Chain falling off Question?- Mtbr.com
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  1. #1
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    Chain falling off Question?

    Just put a new PC-1 chain on. Had the chain snug to tight in tension. Raced today and 30 minutes into race the chain fell off 4 tomes untill i had to pull off! My eccentric bottom bracket seemed to be in place,, could the chain stretched that much in 30 minutes???

  2. #2
    Bike Dork
    Reputation: sin3kal's Avatar
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    I would check your chainline is good. and look for broken, bent teeth on your chainring and cog.

  3. #3
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    does your chain ring and cog have MONSTER teeth?

  4. #4
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    Was your chain too snug? You probably already know, but chainrings and cogs arnt made perfectly circular so it needs a little slack to tighten and loosen so I can see excessive stretch of a singlespeed without enough chain slack.

  5. #5
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    PC-1 does that sometimes.
    I had it 4 times in a row during a singlespeed race a few years ago.
    Turned out my chainline was off by more than a few mm.
    Belgian beer and Scotch whisky.

  6. #6
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    Quote Originally Posted by rustyenduro
    Was your chain too snug? You probably already know, but chainrings and cogs arnt made perfectly circular so it needs a little slack to tighten and loosen so I can see excessive stretch of a singlespeed without enough chain slack.
    Yah I think you have the answer, my mechanic thinks that is what happened. Thanks for the input.

  7. #7
    Schipperkes are cool.
    Reputation: banks's Avatar
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    1/8" pitch chains blow for off road "racing". Too wide on normal 3/32" c-rings & cogs......

    Get yer chain line dialed, buy a 3/32" pitch 8-9 speed chain and fling that 1/8" POS away
    Quote Originally Posted by mikesee
    Better suited to non-aggressive 125# gals named Russell.
    I ride so slow, your Garmin will shut off.

  8. #8
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    My chain has fallen off ~3 times in 3 or so years. Chain line is spot on. Chain tension is just right.

    After much study, I discovered the culprit. I've never seen anyone mention this same cause before...

    Seems that there's a lot of 'float' with my pedals, as I've been too cheap to buy new cleats.

    When cranking uphill, in extremely rare circumstances, I can get my heel to swing in and hit the chain on the upstroke of the chain ring side. (Poor technique, I know. Thx.)

    Chain pops right off. Just like that.
    Life is tough, but it's tougher when you're stupid.

  9. #9
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    ^Haha, that's a new one. Glad you got it sorted out.

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