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Discussion Starter · #1 ·
Gidday guys

Hopefully someone can advise if there is a difference in Shimano chains between the XTR-CN9100 and CN-M8100, one being the MTB chain, the other being the Ultegra road chain.
I have been running the XTR 12 speed chain on my R8000 Ultegra 11 speed cassette for a while now with great results (quiet, shifts well) except when I back pedal.
If I spin backward using the standard R8000 rear derailleur jockey wheels, or a set of 8150 12 speed jockey wheels, it intermittent picks up and jumps.
I am wondering if the jockey wheels only play nicely with the road version of the chain.
Seems to work fine with an old set of non Shimano jockey wheels that have lower profile teeth, but the longer Shimano pulleys stick in the chain every dozen or so links.

Hopefully someone can advise.

Regards to all.
 

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The M8100 is the XT chain (M=mountain) but it's what shows up on the Shimano site for Ultegra. They're basically the same, the XTR(D/A) chain is hollow pin and the 8100 is not. Where does it jump? Off the top of the cassette? This is normal, there isn't a derailleur to guide the chain when you back pedal. Easy fix: Don't pedal backwards unless in the cogs where chainline is most straight.
 

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Discussion Starter · #3 · (Edited)
The M8100 is the XT chain (M=mountain) but it's what shows up on the Shimano site for Ultegra. They're basically the same, the XTR(D/A) chain is hollow pin and the 8100 is not. Where does it jump? Off the top of the cassette? This is normal, there isn't a derailleur to guide the chain when you back pedal. Easy fix: Don't pedal backwards unless in the cogs where chainline is most straight.
No, it's not jumping off the cassette, it's jumping off the G pulley. The G pulley is "sticking" in the chain, and the chain is not releasing cleanly off it. Like I said, using a different jockey wheel (an old HSC ceramic) with shorter teeth, it's fine, but the Ultegra pulleys stick occasionally.
More curious than anything.
 

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Ditto, it's the wheels, but it's a combination because the 12 speed chain is narrow enough not to play nice with those pulley wheels. The 10 & 11 speed chains seem to work better on older gen pulleys
 
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