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  1. #1
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    Back Pedal and Chain Slacks Onto Stays

    When I am not pedaling forward, with a slight movement backwards on the pedas, the chain slackens and scrapes on the stays, removing paint. When I get off the bike and observe closely, moving the crank backwards, slowly, it seems that the derailleur arm is giving a little bit, rather than staying firm. Not sure if this is the problem.

    This is a Marin Hawk Hill, front suspension bike with a Deore rear derrailleur.

  2. #2
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    Quote Originally Posted by JonDCH
    When I am not pedaling forward, with a slight movement backwards on the pedas, the chain slackens and scrapes on the stays, removing paint. When I get off the bike and observe closely, moving the crank backwards, slowly, it seems that the derailleur arm is giving a little bit, rather than staying firm. Not sure if this is the problem.

    This is a Marin Hawk Hill, front suspension bike with a Deore rear derrailleur.
    It sounds like you may have one or more bent/stiff links which are catching in the derailleur as the bent/stiff links pass through the rear derailleur.

    Another cause could be an out of adjustment rear derailleur. If the derailleur is adjusted such that the sides of the chain links are allowed to rub on a larger cog on the cassette as the bike is pedalled backwards, a similar but smaller jumping effect would be observed.

    What is the frequency of the derailleur jumping and how much does it move around?
    There is no added value to my participation - in fact, just more confusion.

  3. #3
    All 26.5" all the time!
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    Check your rear hub too. The freehub body might be gummed up. Remove the rear wheel and check if the gears spin smoothly in one direction only.

  4. #4
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    Yes, and also check the deraileur cogs as well too. Mine had a lot of grit and dirt in them and caused me the same problems. Once I took them apart, cleaned and relubbed them, this problem went away.
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  5. #5
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    Get a chainstay protector like a Lizardskin or make your own out of an old tube. Even when the tension is right you'll still get strikes. Protectors do a good job of saving your paint and reducing the noise.
    [SIZE=1]"The mouth of justice contemplates wisdom."[/SIZE]

  6. #6
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    follow-up

    Thanks for all the great feedback and advice.

    The bike is pretty new and has been kept clean. No muddy rides. Mostly city, some dirt trails. Anyway, I don't think it is dirt or gumming up. Just a hunch.

    What I did notice is that when I shift up to the larges chain ring, thus increasing chain tension, the problem goes away. So, it looks like I need to increase chain tension. Best way to do this?

  7. #7
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    Quote Originally Posted by JonDCH
    Thanks for all the great feedback and advice.

    The bike is pretty new and has been kept clean. No muddy rides. Mostly city, some dirt trails. Anyway, I don't think it is dirt or gumming up. Just a hunch.

    What I did notice is that when I shift up to the larges chain ring, thus increasing chain tension, the problem goes away. So, it looks like I need to increase chain tension. Best way to do this?

    My guesses are either a bent chain link or two, or your freehub body is not functioning properly. Have you tried taking the rear wheel off the bike and seeing how well the cassette spins when you try to move it with your hand?

  8. #8
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    Perhaps your chain is too long. This would cause that problem. Just make sure you don't shorten it too much.

  9. #9
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    Quote Originally Posted by JonDCH
    Thanks for all the great feedback and advice.

    The bike is pretty new and has been kept clean. No muddy rides. Mostly city, some dirt trails. Anyway, I don't think it is dirt or gumming up. Just a hunch.

    What I did notice is that when I shift up to the larges chain ring, thus increasing chain tension, the problem goes away. So, it looks like I need to increase chain tension. Best way to do this?
    One way to increase chain tension would be to apply more tension be screwing in the B-tension screw. However, this screw should only be used for adjusting the clearnace between the top g-pulley and the cassette to optimize shifting. If you are in the small chainring and the large sprocket, the B-tension screw should be adjusted so the top g-pulley isn't in contact with the cog. This may be the cause to your problems too.

    The second way to increase tension would be to remove two chain links. However, with this you have to be aware that this may make your chain short enough that if you accidently shift into big-big combo it WILL rip the derailleur and derailleur hanger off your bike.
    There is no added value to my participation - in fact, just more confusion.

  10. #10
    83 feet less per minute
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    I've had this happen when I installed the cassette onto a WTB LL hub. It requires a spacer to keep the cassette from rubbing the hub. It will rub just enough to keep it from turning backword as it should. Check to make sure the cassette spins freely.
    Want to ride in this life and the next? Ask me how.

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