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Old 08-03-15, 02:34 AM   #1
Husum89
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Shifting problems on shimano 6800 rear derailleur

Hi everyone

I had a pretty wet ride just before i went on a months vacation, and after returning, my rear derailleur won't shift to the smallest cog (highest gear). I also switched wheelset in the meantime, but the problem exist with both old and new wheelset.

I've checked the high-limit screw, and the alignment seems fine. The dropout is not bent. If i manually push the derailleur, I can get it down to the smallest cog. Also, if I step-by-step loosen cable tension on the adjustment screw (or completely unscrew the cable), it easily drops down. Problem solved? Not really - The problem then becomes, that it won't shift into second-smallest cog gear on the first lever pull, and can't switch to the largest cog.

The derailleur seems fine. This leads me to think of the cables or levers (most likely the first?) as the problem. When I adjust the cable tension to allow the derailleur to switch to the smallest cog, almost no cable movement is felt when i try to shift from the smallest cog to the second-smallest, and it stays on the smallest cog.

Since it jumps straight to the smallest cog without cable tension, and the fact that it shifts perfectly from gear 1-10 with more tension (but not to the smallest cog/11th gear), I am assuming that the derailleur is working just fine.


The bike is just 9 months old, and due to a winter injury, it has only done 2.500km. Could the cables really be worn out already?
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Old 08-03-15, 04:13 AM   #2
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I think that you are on the right track. The cables might not be worn out but may be clogged with rust or road grit, especially the lower loop going into the derailleur, which is a low spot and tends to collect water and grit; perhaps this occurred on your wet ride. I'd suggest de-tensioning the shift wire, pulling the housings runs out of their stops and check/clean/lube them. I do not usually troubleshoot by replacing parts but cables are inexpensive so when I suspect a problem with them I often just replace them. The difference with new cables is often dramatic.
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Old 08-03-15, 04:33 AM   #3
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Originally Posted by dsbrantjr View Post
I think that you are on the right track. The cables might not be worn out but may be clogged with rust or road grit, especially the lower loop going into the derailleur, which is a low spot and tends to collect water and grit; perhaps this occurred on your wet ride. I'd suggest de-tensioning the shift wire, pulling the housings runs out of their stops and check/clean/lube them.
Thank you very much for your input.

I will try cleaning the housing near the derailleur once I get home.

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I do not usually troubleshoot by replacing parts but cables are inexpensive so when I suspect a problem with them I often just replace them. The difference with new cables is often dramatic.
I have the same philosophy. Is it enough to start by just replacing the cables, or should I always replace the housing as well?
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Old 08-03-15, 04:37 AM   #4
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I always replace both since the wires and housings wear-in together (the primary cause of new cable "stretch") and the new wire may not play well in the groove made by the old one. I don't have any under-the-bar tape housings so replacement is simple.
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Old 08-03-15, 06:37 AM   #5
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With the cable disconnected, can you manually shift the bike through all 11 gears? That'll tell you if your high or low limit screws are off. I'd highly recommend cables too since it has been a little while, although I still feel they are worn out prematurely. It's not surprising though, because my road bike came with remarkably inexpensive housings and they wore out and shifted erratically for some time and it was nigh on impossible to tune the derailleurs properly. Invest in some Jagwire road pro cables as I've had great luck with them and seem to be highly rated by others as well.
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Old 08-03-15, 02:27 PM   #6
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Thank you for the input guys.


A quick update. I went riding with 10 gears today, and the source of the problem suddenly revealed itself, when the shifting completely gave out.


Below is a picture of the cable from inside the lever, including the plastic tongue. The small part was a bit of a pain to get out. Don't know how the f*** it ended up like this


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Old 08-03-15, 02:41 PM   #7
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I was just coming to post that. My GF's bike the same thing. Had me banging my head. Turned out her cable was frayed and would only shift correctly every X time. Swapped the cable out, readjusted and all was right in the world again.
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