Please Tell me This is Fixable: Beant RD Hanger
05-19-11, 04:13 PM
#1
Tiocfáidh ár Lá
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Please Tell me This is Fixable: Beant RD Hanger
I was coming home today and my chain dropped off the small ring onto the BB shell, the inside. It happened earlier too so I'm thinking I need a simple adjustment. So I go to kick it back up onto the chain rings as I am rolling, just like I did before and the next thing happens is the rear derailleur goes into the spokes and disaster strikes. 
It looks really bent but I don't know what the properties of Titanium are like. I hope it can be bent back.
It looks really bent but I don't know what the properties of Titanium are like. I hope it can be bent back.
05-19-11, 04:33 PM
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From what I've read, titanium is very difficult to bend as it takes enormous amounts for force to re-shape it.
If you want to try to do it yourself, you'll want to follow these instructions. You'll probably need the derailleur hanger alignment gauge and the frame-fork alignment gauge.
Edit: I forgot to mention that this happened to me with a steel frame bike and I was able to get it fixed at the LBS.
If you want to try to do it yourself, you'll want to follow these instructions. You'll probably need the derailleur hanger alignment gauge and the frame-fork alignment gauge.
Edit: I forgot to mention that this happened to me with a steel frame bike and I was able to get it fixed at the LBS.
Last edited by ElMono; 05-19-11 at 04:57 PM. Reason: additional info
05-19-11, 04:51 PM
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Take it to your LBS, they should have Park Tool DAG-2, should take about 5 mins to fix that, at least that how long it took my LBS to fix mine on Monday, Lynskey built Ti frame, with an almost identical hanger bend due to a 7800 rear derailleur snapping in half.
05-19-11, 10:22 PM
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Is the dropout also Ti?
05-19-11, 10:32 PM
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The good news is, Ti has a practically infinite fatigue life IIRC, so your hanger shouldn't be any weaker when it's fixed.
05-20-11, 06:35 AM
#6
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YEah the hanger is also Ti. Well ok I'll take her to the shop today maybe I just think it looks worse then it is. There are no cracks so that is obviously good. This is a fix I would definitely not do my self.
05-20-11, 11:03 PM
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I'd be game, but I'd want to clamp a bare hub in there and cut a derailleur mounting bolt to fill the hanger hole (ideally a nice flat-headed bolt and nut clamping it would be best), then I'd need an alignment tool.
The high fatigue life implies Ti doesn't really work harden, which is the phenomena that makes bent stuff hard to bend back to its original shape; I'm pretty sure that's what makes aluminium unfixable like this. The biggest risk with these repairs is usually deforming the threaded hole and the small area of mounting face around it.
The high fatigue life implies Ti doesn't really work harden, which is the phenomena that makes bent stuff hard to bend back to its original shape; I'm pretty sure that's what makes aluminium unfixable like this. The biggest risk with these repairs is usually deforming the threaded hole and the small area of mounting face around it.
Last edited by Kimmo; 05-20-11 at 11:15 PM.
05-20-11, 11:07 PM
#8
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That is really bent but the reason it does not have a removable hangar is because it can be bent back into alignment just as a steel dropout can be bent back.
Should be a 5 minute job at the right shop.
Should be a 5 minute job at the right shop.
05-21-11, 08:34 AM
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Not exactly. Titanium (and steel) can be repeatedly subjected to a certain amount of stress practically forever without failing. I am not sure what amount of stress this is, although it is definitely much less than the stress required to go into plastic deformation, as the OP's hanger has. FWIW, bending like that is failure, and repeatedly bending it back and forth will eventually cause it to snap off... but bending it back a couple of times over the course of the bike's life isn't a problem.
05-21-11, 09:04 PM
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Ah, that makes a bit more sense.
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