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  1. #1
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    1x10 drops chainring

    I've been singlespeeding for years and wanted to put a 1x10 on my bike. in the stand, the chain drops off the inside of the chainring as soon as I shift it into the biggest two cogs.

    setup includes:
    Jabberwocky hardtail
    XT 10 speed medium cage clutch derailleur
    SLX 2x cranks designed for non-boost 10 speed
    Absolute Black 32t oval ring (not bent or worn out)
    KMC 10-speed chain (not stretched, appropriate length)
    XT 11-36 cassette (not worn out)
    Hadley hub
    SLX 10 speed shifter

    the AB chainring has some built-in spacers so that the chain can clear the spider. is it possible that I would be better off putting more spacers on the ring to push it more inboard?

    I've used this same setup about a year ago when I put it on another bike for a few rides while recovering from a back injury and it worked fine. I worked in bike shops for a few years and know my way around a derailleur, but I've never seen a drivetrain just drop the chain over and over like this. there might be some obvious reason why it's dropping that I'll find in a closer inspection, but what possible diagnostic issues might I be missing?
    Last edited by mack_turtle; 11-22-2018 at 10:27 AM.

  2. #2
    Barely in control
    Reputation: Schulze's Avatar
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    The oval ring stands out to me as a culprit. As the high lobe turns over the top, the chain isn't going to engage the next teeth as well and is unable to keep pulling the chain over from the extreme edge of the cassette. So it falls off. I bet if you put a round ring on their your problems disappear. Also check your chain line.

  3. #3
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    Lots of people use oval rings on 1x drivetrains. How is the chainline? I'd make sure it's near centered first, if there are still problems the something must be bent or worn.
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  4. #4
    Elitest thrill junkie
    Reputation: Jayem's Avatar
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    Quote Originally Posted by J.B. Weld View Post
    Lots of people use oval rings on 1x drivetrains. How is the chainline? I'd make sure it's near centered first, if there are still problems the something must be bent or worn.
    The key there is probably the clutch derailleur that can keep tension (increase it basically) when it lets off due to the oval. Although a lot of people can "get by" with just a NW ring, put something else into the equation like a oval chainring, or FS/lots of wheel travel, real rough terrain, etc., and you need that clutch. On some derailleurs, it's adjustable (and may need to be increased).

    Other things like proper e-tension and playing with the spacing of the chainring may help.
    "It's only when you stand over it, you know, when you physically stand over the bike, that then you say 'hey, I don't have much stand over height', you know"-T. Ellsworth

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  5. #5
    since 4/10/2009
    Reputation: Harold's Avatar
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    I'd be curious if the chain is coming off at exactly the same spot on the chainring or not. Might help rule out Schulze's suggestion.

    I never had a problem with an oval absolute black chainring set up as a 1x11.

    Chainline is probably the culprit. 32t with spacers on a 2x crank tells me that the ring is going to be outboard a bit. I'd be looking at that and adjusting it if possible. How is the spacer arrangement for the bb on that bike? Moving bb spacers might make a difference, too.

  6. #6
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    The spacers that are built into the chainring put the teeth inboard a bit. I thought they were there to make the chain clear the spider, but they seem to put the teethjust about midway between where the double rings would be.

    I'll look at the chain again. Might have a twisted link.

  7. #7
    One Gear
    Reputation: .40AET's Avatar
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    Can you post a photo from the back of the bike up through the seat stays towards the crank? Also one from the front down the chain.

  8. #8
    Anytime. Anywhere.
    Reputation: Travis Bickle's Avatar
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    I suspect chainline because I have never dropped a chain on my HT with XT 11 speed and 28t oval.
    I got some bad ideas in my head.

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