Shimano XT rear mech snapped

The Bear

Esteemed Pedelecer
Sep 10, 2017
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Think my rear derailleur now ends replacing!!!

After replacing my snapped rear derailleur hanger last January, I pretty much stopped ring the bike in March when lockdown started. Went out on it recently and noticed the new KMC E11 chain had a broken link. Couldn't work out how it had broke after just 2 months of use???

Anyway, after replacing my chain today I could hear a grating noise when spinning the crank and noticed the chain was catching on the rear derailleur, right at the bottom where I've put the arrow. Looks like its twisted and perhaps caused the chain to snap??

Do we reckon I now need a new rear derailleur, shame if so as the Shimano XT RD-M8000-SGS is about £70 :confused:


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vfr400

Esteemed Pedelecer
Jun 12, 2011
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It looks like the bearings in the jockey wheel have gone, which might be the root of all your problems. You can replace the jockey wheel on its own. If the bearings are OK, just bend it straight.
 
Last edited:

soundwave

Esteemed Pedelecer
May 23, 2015
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that thing is pissed like a banana id not bother trying to bend it back it is to far gone unless you can find parts and rebuild the bottom part but you need to take the clutch apart to do this.

bottom jockey wheel looks like the bearing failed and broke the last chain and bent it like that going up and down the gears.
 

The Bear

Esteemed Pedelecer
Sep 10, 2017
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South Yorks
Might be a easier to just get a new derailleur then. Not cheap this cycling milliarke is it :)

Is it an easy bolt off & on job?
 

soundwave

Esteemed Pedelecer
May 23, 2015
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yes if the mech hanger is not bent!
 

soundwave

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May 23, 2015
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it is just not you ;)
 

The Bear

Esteemed Pedelecer
Sep 10, 2017
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South Yorks
The derailleur hanger snapped when this whole saga started. back in January 2020 (see first post). A broken chain link dragged the derailleur around the cassette, snapping the hanger (you found me a replacement hanger :) ).

With the new hanger fitted all then seemed ok, and I twisted the derailleur back into shape, but clearly it wasn't as ok as I assumed. The new £35 ebike specific KMC E11 chain must have been scraping on the derailleur causing the chain to snap again. I've now ordered a new derailleur so hopefully this should resolve the matter, fingers crossed.
 

vfr400

Esteemed Pedelecer
Jun 12, 2011
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As I said, it looks like the bearings have gone in the jockey wheel, which has made it go crooked so that the chain catches on the side of the cage. That's the thing that needs attention.
 

soundwave

Esteemed Pedelecer
May 23, 2015
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soundwave

Esteemed Pedelecer
May 23, 2015
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as soon as any muck gets in the bearing and left it destroys them in no time at all so needs checking now and then esp the bottom one.
 

The Bear

Esteemed Pedelecer
Sep 10, 2017
517
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South Yorks
Good video, thanks soundwave, I'll keep an eye on the bearings in future.
 

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