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  1. #1
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    Drivetrain Issues After Broken Derailleur Hanger

    I recently snapped my rear derailleur hanger after landing a medium sized jump. I replaced the part today (after JUST getting my bike back from a tune-up) and am having shifting issues now.

    My first assumption was that the old hanger was bent and the bike was tuned up to suit the bent hanger. With the new hanger that should be straight my rear derailleur will over shift going into the biggest cog if I trim it all the way past 1 on the shifter when before it would do nothing. It also will not go into the smallest cog (7).

    After doing some reading I adjusted the barrel adjuster to try to remedy the situation and started noticing in my smallest crank the chain has WAY too much slack and is making a loud noise from the rear cogs. I am unaware when this started happening, obviously after the hanger snap.

    This bike has been in and out of the shop for the last few months for tune ups, bottom bracket replacements, rear cassette replacement, and more tune ups. It's getting a little frustrating fixing one thing and having another thing break or need adjusted.

    What am I doing wrong?
    Last edited by lnorton89; 06-15-2010 at 07:50 PM.

  2. #2
    Nouveau Retrogrouch SuperModerator
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    Quote Originally Posted by lnorton89
    I recently snapped my rear derailleur hanger after landing a medium sized jump. I replaced the part today (after JUST getting my bike back from a tune-up) and am having shifting issues now.

    My first assumption was that the old hanger was bent and the bike was tuned up to suit the bent hanger. With the new hanger that should be straight my rear derailleur will over shift going into the biggest cog if I trim it all the way past 1 on the shifter when before it would do nothing. It also will not go into the smallest cog (7).

    After doing some reading I adjusted the barrel adjuster to try to remedy the situation and started noticing in my smallest crank the chain has WAY too much slack and is making a loud noise from the rear cogs. I am unaware when this started happening, obviously after the hanger snap.

    This bike has been in and out of the shop for the last few months for tune ups, bottom bracket replacements, rear cassette replacement, and more tune ups. It's getting a little frustrating fixing one thing and having another thing break or need adjusted.

    What am I doing wrong?
    The new hanger is probably still misaligned. Have the LBS check it.

    Then you need to adjust the high and low limit screws, not the barrel adjuster. Well, now you need to do the barrel adjuster, too
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  3. #3
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    Okay thanks for the quick help, hopefully this will be its last trip to the shop for a good while.

  4. #4
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    Quote Originally Posted by lnorton89
    I recently snapped my rear derailleur hanger after landing a medium sized jump. I replaced the part today (after JUST getting my bike back from a tune-up) and am having shifting issues now.

    My first assumption was that the old hanger was bent and the bike was tuned up to suit the bent hanger. With the new hanger that should be straight my rear derailleur will over shift going into the biggest cog if I trim it all the way past 1 on the shifter when before it would do nothing. It also will not go into the smallest cog (7).

    After doing some reading I adjusted the barrel adjuster to try to remedy the situation and started noticing in my smallest crank the chain has WAY too much slack and is making a loud noise from the rear cogs. I am unaware when this started happening, obviously after the hanger snap.

    This bike has been in and out of the shop for the last few months for tune ups, bottom bracket replacements, rear cassette replacement, and more tune ups. It's getting a little frustrating fixing one thing and having another thing break or need adjusted.

    What am I doing wrong?
    start over from scratch
    first off you may still have a bent hanger or you may have bent the deraillier or frame
    the Park deraillier alaignment tool can check this. but lets assume its all straight

    shift into the smallest rear cog and largest front gear
    loosen the cable bolt
    adjust the barrell adjuster all the way in, then out 1 full turn
    adjust the limit screw
    tighten the cable bolt
    shift all the way to the biggest cog/ smallest gear
    adjust the other limit screw
    all adjustment from here should be with the barrell adjuster
    cross chain ( big to small) adjust the barrel if chain is rubbing side of deraillier cage
    reverse cross chain and repeat untill as quiet as can be got

  5. #5
    fuggansonofahowa
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    Quote Originally Posted by dan0
    start over from scratch
    first off you may still have a bent hanger or you may have bent the deraillier or frame
    ......................
    My vote.....

    I have broken and bent many-a-hanger. Most often with a break, there is colladeral damage like a twisted cage. It takes a pretty good force to break a hanger.

    I have Sram X.9 - long and medium cages, and just bend it back into shape with channel locks. Not very scientific, but effective.

  6. #6
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    Okay heres the deal. I took it to one shop and they said I've damaged my derailleur and didn't have any in stock. So I went to my regular shop and he said no it wasn't broken and that I had reinstalled it wrong (not turn backwards enough) so it didn't have the clearance to clear the cogs.

    Rode like a champ all day today and came home to do some test jumps in my back yard off of a 3 ft wooden ramp. After about 10 jumps I landed the last one and broke the hanger...again!

    My question is why am I breaking hangers daily? Am landing wrong or is there something wrong with my bike?

  7. #7
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    if youre not hitting the deraillier or hanger then possibly the chain is too short

  8. #8
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    Quote Originally Posted by lnorton89
    Okay heres the deal. I took it to one shop and they said I've damaged my derailleur and didn't have any in stock. So I went to my regular shop and he said no it wasn't broken and that I had reinstalled it wrong (not turn backwards enough) so it didn't have the clearance to clear the cogs.

    Rode like a champ all day today and came home to do some test jumps in my back yard off of a 3 ft wooden ramp. After about 10 jumps I landed the last one and broke the hanger...again!

    My question is why am I breaking hangers daily? Am landing wrong or is there something wrong with my bike?
    If it is happening on landings, I would highly suspect the chain is too short, especially if you are in the big-big gear combo.
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  9. #9
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    I was in biggest up front and 2 or 3 in back (7 cog cassette). My chain was installed by a LBS who is a Trek dealer. I would HOPE he would know how many links to install. Should I ask him about it or just install another link after I get the new hanger?

  10. #10
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    Quote Originally Posted by lnorton89
    I was in biggest up front and 2 or 3 in back (7 cog cassette). My chain was installed by a LBS who is a Trek dealer. I would HOPE he would know how many links to install. Should I ask him about it or just install another link after I get the new hanger?

    I would check using the big big method
    run your chain around the big front ring and big cassette cog (no dérailleur) and add 2 links
    to be safe you could unhook the shock and put the frame at maximum compression first

  11. #11
    Nouveau Retrogrouch SuperModerator
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    Quote Originally Posted by lnorton89
    I was in biggest up front and 2 or 3 in back (7 cog cassette). My chain was installed by a LBS who is a Trek dealer. I would HOPE he would know how many links to install. Should I ask him about it or just install another link after I get the new hanger?
    Is "2 or 3" the bigger cogs or the smaller ones? There is no standard for the numbering order. "Big" and "small" avoids the confusion.

    And to clarify further, is this a suspension frame or a hardtail?
    mtbtires.com
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  12. #12
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    I checked my chain length and it is at least 2" more than big-big when bypassing derailleur. I hopped a parking curb today and broke another brand new hanger. I was in big up front and probably 2-3 smallest in back. It is a Trek 4300 hardtail. Am saving for a new gary fisher but needs to ride this until then.

  13. #13
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    Quote Originally Posted by lnorton89
    I checked my chain length and it is at least 2" more than big-big when bypassing derailleur. I hopped a parking curb today and broke another brand new hanger. I was in big up front and probably 2-3 smallest in back. It is a Trek 4300 hardtail. Am saving for a new gary fisher but needs to ride this until then.
    hmm
    hard tail means no suspension flex, 2" should be enough
    you sure you're not smacking it

  14. #14
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    Smacking it, like landing harder than normal? I wouldn't think from 6 inches high it mattered...I'm 150lbs.

  15. #15
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    Quote Originally Posted by lnorton89
    Smacking it, like landing harder than normal? I wouldn't think from 6 inches high it mattered...I'm 150lbs.
    no, like hitting the deraillier

    maybe have someone watch closely while you do it, see what is going on when you land

    check the frame for cracks around the welds

  16. #16
    fuggansonofahowa
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    Derailleur hangers just don't break landing off a curb....obviously, something else is happening here. Does the derailleur get caught up in the wheel, or is it just hanging there when this occurs? Is the drop out twisted and broken, or just snapped in half?

    Posting pictures may help diagnose this strange problem.

  17. #17
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    The first one or two had a little bend before breaking the last two just snapped. I will try to take some pictures with a good camera tomorrow in the daytime and upload. My LBS is stumped as well as to the cause.

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