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In gear slipping

metmanmarkmetmanmark Posts: 23
edited August 2010 in The workshop
My bike was set up perfectly until I managed to come off and trash the rear dérailleur. With a bit of help from these forums it is now successfully installed.
http://www.bikeradar.com/forum/viewtopic.php?t=12723615

However, when I am in a gear (anyone) very occasionally the chain seems to slip. I had this once before when the rear cassette wasn't fully tightened but I have checked this. Everything is new - new chain, cassette & dérailleur so it is something with the setup rather than the parts. Do I need to check the length of the chain now I have a new dérailleur installed or is it the tension of the chain that needs to be tightened by adjusting the dérailleur? The gears move smoothly between gear 1-9 it is just that once or twice during my 11 mile commute it will crunch slightly whilst pedaling hard uphill etc.

Cheers
Mark

Posts

  • It sounds like you have a stiff link in your chain. What brand is the chain and does it have a split link or did you have to use a special pin to join it?
    Dolan Preffisio
    2010 Cube Agree SL
  • Could be something is distorting slightly when driven hard, just enough to catch the next gear up momentarily?
  • tri-sexualtri-sexual Posts: 672
    could be a number of things.
    i assume that the chain is the same length as the one that you've replaced.
    is front chainring ok,new chain on worn chainring can cause problems.
    stiff link in chain, inspect chain movement as it goes over the cassette when you pedal backwards, if there is a slight jump in the smoothness of the rotation then it could be stiff link. though inspect cassette at the same point to make sure that the teeth are not damaged.
    assuming all is well with the above then it is most likely to be cable length, make small adjustments until you get it right.
  • nicklousenicklouse Posts: 50,675 Lives Here
    did the mech hanger get bent in the original indecent?

    the chain is the correct length?
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • Thanks for all your responses. In reply to the questions:
    Yes the rear mech hanger was bent - I straightened it and it appears to be OK.
    I'll double check the chain length - I didn't want to start removing more links and then realise that I need to put them back again! It was a straight Deore (albeit diffferent model number) replacement of the derailleur.
    The rear cassette was replaced at the same time as the chain (about two months ago) both SRAM and decent quality (I forget the exact spec - about £18 and £24 respectively when on offer).
    Front chainring is the original ~4yrs old but looks in decent condition and the slipping has kicked in at the same time as the replacement rear derailleur so I don't think it is the front chainring.
    Will check the chain for a stiff link and the powerlink connector.

    Cheers
    Mark
  • OK - have checked out the chain rings and they are worn - the biggest one anyway. I am going to post a fresh topic on what to do next!
    Thanks guys
    Mark
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