Chain jumping off narrow wide chainring

Discussion in 'The Workshop' started by RS VR6, Jul 21, 2014.

  1. RS VR6

    RS VR6 Member

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    I kind of have an odd issue with my chain dropping off.

    The chain drops off halfway off the top of the chainring. Chain will stay on the middle part of the ring.

    The chain will drop while I'm not pedaling down a rough section of trail...I'll know the chain is off because I'll hear it rub the rear tire. I have a Bionicon dangler type chain tensioner. Is it possible that somehow the bouncing of the chain is being displaced to the top because of the tensioner? If that makes any sense.#-o

    I have the chain sized to where at full compression on the rear shock...the rear derailleur is fairly tight (still has some slack left) while in the big cog.

    The bike is a Pivot Mach 5 and has a non clutch XT derailleur with a 30T Raceface NW ring.

    Thanks!
     
  2. bing!

    bing! Active Member

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    Weird. Chain as short as possible?
     
  3. RS VR6

    RS VR6 Member

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    I think it is.

    The RD is pulled pretty straight at full compression in the big cog...but still has enough slack to let me push the cage up a bit.

    Should have taken a picture...but at the time I didn't feel like taking my gloves off and futz for my phone.:?:
     
  4. bing!

    bing! Active Member

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    Even with a non clutch derailleur, a properly cut chain with a Bionicon CG should keep the chain fairly well. This may sound stupid but, did you sync the wide teeth of the chain ring with the wider links?
     
  5. trestles126

    trestles126 Member

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    Is the chain link completely snapped in? This was happening to mine and I noticed the chain master link safety wasn't completely snapped making it just short enough to make it hop off the tooth
     
  6. RS VR6

    RS VR6 Member

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    I did not...its something I can try. :D

    I did...the master link is new...but I can always double check. :)
     
  7. bing!

    bing! Active Member

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    The whole point to narrow wide rings is for the ring to grip the chain. Wide teeth must be in wide links and narrow teeth in narrow links.
     
  8. RS VR6

    RS VR6 Member

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    Thanks man...I'll check it out.:beer:
     
  9. onlyzenki

    onlyzenki New Member

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    how is the chain line? does it drop in any particular gear combination?
     
  10. Garrett

    Garrett Active Member

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    Check the chain for wear as well. A stretched chain will drop more often than a new one.
     
  11. mfoga

    mfoga Intense Whore

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    Could also be a stiff link.
     
  12. ManInAShed

    ManInAShed New Member

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    If you can fit the wide teeth between the narrow plates, it's time to get a new chainring.
     
  13. RS VR6

    RS VR6 Member

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    Chain line seems ok. I don't remember which cog I was in when it dropped. I think it was in one one of the smaller cogs.

    Odd thing is...when the chain come off the top...it comes off the inside of the chain ring.

    I didn't notice any stiff links...but I'll double check.

    As for chain wear...it stays on when I try and pull the chain where its wrapped around the ring.
     
  14. exrcyst

    exrcyst Member

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    Race Face's narrow wide design isn't as good as Sram's x-sync. It'll drop chains more often. Anyway, in addition to some good advice above I'd check your derailleur to make sure the cage tension is still strong, and freehub body for excessive drag.
     
  15. scottay

    scottay New Member

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    How old is the NW ring? Chipped tooth maybe? I agree the rear der. tension may be weak. Try removing the Bionicon guide. I've had one that would not swing freely inboard/outboard and that would cause a bad chainline by stopping too far inboard.. Throw some triflow or chainlube at the Bionicon pivots. Or remove it for a ride.
    If it drops while you're NOT PEDALLING , I'd say that points to the rear der.

    Any chance the NW ring is bent?
    .
     
  16. dstepper

    dstepper (R.I.P.) Over the hill

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    ^ I vote for excessive drag in the rear hub. Never hurts to give it a service to keep it running smooth.
     
  17. scottay

    scottay New Member

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    So the hub is trying to push the chain fwd and off the chainring while coasting? Makes sense......
    .
     
  18. dstepper

    dstepper (R.I.P.) Over the hill

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    If when pushing a bike you see the cranks moving forward you are way past time to service the hub.
     
  19. RS VR6

    RS VR6 Member

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    Thanks for the freehub suggestion. I'll check to see if the cranks are moving forward.
     
  20. strobe

    strobe resident noob

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    MRP 1x. No clutch. No lower guide. No bash. No drops.

    Running 1x9 with a RaceFace NW. I rarely pedal backwards, so, a lower guide is unlikely to help. The upper guide seems to keep it on. At least while pedaling through chatter and softball sized chunk.
     

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