Chain Jumping

Rory123
Rory123 Posts: 3
edited December 2010 in Workshop
Hi

Ive just finished building a Ribble TT bike with SRAM Rival deralieurs SRAM TT500 shifters. The casssette is also the 1070 10spd Sram.

My issue is that when i am in the 25tooth ring at the back and the 39t at the front. THe chain every so often falls off the inside of the chainring. Ive set the Higher and Lower limits on the derailieur so it is just not rubbing the chain but it still jumps of.

Im not using SRAM rival Cranks im using FSA Grossomer (last years ones i think)

PLz help

Rory H

Comments

  • c0ugars
    c0ugars Posts: 202
    Hi

    Are all the parts new?? if you are mixing a new chain and cassette with and old chainring, you may need to replace the chainring, due to the fact that over time the chain and chainring wear into each other and when you replace a chain sometimes you have to replace the chainring or cassette but since your problem seems to be the chainring, it might need replacing.

    If it is all new you might have a stiff link in your chain. Try turning the pedals backwards and see if any links fail to move or have minimal movement.

    Hope this helps
  • Rodrego Hernandez
    Rodrego Hernandez Posts: 1,436
    No reason why that shouldn't work - if you have a chainset / bottom bracket that aren't meant to be used together that can increase the distance of the chainset from the frame but I don't think that would be possible with an FSA chainset.

    Check the chain and make sure that thee are no irregularities that could be making it jump.

    Does it do that when riding on the road? A spacer between the cassette and wheel might help but might movce the smallest sprocket too close to the drop out.
  • keef66
    keef66 Posts: 13,123
    Not a solution, but can you fit a Deda Dog Fang to your frame?
  • Monty Dog
    Monty Dog Posts: 20,614
    Is your chain the correct length - try taking a link out? I doubt it's chainline if you're using a MegaExo crank and assuming they're all new parts - doesn't appear to be incompatability issues either
    Make mine an Italian, with Campagnolo on the side..
  • cycletech
    cycletech Posts: 44
    As Monty Dog says Chain is to long.
    When you are in the smallest sprocket and the smallest chainring. Is the rear gear mech taking up the chain tension? if not take out links until the mech moves forward to take up the slack in the chain

    This gear you would not use when riding!
    Mobile Bicycle Mechanics Specialist http://www.cycletechuk.co.uk
  • Rory123
    Rory123 Posts: 3
    Ive had a look at the chain and the powerlink isnt engaged properly, Ive tried getting it to lock like they say to but i cant get it to click in.

    ANy suggestions?

    Cheers for the help
  • tx14
    tx14 Posts: 244
    i'm with rodrego. it seems like the chainrings are too far to the frame. checking the chain length won't hurt though.
  • Rodrego Hernandez
    Rodrego Hernandez Posts: 1,436
    Rory123 wrote:
    Ive had a look at the chain and the powerlink isnt engaged properly, Ive tried getting it to lock like they say to but i cant get it to click in.

    ANy suggestions?

    Cheers for the help

    wrong powerling for the chain you have.
  • keef66
    keef66 Posts: 13,123
    "wrong powerling for the chain you have"

    Good suggestion Yoda

    What chain are you using?? If it's an SRAM 10 speed it should have a Powerlock. If you really do have a Powerlink, then either you have a 9 speed chain or lower, or the wrong link for your 10 sp chain.
  • Rodrego Hernandez
    Rodrego Hernandez Posts: 1,436
    Sorry, I meant it is the wrong powerlink for the chain that you have!

    I think that some of the KMC have a 9 or 10 written on them and maybe even a C or S for shimano or campag. It is possible to close a link onto a chain that is too wide but only just and it will result in a stiff link (ooo err)

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