What Causes This?

markdavidhill
markdavidhill Posts: 279
edited January 2012 in Workshop
Changing down to the small chain ring at slow speed. The cage goes over. The chain climbs up the the large ring from the bottom and goes back into the cage from the rear and jams. Released by peddelling backwards.

Thank you.
Team Madison Genesis Volare & Condor Super Acciaio

Comments

  • ugo.santalucia
    ugo.santalucia Posts: 28,273
    What?
    left the forum March 2023
  • markdavidhill
    markdavidhill Posts: 279
    It is difficult to describe. It is if the lower part of the chain (as it leaves the large chain ring) is not having enough slack removed by the tension of the rear dérailleur, hence allowing it to continue rotating back up the rear of the large chain ring and then jamming in the front derailleur cage.

    I really am trying.
    Team Madison Genesis Volare & Condor Super Acciaio
  • wishitwasallflat
    wishitwasallflat Posts: 2,927
    Is it chain suck?
    Chain suck occurs primarily when downshifting under load from the middle to the smallest chainring. The bottom run of the chain may not immediately disengage from the middle ring, and can get carried upward until it wedges betwixt the chainwheels and the right chainstay.
    This jams the crankset. Since you probably wouldn't have been shifting to the granny if you weren't already climbing, the sudden lock-up of the drive train deprives you of what little momentum you had, and you are very likely to stall and fall.

    Chain suck is commonly caused by bent chainring teeth, dirty chains, or, occasionally, burrs on the teeth of new chainwheels.

    http://sheldonbrown.com/gloss_ch.html#chainsuck

    Jonathan Levy has an extensive Web site about Chain Suck
  • sungod
    sungod Posts: 16,603
    ^^^this
    http://www.fagan.co.za/Bikes/Csuck/
    my bike - faster than god's and twice as shiny
  • markdavidhill
    markdavidhill Posts: 279
    wishitwasallflat wrote:
    Is it chain suck?
    Chain suck occurs primarily when downshifting under load from the middle to the smallest chainring. The bottom run of the chain may not immediately disengage from the middle ring, and can get carried upward until it wedges betwixt the chainwheels and the right chainstay.
    This jams the crankset. Since you probably wouldn't have been shifting to the granny if you weren't already climbing, the sudden lock-up of the drive train deprives you of what little momentum you had, and you are very likely to stall and fall.

    Chain suck is commonly caused by bent chainring teeth, dirty chains, or, occasionally, burrs on the teeth of new chainwheels.

    http://sheldonbrown.com/gloss_ch.html#chainsuck

    Jonathan Levy has an extensive Web site about Chain Suck

    Hell fire. That's what's happening. I have 'chain suck' on the Secteur.

    Both the chainrings and chain are less than 150 miles old.

    Thanks 'Wishitwas.......'
    Team Madison Genesis Volare & Condor Super Acciaio
  • Monty Dog
    Monty Dog Posts: 20,614
    Chainsuck was a common problem with many MTB drivetrains about 10 years ago, particularly with the smaller 'compact drive' chainrings. A decent quality chain like a KMC which has relieved sideplates is less prone to chainring pick-up.
    Make mine an Italian, with Campagnolo on the side..
  • nferrar
    nferrar Posts: 2,511
    I'd check for a stiff link in the chain first if it's all new stuff
  • wishitwasallflat
    wishitwasallflat Posts: 2,927
    Take it back to where you bought it and they should remedy it under warrenty in that period (remember if it less than six months old its up to them to prove its not a defective part(s)).
  • Greenmam
    Greenmam Posts: 42
    I have had the same thing on my Shimano 105 compact drive train. it looks like it was the front big ring. not had it since changing the crank to a ug dubble, 2 weeks ago. will look at a new ring and chain after the winter for it.
  • keef66
    keef66 Posts: 13,123
    What rear sprocket are you in when doing the front shift? If you're asking it to change into a combo that will involve serious cross-chaining, the big chainring might be reluctant to let the chain go.

    Try it when the chain's on the bigger sprockets and see what happens
  • markdavidhill
    markdavidhill Posts: 279
    On both occasions of 'chain suck', mid cassette.

    This has only happened since using the large Red chainring. My lbs is replacing it with a Rival and credit.
    Team Madison Genesis Volare & Condor Super Acciaio
  • wishitwasallflat
    wishitwasallflat Posts: 2,927
    Result - good lbs (its not near Darlington is it?)
  • wishitwasallflat
    wishitwasallflat Posts: 2,927
    Oops cancel last just read your location - still good result
  • ilm_zero7
    ilm_zero7 Posts: 2,213
    markdavidhill wrote:
    On both occasions of 'chain suck', mid cassette.

    This has only happened since using the large Red chainring. My lbs is replacing it with a Rival and credit.
    Ah SRAM - that explains a lot!
    http://veloviewer.com/SigImage.php?a=3370a&r=3&c=5&u=M&g=p&f=abcdefghij&z=a.png
    Wiliers: Cento Uno/Superleggera R and Zero 7. Bianchi Infinito CV and Oltre XR2
  • markdavidhill
    markdavidhill Posts: 279
    ILM Zero7 wrote:
    markdavidhill wrote:
    On both occasions of 'chain suck', mid cassette.

    This has only happened since using the large Red chainring. My lbs is replacing it with a Rival and credit.
    Ah SRAM - that explains a lot!

    Tell me about it.

    The Ultegra on the Lynskey is faultless.
    Team Madison Genesis Volare & Condor Super Acciaio

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