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  1. #1
    dedicated beater
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    Derailleur skips/jumps only while on-bike

    So, I periodically go through phases where my rear derailleur jumps out of gear. Being that I just recently replaced the rear triangle on my heckler, and had a new hanger installed and had the setup tuned at the shop, I was hoping I was finally past these troubles. Alas, no, not at all.

    Yesterday while climbing a short steep grade, I had the bike in the small chain ring, and in 2nd gear in the back. Wouldn't you know it, just when I got to the steepest part of the hill, the chain jumped down into 5th gear, nearly sending my knee smashing into the handlebars. Throughout the rest of the ride (which is pretty much flat), the chain would skip a few times here and there, but not really jump out of gear. When I got the bike home and hung up on the stand, it shifted perfectly. What gives? Any advice? Thanks!

  2. #2
    FKA Malibu412
    Reputation: Glide the Clyde's Avatar
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    How old/how many miles on your chain and cassette? Maybe everything has stretched and worn to the point it jumps with a load on as you pedal hard but not with a light load on the stand. It may not be RD adjustment at all.
    "I love the bike. It's my meditation. I think I'm bike-sexual." -Robin Williams

  3. #3
    dedicated beater
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    The cassette is about 2 years old, probably 400 miles and the chain is a year old, about 250 miles.

  4. #4
    psycho cyclo addict
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    If the shop is close by, take it to them and explain what's going on to see what they have to say about it...

    If you decide to swap the chain, keep the old one around just in case, because a new chain on a worn cassette can make matters worse. If the cassette is not dramatically worn, another thing to check is the freehub body (by removing the cassette). Gear slippage can occur when there are significant gouges/bunching where the cassette interlocks with the FH body.

  5. #5
    mtbr member
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    You may also have some ghost-shifting going on due to the suspension movement. It causes flex in the middle segment of cable housing, which can change the cable path enough to cause this problem sometimes. This is one reason I try to give rear-suspension bikes a final shifting test while actually riding, assuming I have enough body weight to squat the bike.

    This is a benefit to the 1:1 actuation ratio of SRAM RDs, and Dyna-Sys as well... they don't move as far for a given amount of cable movement, reducing their sensitivity to this problem.

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