Slipping chain/gears advice required

firebear62firebear62 Posts: 2
edited October 2007 in MTB beginners
hi, I've started mountain biking and bought a muddy fox bike. On my first time out, a steady ride along part of the trans pennine trail the chain was slipping on the back gears.
The following day I took my bike to a bike shop and had it checked. They couldn't find anything wrong with the gears. Said they were fine. :)
went out today, and the chain is still slipping along the gear cogs at the back, Awkward going through woods when the gears are all over the place. :cry:
Can anyone advise me as to how I can stop this from happening?
Many thanks

Posts

  • fabienno1fabienno1 Posts: 406
    Sounds dumb but is the chain lubed? I have this problem as well when my chain hasn't been lubed for a while... occasionally combined with the total breaking of the chain as well. Nice :wink:

    Alternatively, where the cable is exposed probably along the main tube that says the bike brand name in this case muddy fox. Change the gears down to the smallest cog, then pull the cable. If it is very loose then you need to pull some cable through.

    Do this by winding off the allen key bolt that you'll see on the derailleur that grabs the cable. Using some pliers pull it through so it is reasonably tight, but not too tight otherwise, you''ll lose the other end of the gear spectrum. However, if it is tight do the opposite, but this time make it quite loose, you shouldn't be able to pull it away from the frame more than an inch or thereabouts.

    Having done that and the gears still slip then it's now to do with the screws on the derailleur that if you look closely should say either H or L (high or low) by them. I can't remember which way these go so someone else will need to tell you this bit and make sure they are more or less level and not too wound off or tightened up.



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  • deanvwdeanvw Posts: 412
    it needs to be slightly adjusted
  • WoodywmbWoodywmb Posts: 888
    Read the section on indexing gears in Park Tools manual/web site. Or in countless other bike repair guides. Study the instructions about which way you turn the adjuster on the rear mech (depends on the model). Check there are no tight links in the chain and the derailleur is not bent. And also that there is no slack in the rear gear cable. Then fettle the gears using the detail from the bike repair guide. The bike shop should have found the problem - but it is not always obvious until the bike is under pressure (ie being pedalled hard). Learn to tune the gears and you can do it with your eyes shut. You do need to listen though: it's the actual sound of the chain engaging in each cog which tells you if the set-up is accurate.
  • If it is a new bike i would agree with all above, however if it is a second hand bike the chain may have stretched which would need a new chain and if it has badly stretched new cogs also........

    So hopefully not what i said, but this has happened to me.

    Hope that helps.
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  • easygeasyg Posts: 266
    Friend of mine has had this problem, alot and we figured it out the other day after being messed around by it so many times.

    We turned the bike upside down and, looking directly down on the derailleur, noticed that it was slightly out of line (lliterally by a mm or so) with the particular sprocket it was hung over when the chain was moving. This means the derailleur was pulling the chain off centre very slightly, which then means it ends up on top of the sprocket cogs and then jumps to the next sprocket when you continue pedalling! only to go back a few moments later. So basically the derailleur is actually putting the chain on the cog ends kind off.

    It took us ages to figure why it was doing this (wheel off, on then off again!) and then we cracked it! When the QR was used to put the wheel on, the bolt on the skewer was tightened too much, making the QR lever harder to press in which in turn was actually pulling the derailleur ever so slightly out of place (you could see it moving when the lever was put down and pulled out continually) - so we put the wheel on securely but didn't over tighten the QR bolt and lever and it stopped and (touch wood) hasn't done it since.

    I hope I have explained that clearly enough as it does sound like the same thing exactly and we can relate to how annoying it is because as you said you can't ride with it like that and if you do it will damage the components no doubt.

    Hope that helps mate, good luck - let me know if you want me to try to explain any clearer.
    "If you think straight enough, you can see round corners"
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