016 1:16 am

by pandaoz

Wow I hope this isn't the only option! If this is a known problem, is Shimano replacing FDs under warranty ?

XCProMD
Posts: 1123
Joined: Sat Jan 26, 2008 10:25 am
Location: Cantabria

by XCProMD

That depends a bit on the diagnostics that your SC makes and if you FD is still in warranty period

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ms6073
Posts: 4288
Joined: Fri Jul 23, 2004 8:24 pm
Location: Houston, Texas

by ms6073

XCProMD wrote:FD is still in warranty period

Good point as the warranty for 9070 components is 3-years from date of purchase, so that anniversary may already have passed for early adopters.
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pandaoz
Posts: 4
Joined: Mon Apr 04, 2016 1:16 am

by pandaoz

Thanks for the replies. The FD is definitely still under warranty as it was purchased new. Problem is the shift happens so randomly that I haven't been able to replicate it on the workstand despite shifting up and down the cassette for almost an hour!
Does anyone know if this error has been identified using the etube diagnostics ?

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