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  1. #1
    Future Rainbow Jersey
    Reputation: ziggurat22's Avatar
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    Chain thrown into spokes, but only under extreme load...

    Hey guys,

    I've been having an issue with my r/d. It shifts perfectly and runs smoothly like 97% of the time. However, when I'm in the lowest gear possible on a nasty, steep, rocky climb, the derailleur sometimes throws the chain into the spokes. It's weird as I can put the chain back on to gear and continue on as if it didn't happen. However, it sucks when I'm climbing something pretty techie knowing that maybe the chain will go into the spokes. It's not a ride killing problem, but from a psychological standpoint, it's unnerving know there's a chance your equipment will fail you in a critical spot.

    Can this be fixed by adjusting the L limit screw on the r/d? I ask because I don't want to mess up the shifting as the shifting and pedaling are otherwise pretty smooth outside of these extremely high-stress situations.

    Thanks.
    "If I can't work to make it...I'll rob to take it..."

  2. #2
    Do It Yourself
    Reputation: Homebrew's Avatar
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    Throwing the chain into the spokes is a classic sign of a bent derailleur hanger. Check with a DAG. Might just be bent a little so it works fairly well most of the time. The other thing to check is your derailleur. If the pivots are getting a bit wobbly, it might be flexing under power but be fine under lighter conditions.
    Long Live Long Rides

  3. #3
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    Do as hombrew suggests, but....

    don't neglect the low limit screw either. Check the hanger alignment and correct it if needed, and check the derailleur pivots for slop, then check your L limit setting as well. To check your low limit, shift to the small cog up front and then the big one in the back just like you were climbing. This should be done in a stand of course. Stop the rear wheel and then push the the thumb lever of the shifter while looking at the rear D. The derailleur SHOULD NOT MOVE when you push the lever. If it does you need to tighten the L limit 1/8 turn and push the lever again. Continue this until there is NO movement when the thumb lever is pushed. Next run through the gears in the rear and make sure that it doesn't require excessive effort to switch back into the low gear. If it does back the L limit off a tiny bit and try again. If you can't get the action from the second largest to the largest rear cog light and smooth without the rear D moving once it's in low gear, it's a good indication that it's worn out and should be replaced. I've seen any or all three, bent hanger, sloppy pivots, or L limit adjustment cause your sysmptom. It's more common for a bent hanger or slopped out derailleur, but bad limit adjustment can cause this problem as well.

    Good Dirt
    "I do whatever my Rice Cripsies tell me to!"

  4. #4
    Future Rainbow Jersey
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    Thanks guys!

    Should I go ahead and just get an extra derailleur hanger just in case?

    In the meantime, I'll clean up and adjust it to see if it improves.

    Thanks again!
    "If I can't work to make it...I'll rob to take it..."

  5. #5
    MTBR Demi-God
    Reputation: anirban's Avatar
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    Yes, having a spare derailleur hanger is pretty important on the trail. You never know when you bend it so bad that you might not be able to straighten it! Also, as Squash mentioned- check and make sure that both of your limit screws are properly adjusted.
    "Winners never quit. Quitters never win. But those who never win and never quit are idiots."

  6. #6
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    Couple of tips. Most bike shops keep a simple tool for truing derailleur hangers. The work takes couple of minutes, so if you do some purchase at the shop and use the opportunity to repair the hanger, you likely won't be even charged for it.
    Remember to gear up from the granny gear when you don't need it. The farther the derailleur is from the spokes at descent, the better, you never know what may hit it and cause it enter the spokes - with quite unpleasant outcome.
    Even when the hanger is not bent and the derailleur tuned well, sometimes it happens that the chain falls between cassette and spokes. Particularly at fast descents on FS bike, because of rear wheel hitting rocks and suspension engaging. For the chain not to get stuck if it happens, I use cable fasteners. They are fixed between the spots where spokes cross one another. Unlike the plastic disc coming with bike and serving the same purpose, they don't tend to rub against the cassette and interfere with freewheel working.

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