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Do you straighten mech hanger on bike?

3wheeler3wheeler Posts: 110
edited May 2018 in Workshop
I used the park tool to check and straighten my mech hanger, but when I was searching for the correct replacement hanger I came across a discussion where someone was advising never to straighten a mech hanger attached to a frame, apparently you can damage the frame!

Anyone heard of this happening? What do professional mechanics do? I understand you can just replace instead of straighten but there's no guarantee the new hanger will be perfectly aligned when it's attached to your frame.

Posts

  • veronese68veronese68 Posts: 25,978 Lives Here
    I've always done it on a frame. How else are you supposed to use the tool?
    Don't be brutal with it. Check alignment in more than one place, use the same spot on the wheel so as to remove any discrepancies if the wheel is out of true. Tweak it gently using the tool as a lever, check again and adjust again if necessary. Try to avoid going too far then having to bend it back again.
    If you can break a frame doing that I suspect there is a problem with the frame.
  • fenixfenix Posts: 5,437
    If mines ever taken a knock I've just bent it gently - never had a problem but it's never been that bent.
  • svettysvetty Posts: 1,904
    It isn't possible to align a hanger off the bike.

    Just make sure the tool is screwed into the hanger correctly, that the hanger is properly screwed on and tightened and that the rear wheel is properly in the drop-outs with the skewer fully tightened.
    FFS! Harden up and grow a pair :D
  • keef66keef66 Posts: 13,123
    Svetty wrote:
    It isn't possible to align a hanger off the bike.

    Just make sure the tool is screwed into the hanger correctly, that the hanger is properly screwed on and tightened and that the rear wheel is properly in the drop-outs with the skewer fully tightened.

    ^wot they all said. My carbon bike fell over in the garage and bent the hanger. I just ordered a replacement and fitted that, checking afterwards using the tool. I've kept the bent one as a spare in case the hanger ever breaks completely, but I can't tell it's bent just by looking at it. And there'd be no way of checking or straightening it off the bike.
  • svettysvetty Posts: 1,904
    keef66 wrote:
    Svetty wrote:
    It isn't possible to align a hanger off the bike.

    Just make sure the tool is screwed into the hanger correctly, that the hanger is properly screwed on and tightened and that the rear wheel is properly in the drop-outs with the skewer fully tightened.

    ^wot they all said. My carbon bike fell over in the garage and bent the hanger. I just ordered a replacement and fitted that, checking afterwards using the tool. I've kept the bent one as a spare in case the hanger ever breaks completely, but I can't tell it's bent just by looking at it. And there'd be no way of checking or straightening it off the bike.

    I always align spare hangers (on the bike obvs) so that if I later need to fit it I know it's going to be straight.
    .
    FFS! Harden up and grow a pair :D
  • 3wheeler3wheeler Posts: 110
    Thanks all. Good to hear there's no need for alarm.
  • Vino'sGhostVino'sGhost Posts: 4,129
    3wheeler wrote:
    Thanks all. Good to hear there's no need for alarm.

    Ha it’s going to be alright :)

    Just to add a small comment, the hanger is adjusted relative to the the frame it sits on so must be adjusted in situ.

    They are intended to break or bend sacrificialy to protect the frame in the event of impact/crash etc. Because of this they tend through necessity to be relatively delicate compared to the frame. Obviously they need to retain a level of stiffness to permit crisp accurate shifting under load and so the bar used to bend them is long and can look quite industrial.

    Most replacement hangers should be about right straight out of the packet if the thought of hanger alignment is daunting .
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