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Bent derailleur hanger

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Bent derailleur hanger

Old 10-13-12, 05:43 PM
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Bent derailleur hanger

I bought a Raleigh Alyeska with a severely bent derailleur hanger. I tried to straighten it myself, but could not get it shifting right. Ended up taking it to the LBS. The Mechanic who helped me said the hanger is "very soft" and would easily bend again. He also said it would probably break if it has to be straightened again.

Does this sound reasonable. I thought forged dropouts were more resilient then that.
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Old 10-13-12, 05:49 PM
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I wouldn't call it soft but yes, if it bent once it bends easier the second time around. Did you or the mechanic heat the hanger? How bad was it bent?
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Old 10-13-12, 06:00 PM
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Originally Posted by Bianchigirll
I wouldn't call it soft but yes, if it bent once it bends easier the second time around.
I should think just the opposite, c.f. "work hardening." But re-working the metal will make it more brittle and likely to fail.
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Old 10-13-12, 06:25 PM
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Originally Posted by Bianchigirll
I wouldn't call it soft but yes, if it bent once it bends easier the second time around. Did you or the mechanic heat the hanger? How bad was it bent?

There was no heat involved. The hanger was bent 60 degrees, maybe more.

The frame has vertical dropouts, can't even use as a single speed. Guess I'm sol.
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Old 10-13-12, 07:09 PM
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you can always get the dropout replaced.
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Old 10-13-12, 07:12 PM
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May be worth trying to straighten it with the right tool. If it breaks, then replace it. Especially if you cannot use it in the current condition.
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Old 10-13-12, 07:19 PM
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Originally Posted by Ciufalon
May be worth trying to straighten it with the right tool. If it breaks, then replace it. Especially if you cannot use it in the current condition.


The bike shop straightened the hanger. I planned on selling it, but I won't sell a bike with a potential problem.

Last edited by brian3069; 10-15-12 at 02:03 PM.
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Old 10-13-12, 07:22 PM
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There is a special tool designed to align the DR hanger. I've watched the local frame maker use one a number of times. He appears to be referencing the butt end of the tool in respect to the frame, but I don't understand how or what — or why except that he is straightening the hanger without any apparent fear of breaking it off. The last one he did for my was on a Gazelle. The hanger looked OK to me, but I asked him to look at it anyway. As it turned out, it was pretty much out of alignment. I think that it was Sheldon Brown who wrote that any bike that had been around for a while was pretty sure to have its hanger out of alignment.

As an aside ... I wish I could afford all the tools needed to service a frame — as well the knowledge to use them. I feel very lucky to live close to a craftsman for whom building frames and servicing them is a trade as well as an art.
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Old 10-13-12, 07:26 PM
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All else fails - https://www.amazon.com/Sunrace-Index-...ailleur+hanger
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Old 10-14-12, 02:53 AM
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I've traightened lots 15+ bent derailleur hangers over the years.All I have ever used is a BIG crescent wrench,the key is just go SLOWLY.Did'nt have any problems with any of them after straightening.Thats why I LOVE STEEL
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Old 10-14-12, 06:00 AM
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https://www.parktool.com/product/dera...nt-gauge-dag-2

I use this tool from Park Tools to straighten bent derailleur hangers. Older bikes may not have replaceable hangers.
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Old 10-14-12, 06:31 AM
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Unfortunatley, this mechanic speaks the truth. A 60 degree bend is substantial. Bending it back, rarely occurs with just one turn of the tool, usually there is some fine tuning after getting it close to perfect. Also, it could have been bent in two directions making it more difficult. If it were my bike, I'd ride it after being fixed, several times. If it shifts fine after a month or two of riding, I'd sell the bike, disclosing that the hanger was straigtend. If it's "soft", i.e. too damaged to hold the derailer properly, you'll know within a month of riding.
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Old 10-14-12, 06:52 AM
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Originally Posted by roccobike
Unfortunatley, this mechanic speaks the truth. A 60 degree bend is substantial. Bending it back, rarely occurs with just one turn of the tool, usually there is some fine tuning after getting it close to perfect. Also, it could have been bent in two directions making it more difficult. If it were my bike, I'd ride it after being fixed, several times. If it shifts fine after a month or two of riding, I'd sell the bike, disclosing that the hanger was straigtend. If it's "soft", i.e. too damaged to hold the derailer properly, you'll know within a month of riding.

Trying to straighten it myself before taking it to the shop probably didn't help matters.

Thanks.

Last edited by brian3069; 10-14-12 at 07:03 AM.
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Old 10-14-12, 10:14 AM
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Dropouts are made from malleable steel for just this reason, so they can bend a reasonable amount without breaking and be realigned. Will it break next time? Possibly. The biggest factors are the sharpness and degree of the bend. As these factors increase, so does the proabability of forming a crease, which causes a stress riser. The risk of future failure druring subsequent cold setting increases proportionally with the severity of the crease.

Dropouts can withstand mutiple small and gradual bends with out failure. I've serviced bicycles where the derailleur hanger has been realigned probably half a dozen times. Kids with X-Mart bicycles are constantly dropping their bicycles on the drive side, which bends the hangers and throws off the indexing. You tell them not to do it, but the bicycle comes back again with the same issue. It typically takes several visits, mounting costs and, most importantly, the increasingly irrate parent, for the message to sink in. This is one of the most common bicycle repairs.

The bottom line is that, having seen the actual bend, your mechanic is the best qualified to assess the risk of failure during a subsequent cold set. If you're fond of the frame and concerned of the risk, you could always install a derailleur guard, which would take the brunt of future accidental impacts and substantially decrease the risk to the hanger.
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