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  1. #1
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    XX1 Cranks Dropping Chain

    I have what appears to be a very weird and rare chain drop issue. I'm running XX1 cranks with a 1091 chain and 1090 cassette. The issue is that the chain is actually swinging out on the top side (above the chain stay, not down below between rear DR and ring) and catching the tip of the crank arm when my drive-side crank is in the upstroke. If I don't recognize what's going on, I basically pedal the chain right off the ring. The only theory I can come up with is maybe the narrow q-factor I'm running enables this. I'm wondering if a) changing to a wide q-factor will push the crank arm further from the chain and b) if anyone else has ever seen the chain catching the crank arm like this. My chain is as small/tight as possible, so it's not a chain sizing issue and I'm running the Type II rear DR. That won't make any difference since this is on the top side where chain tension can't be affected by the DR.

    I've raced XC twice this year and it has happened both times. It's very frustrating and is affecting my results. Any help is greatly appreciated!!

  2. #2
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    1) Operator inability, or
    2) Act of God to give the rest of us a small fighting chance when we line up against you!

  3. #3
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    I can't imagine this. On the top side between the cassette and chain ring, there should not be any extra chain that could possibly "swing out".

  4. #4
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    Update - I swapped out the ring to a Wolftooth wide narrow, put a new sram 1091 chain and xx cassette on. Result; dropped the chain in my race again. Chain was in the 11 tooth position. Someone somewhere has surely seen this. I'M leaning towards Q factor playing into this again. Niner has recommended that we use a wide Q factor crank in the air 9 RDO now and I wonder if they've seen this. I'm going to try to contact them and see what they think.

  5. #5
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    I think this likely confirms my option 2) as stated above. But just in case, good idea to see if Niner has any helpful input.

    Didn't I see something recently about the regional Niner rep having his demo van at SWW sometime here soon? Maybe he could help.

  6. #6
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    Quote Originally Posted by rwitte View Post
    I think this likely confirms my option 2) as stated above. But just in case, good idea to see if Niner has any helpful input.

    Didn't I see something recently about the regional Niner rep having his demo van at SWW sometime here soon? Maybe he could help.
    You're hilarious RWitte! The Niner rep was here and I didn't talk to him. I assumed my problem would be solved by replacing all those darn components!

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