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Thread: How many times can I (re-)straighten my steel derailleur hanger?

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    Default How many times can I (re-)straighten my steel derailleur hanger?

    I'm pretty sure I know the answer to this based on all the Bike Materials 101 articles about fatigue cycles I've perused, but just want to get a gut-check from the intelligentsia:

    On a steel frame with an integrated non-replaceable RD hanger, is there any limit to the number of times that hanger can get bent and then re-straightened before its performance is compromised or suspect?

    [Corollary question: is there any limit to the amount that hanger can get bent and then re-straightened...? i.e., if it requires a ~20° bend to get back into compliance all is fine, but if it requires a ~90° bend you're SOL?]

    Thanks.
     

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    Default Re: How many times can I (re-)straighten my steel derailleur hanger?

    They definitely start getting softer. Once you bend the hanger enough for it to stay bent, you're beyond the point where you start to lose strength after you bend it back. If you look closely you can see little cracks where it's been straightened. I've had steel bikes from the early '90's that I've bent the derailleur hangers four or five times and there's no paint left on the hanger and it just feels weak when I straighten it now.
     

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    Default Re: How many times can I (re-)straighten my steel derailleur hanger?

    I've never seen one fail apre' vous me putting it right and I've straightened more than I can recall.

    Steel is pretty forgiving.

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    Default Re: How many times can I (re-)straighten my steel derailleur hanger?

    Quote Originally Posted by lumpy View Post
    They definitely start getting softer. Once you bend the hanger enough for it to stay bent, you're beyond the point where you start to lose strength after you bend it back. If you look closely you can see little cracks where it's been straightened. I've had steel bikes from the early '90's that I've bent the derailleur hangers four or five times and there's no paint left on the hanger and it just feels weak when I straighten it now.
    It actually gets harder, you're work hardening it. It also gets more brittle, hence the cracks. If it feels easier to bend, it's because there's enough cracks that you're deforming less material now.

    Eventually it will break. When, I can't say. But plastic deformation again and again will eventually lead to failure.
    Last edited by dgaddis; 04-22-2019 at 02:14 PM.
    Dustin Gaddis
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    Default Re: How many times can I (re-)straighten my steel derailleur hanger?

    Quote Originally Posted by dgaddis View Post
    It actually gets harder, you're work hardening it. It also gets more brittle, hence the cracks.
    That's a useful distinction. Correct atm (layman's) o.
     

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    Default Re: How many times can I (re-)straighten my steel derailleur hanger?

    Quote Originally Posted by Bob Ross View Post
    On a steel frame with an integrated non-replaceable RD hanger, is there any limit to the number of times that hanger can get bent and then re-straightened before its performance is compromised or suspect?
    Same as the number of licks required to get to the center of a Tootsie Pop.

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    Default Re: How many times can I (re-)straighten my steel derailleur hanger?

    Quote Originally Posted by Peter Polack View Post
    Same as the number of licks required to get to the center of a Tootsie Pop.
    iirc that was "three", no? Apparently I came damn close:

    Brought it to the LBS. They made a valiant attempt to straighten the hanger, but eventually conceded defeat; said they weren't comfortable trying to get it any straighter, were concerned they would just damage it further.

    So I sent some photos to the builder (Carl Strong). He said to ship the frame back to him, he wanted to try to straighten it himself. If it turned out it was indeed beyond repair he would whip out the saws and torches and whatnot and install a new rear dropout with integrated hanger.

    Just got a note today from Carl, less than 24 hours after receiving my frame: He was able to straighten the hanger, get it and the dropouts perfectly aligned, no torch necessary. And no charge (except for return shipping)! Now that is a mensch. :::swoon:::
     

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    Default Re: How many times can I (re-)straighten my steel derailleur hanger?

    Quote Originally Posted by Bob Ross View Post
    iirc that was "three", no? Apparently I came damn close:

    Brought it to the LBS. They made a valiant attempt to straighten the hanger, but eventually conceded defeat; said they weren't comfortable trying to get it any straighter, were concerned they would just damage it further.

    So I sent some photos to the builder (Carl Strong). He said to ship the frame back to him, he wanted to try to straighten it himself. If it turned out it was indeed beyond repair he would whip out the saws and torches and whatnot and install a new rear dropout with integrated hanger.

    Just got a note today from Carl, less than 24 hours after receiving my frame: He was able to straighten the hanger, get it and the dropouts perfectly aligned, no torch necessary. And no charge (except for return shipping)! Now that is a mensch. :::swoon:::
    The Effing builder knows what's up.

    My moto has always been bend it till it snaps, you're not going to make it any less usable. If they are really bent, it's a good idea to get them close with something other than a HAG as you're putting all that force through the threads and that's not ideal. Bend it most of the way back with a pliers wrench or an adjustable and then go after it with something precise.

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    Default Re: How many times can I (re-)straighten my steel derailleur hanger?

    Quote Originally Posted by abbeyQ View Post
    If they are really bent, it's a good idea to get them close with something other than a HAG as you're putting all that force through the threads and that's not ideal. Bend it most of the way back with a pliers wrench or an adjustable and then go after it with something precise.
    And run a tap through it after you've bent it most of the way back but before you thread in the hanger adjustment tool. Once you've bent the hanger and then roughly straightened it with channellocks or an adjustable wrench, the hole won't be round anymore.
     

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    Default Re: How many times can I (re-)straighten my steel derailleur hanger?

    Quote Originally Posted by abbeyQ View Post
    If they are really bent, it's a good idea to get them close with something other than a HAG as you're putting all that force through the threads and that's not ideal. Bend it most of the way back with a pliers wrench or an adjustable and then go after it with something precise.
    Jason makes a good point. I'll add this. Our procedure was to clamp the faces of the dropouts using a large adjustable wrench while bending the hanger with another. The force needed to bend the hanger would be enough to also bend the dropout t the rear of the axle slot, especially if the dropout has axle position adjuster screws.

    We also did a fair amount of filling the hanger with brass in order to be able to re-tap the now distorted derailleur mount hole. Of course this would damage the paint. Where paint was important we used the frame saver dropout repair part, but I doubt this would work on modern frames due to the lack of clearance between the frame and cassette.

    Ken
     

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    Default Re: How many times can I (re-)straighten my steel derailleur hanger?

    I'll also add that if I do anything like this there's a dummy axle in the bike

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    Default Re: How many times can I (re-)straighten my steel derailleur hanger?

    Quote Originally Posted by Ken Vogel View Post
    Jason makes a good point. I'll add this. Our procedure was to clamp the faces of the dropouts using a large adjustable wrench while bending the hanger with another. The force needed to bend the hanger would be enough to also bend the dropout t the rear of the axle slot, especially if the dropout has axle position adjuster screws.

    We also did a fair amount of filling the hanger with brass in order to be able to re-tap the now distorted derailleur mount hole. Of course this would damage the paint. Where paint was important we used the frame saver dropout repair part, but I doubt this would work on modern frames due to the lack of clearance between the frame and cassette.

    Ken
    This was before I got a set of those awesome Knipex 250mm Wrench-pliers.
    I didn't take a picture with the Campag dropout-tool in position +two adjustable spanners making the hard work.
    A small propane/butane torch was used to soften up the thing a bit.



    Andrea "Gattonero" Cattolico, head mechanic @Condor Cycles London


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    Default Re: How many times can I (re-)straighten my steel derailleur hanger?

    Gattonero,

    That had a better outcome than I would have expected. I bet bending that put a bit of a pucker in the hiney.

    Cheers
     

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