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Thread: Bent Hanger?

  1. #1
    No one carries the DogBoy
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    Bent Hanger?

    My bike has been shifting funny, and recently has started making grumbling noises when pedaling. I took it to the shop and they said the hanger was bent and straightened it. In doing so he said not to have it straightened again, and if I do have it replaced, to only do it once.

    Is he trying to get me to buy another bike, or just giving me advice on the cautious end. I understand not bending it straight again...as it could weaken. I don't understand the only replace it once. Is this because it can strip the threads on the frame or what's the deal with that?

    I don't think it will be a problem, I'm just curious if he was shooting straight with me. In the past his advice has been spot on, but the shop was too busy for me to inquire as to why.

  2. #2
    cyclist/gearhead/cycli... moxfyre's Avatar
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    Quote Originally Posted by DogBoy
    My bike has been shifting funny, and recently has started making grumbling noises when pedaling. I took it to the shop and they said the hanger was bent and straightened it. In doing so he said not to have it straightened again, and if I do have it replaced, to only do it once.

    Is he trying to get me to buy another bike, or just giving me advice on the cautious end. I understand not bending it straight again...as it could weaken. I don't understand the only replace it once. Is this because it can strip the threads on the frame or what's the deal with that?

    I don't think it will be a problem, I'm just curious if he was shooting straight with me. In the past his advice has been spot on, but the shop was too busy for me to inquire as to why.
    Steel bikes typically don't have replaceable derailer hangers, because steel can be bent bake into shape many times.

    Aluminum, however, can't be bent back into shape without severely weakening it. For this reason, good aluminum bikes always have replaceable derailer hangers. Furthermore, the derailer hangers are *intentionally* made to be very weak, so that the derailer hanger bends itself easily and doesn't take the dropout with it.

    Your mechanic is correct. Some might not even try to straighten the hanger once. An aluminum hanger that has been bent and rebent is likely very weak, and should be replaced. They're usually about $20-30.

    By the way, do you know what's causing the hanger to get bent?
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  3. #3
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    The only reason I could think of the shop guy saying not to replace it more than once is that if you're bending a lot of hangers something else could be seriously wrong one way or another... The hanger is meant to break to save the frame, and it's doing it's job. I'd go as far as to say not to unbend the hanger's though, unless you know what you're doing as it takes a little bit of practice and the prospect of breaking it is there... if you insist on doing it, have a spare...

  4. #4
    Senior Member Retro Grouch's Avatar
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    Quote Originally Posted by moxfyre
    good aluminum bikes always have replaceable derailer hangers.
    Try telling that to Gary Klein.

  5. #5
    so much for physics humble_biker's Avatar
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    Nice one Retro Grouch. Had a Fisher in 1992. Damn good bike if you didn't need a rear brake.
    A multi speed bike isn't worth anything with a bent or broken derailleur hanger right? So if it's bent and you still want to ride you have to straighten it. In 15 years as a mechanic I never saw one hanger steel or alloy brake in the hands of a mech. The trouble is you can almost always straighten them but each time you do it weakens it that much more. Sort of like twisting the head off a plastic amry man. My HO is to ride it until you can't ride it anymore or breaks for good or is too annoying to ride.
    If it is an alloy w/replaceable it can still be straightened just not like a solid drop-out and is ill advised because you run the risk of damaging the frame. However as most replaceables are melt cast alloy anymore and not cnc'ed it's best to fork over the (over priced) $20 and start from scratch. And remember only crash on the LEFT SIDE!

  6. #6
    cyclist/gearhead/cycli... moxfyre's Avatar
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    Quote Originally Posted by Retro Grouch
    Try telling that to Gary Klein.
    Klein bikes don't have removable hangers? Why not?
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  7. #7
    Senior Member Retro Grouch's Avatar
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    Quote Originally Posted by moxfyre
    Klein bikes don't have removable hangers? Why not?
    If my memory serves me right, Gary Klein feels that precision alignment, beyond what is possible using separate bolt-on hangers, is important.

  8. #8
    cyclist/gearhead/cycli... moxfyre's Avatar
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    Quote Originally Posted by Retro Grouch
    If my memory serves me right, Gary Klein feels that precision alignment, beyond what is possible using separate bolt-on hangers, is important.
    I guess he also feels that it's important that you buy a new frame now and then

    How far off can a well-aligned hanger be? A few 1/1000s of an inch? Hardly enough to affect indexed shifting in my experience...
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  9. #9
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    [QUOTE=moxfyre]Klein bikes don't have removable hangers? Why not?[/QUOTE

    Neither did the first generation cannondales.

  10. #10
    B-b-b-b-b-b-bicicle Rider orange leader's Avatar
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    Just a thought, but perhaps the mechanic simply meant that if you replace the hanger, and bend it again, to only straighten that "new" one once.

    But I see no reason not to keep replacing the hangers, so long as the rest of the frame is still worth it (not yet destroyed by crashing).

    you may want to keep your drive side on the outside of the bike rack to prevent other people from mashing your derailleur (and hanger). But if it's getting bent from riding off road, then just enjoy the ride, sounds like your having fun, like the bike (and derailleur hanger) was made for.
    Rudimentum mendum menda
    Iudicium mendiosus
    Judicium per erratum
    Judicium et erratum!

  11. #11
    Senior Member Retro Grouch's Avatar
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    Quote Originally Posted by moxfyre
    I guess he also feels that it's important that you buy a new frame now and then

    How far off can a well-aligned hanger be? A few 1/1000s of an inch? Hardly enough to affect indexed shifting in my experience...
    Well, on the other hand, the world has copied some of his bike frame design ideas. I haven't noticed many moxfyre bikes.

  12. #12
    cyclist/gearhead/cycli... moxfyre's Avatar
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    Quote Originally Posted by Retro Grouch
    Well, on the other hand, the world has copied some of his bike frame design ideas. I haven't noticed many moxfyre bikes.
    Indeed! Most moxfyre bikes shun publicity... preferring to hide in my basement or go for a relaxing stroll around DC.

    Quote Originally Posted by dcullen
    Neither did the first generation cannondales.
    My 1990 Trek doesn't have a removable hanger either... but it's very slightly bent and this causes me a bit of trouble adjusting the derailer. I guess most aluminum framebuilders decided after a couple years that removable hangers would be a good idea.
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  13. #13
    ride, paint, ride simplify's Avatar
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    Quote Originally Posted by Retro Grouch
    I haven't noticed many moxfyre bikes.
    They don't call him Retro Grouch for nuthin'!

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