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  1. #1
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    Casette/chain problem

    Lo,

    I bought a GT avalanche 3.0 2005 recently, and within the first 30miles
    I had trouble with the casette/chain.

    It seems that when using any of the chainrings, and the higher sprockets
    at the rear (smaller cogs) my chain climbs and drops a gear or so whenever
    I put a little power in.

    It's making it impossible to ride, as the chain just jumps up and down a
    gear all the time.

    I thought perhaps the chain was faulty/damaged so I replaced it with a
    new 8 speed SRAM, which seemed to work fine for the first 2miles or so,
    now I'm getting the beginnings of the same problem.

    The bike was prebuilt except for the usual handlebar/pedal adjustments
    etc out of the box.

    From turning the cranks while on a stand, I can see that the chain is
    almost making contact with the next cog (lower gear) every now and then
    as it leaves the casette. (This is not because of the deraileur)

    Might the casette have the spacers positioned incorrectly or be damaged
    in some way? To my untrained eye, it looks undamaged.

    # Gears: 24 speed Shimano XC-202 front and Acera rear derailleurs
    # Shifters: Shimano ST-EF29 gear shifters
    # Chainset: Suntour XCC-252 chainset with 42-32-22 teeth chainrings

    EDIT: Image
    (top view of rear derailleur in 8th gear)

    I'm aware that you're not really supposed to use certain gears where the
    chain is forced to bend, but this problem happens in a range of gears,
    even where the chain is straight (largest front cog + smallest rear cog).

    Any suggestions?

    Thanks

  2. #2
    Meh.
    Reputation: XSL_WiLL's Avatar
    Join Date
    Nov 2004
    Posts
    17,516
    Quote Originally Posted by Akuma
    Lo,

    I bought a GT avalanche 3.0 2005 recently, and within the first 30miles
    I had trouble with the casette/chain.

    It seems that when using any of the chainrings, and the higher sprockets
    at the rear (smaller cogs) my chain climbs and drops a gear or so whenever
    I put a little power in.

    It's making it impossible to ride, as the chain just jumps up and down a
    gear all the time.

    I thought perhaps the chain was faulty/damaged so I replaced it with a
    new 8 speed SRAM, which seemed to work fine for the first 2miles or so,
    now I'm getting the beginnings of the same problem.

    The bike was prebuilt except for the usual handlebar/pedal adjustments
    etc out of the box.

    From turning the cranks while on a stand, I can see that the chain is
    almost making contact with the next cog (lower gear) every now and then
    as it leaves the casette. (This is not because of the deraileur)

    Might the casette have the spacers positioned incorrectly or be damaged
    in some way? To my untrained eye, it looks undamaged.

    # Gears: 24 speed Shimano XC-202 front and Acera rear derailleurs
    # Shifters: Shimano ST-EF29 gear shifters
    # Chainset: Suntour XCC-252 chainset with 42-32-22 teeth chainrings

    EDIT: Image
    (top view of rear derailleur in 8th gear)

    I'm aware that you're not really supposed to use certain gears where the
    chain is forced to bend, but this problem happens in a range of gears,
    even where the chain is straight (largest front cog + smallest rear cog).

    Any suggestions?

    Thanks
    Kink in the chain? Improper chain length? Cable tension? Bent derailleur hanger? Bent cogs? Improperly adjusted high/low screws?

  3. #3
    mtbr member
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    It's Your Components

    I had the same problem on my 1st bike (a 300.00 Trek). It had an Altus, Acera drive train. And cheap SRAM Grip Shifters. It skipped alot and required contstant adjustment.
    I bought a Shimano XT rear der. LX front der. and SRAM Rocket 8spd. Gripshifters.
    I adjusted it once.......... the day I installed it. I run 9spd now and it's even better.
    I think that if you upgrade to some precision components your problem will go away.
    The stuff you have now is low end, adjusting it properly will help but you won't get
    the reliable performance that higher end components have to offer.
    Good Luck

  4. #4
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    Quote Originally Posted by plazcek
    I had the same problem on my 1st bike (a 300.00 Trek). It had an Altus, Acera drive train. And cheap SRAM Grip Shifters. It skipped alot and required contstant adjustment.
    I bought a Shimano XT rear der. LX front der. and SRAM Rocket 8spd. Gripshifters.
    I adjusted it once.......... the day I installed it. I run 9spd now and it's even better.
    I think that if you upgrade to some precision components your problem will go away.
    The stuff you have now is low end, adjusting it properly will help but you won't get
    the reliable performance that higher end components have to offer.
    Good Luck

    Thanks for the reply

    I've been reading various forums a lot since I decided to get a new bike, so I wasn't
    expecting quality components on something as cheap as the Avalanche 3.0 2005,
    but I did expect it to work properly for a least a while with it's default components though

    I would love to go out and buy a decent casette/chain/derailleurs/etc but without
    being sure that's the problem I don't want to spend that sort of money just yet.

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