New dura-ace chain, skipping cassette?

Turnbull2000
Turnbull2000 Posts: 189
edited July 2012 in Workshop
Hi,

I'd been running a Dura-ace 7901 chain on a 7800 cassette without trouble, but a link connection gave way a couple of months ago and had been running two links short ever since. Today I finally fitted a new chain, but it seems to be skipping when on the inner cassette rings on the downward stroke under pressure. I'm seeing the rear rear derailleur forward then jump back into place each time the chain skips. Is this consistent with a worn cassette?

Comments

  • smidsy
    smidsy Posts: 5,273
    Sounds like a new cassette is required
    Yellow is the new Black.
  • Turnbull2000
    Turnbull2000 Posts: 189
    OK, I've ordered a new cassette. Couldn't find a 7800, so had to pay more for a 7900 cassette instead :(

    I'm a tad concerned that the chain skip is also down to lack of tension in the rear dérailleur after being pulled further forwards than usual thanks to the old chain being shortened. Hope not!
  • robgod
    robgod Posts: 39
    I'm no mechanic but I wouldn't have thought chain tension would cause skipping. It makes more sense that the skipping chain was due to the cassette teeth being worn.
    Another thing to check though is to make sure every single link has free movement. A poorly fitted pin can cause the link to be stiff and that would cause problems - especially round the sprockets and rear mech jockeys.
  • Meds1962
    Meds1962 Posts: 391
    You can get 7800 cassettes on Wiggle, CRC etc
    O na bawn i fel LA
  • nferrar
    nferrar Posts: 2,511
    Unless it's on a bike you actually race I wouldn't have spent money on a DA model cassette, they cost a fortune. Just go 105/Ultegra level for cassettes (or the SRAM equivalent)...
  • islwyn
    islwyn Posts: 650
    I'm in the EXACT same position, new chain but no new cassette = mistake.
  • dragonontheedge
    dragonontheedge Posts: 496
    Islwyn wrote:
    I'm in the EXACT same position, new chain but no new cassette = mistake.

    Sure does.
    Hey, maybe you haven't been keeping up on current events, but we just got our asses kicked, pal!
  • scott_w1987
    scott_w1987 Posts: 316
    Also best checking your front rings too, if they are quite worn they will just wear the new chain faster.
  • gds08
    gds08 Posts: 948
    Sounds very much like a stiff link to me. Try putting the bike in its highest gear (big ring small sprocket) and wind the pedals backwards very slowly and you should be able to spot a stiff link when it kinks upwards. If you find one, note where it is then hold the chain in your hands either side of it and try to bend the chain sideways back and forth a few times. It wont break or bend but it will loosen the tight pin and solve the problem.
    Graham

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