# Rear Derailleur Hanger...tips on straightening



## Cinelli 82220 (Dec 2, 2010)

My steel bike has a bent hanger, just enough to mess shifting up completely.

Has anyone here ever straightened one? I'd like to try but I don't want to buy the Park tool that I might never use again. And there aren't any shops around here that I can trust to do it either. 

I have lots of non-bike specific tools, would a really big pair of Vise-Grips work? Or a 15" adjustable wrench?


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## xxl (Mar 19, 2002)

Cinelli 82220 said:


> My steel bike has a bent hanger, just enough to mess shifting up completely.
> 
> Has anyone here ever straightened one? I'd like to try but I don't want to buy the Park tool that I might never use again. And there aren't any shops around here that I can trust to do it either.
> 
> I have lots of non-bike specific tools, would a really big pair of Vise-Grips work? Or a 15" adjustable wrench?


I've used a bench vise to good effect (I'm assuming the hanger isn't off by more than a few degrees). You can control things. Never have tried hand tools. Since you're only bending it back with brute force, I wouldn't think you have to have a bike-specific tool.

One thing, though: is the hanger bent in more than one plane? If so, it might be worth having a shop do it for you, so they can trot out their dropout-aligning tools as well as the derailleur alignment gauge. I wouldn't think it'd be much of a charge.


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## wim (Feb 28, 2005)

Cinelli 82220 said:


> I have lots of non-bike specific tools, would a really big pair of Vise-Grips work? Or a 15" adjustable wrench?


Sure, they'd move the hanger into whatever direction you're reefing on those tools. But you'll have no way of knowing if you've straightened the hanger or made matters even worse.

If you're just going by eyesight, you'd be better off to just grab the derailleur body (not the cage!) tightly with both hands and use it as a bending tool (make sure the mounting bolt is very tight in the hanger eye). That way you at least have the derailleur cage, the chain and a cog as a vertical reference line when you look from straight behind the bike.

A field expedient is to remove the derailleur, attach a spare rear wheel by screwing the axle end into the hanger (same thread) and use the spare wheel as a bending tool and as a reference tool by measuring rim-to-rim distances.

But really, bring it to a shop. How can anyone even half-ass competent mess up on this?


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## xxl (Mar 19, 2002)

wim said:


> Sure, they'd move the hanger into whatever direction you're reefing on those tools. But you'll have no way of knowing if you've straightened the hanger or made matters even worse.
> 
> If you're just going by eyesight, you'd be better off to just grab the derailleur body (not the cage!) tightly with both hands and use it as a bending tool (make sure the mounting bolt is very tight in the hanger eye). That way you at least have the derailleur cage, the chain and a cog as a vertical reference line when you look from straight behind the bike.
> 
> ...


That's an interesting field reacharound; never realized the axle thread is the same threading as a hanger.


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## wim (Feb 28, 2005)

xxl said:


> never realized the axle thread is the same threading as a hanger.


Yes, but remember it's true only for the _rear_ axle.


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## xxl (Mar 19, 2002)

wim said:


> Yes, but remember it's true only for the _rear_ axle.


Fortunately, I have _never_ bent my front derailleur hanger.


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## Jay Strongbow (May 8, 2010)

All I have to offer is: be very careful. I'd recommend buying a backup too especially if the cause of that one bending is just use and fatigue.

I broke one recently trying to straighten it. I barely budged the thing before it snapped too. People straighten them no problem all the time and mine was pretty old and wimpy to begin with (by design) but still....be very careful.


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## Cinelli 82220 (Dec 2, 2010)

*Thanks everyone*

It's a steel Ritchey dropout on my DeKerf mountain bike. No way to switch it out. wim, the rear axle idea is genius! Never heard of that before. I have a vise but it's just a little one, not up to this task.

I'm going to take it to a shop and see what they say. It looks like it's only bent in one plane but you never know eh?


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## matfam (Jul 13, 2012)

Making a tool to do this for less than $5.00 is pretty easy if you have access to a drill press. 
Materials needed:
24" 1" square tube
1 10x1 bolt ~1.75" long
2 large fender washers
2 10x1 nuts

Drill a hole in 1 end of the tube and assemble in the following sequence, bolt, washer, tube, washer, nut, nut.

To use your new tool:
1. Place chain on small cog
2. Remove derailleur from hanger
3. Install tool and secure in hanger using the last nut
4. Tighten inner nut to limit axial play in the tube
5. Measure from the wheel brake track to an edge on the tool
6. Oh so gently bend the hanger using the tool to make all measurments the same.


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## kbiker3111 (Nov 7, 2006)

Cinelli 82220 said:


> It looks like it's only bent in one plane but you never know eh?


You never know and thats the problem. Even if its close, it will never shift as well as being perfect. Derailleur hangers are one area where having the right tool makes it work 100x better. 

BTW, the shimano tool is a lot better than the Park straightener.


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## wim (Feb 28, 2005)

Cinelli 82220 said:


> I'm going to take it to a shop and see what they say. It looks like it's only bent in one plane but you never know eh?


True, it might be bent in more than one plane. Should be a 15-minute job, regardless.

As to the comments about snapping a hanger: aluminum hangers are easy to snap on bending them back. But the hanger part on steel dropouts can go back and forth several times without any problems. And as to the vise "not being up to the task:" Even a small vise could easily bend a hanger back. What makes it (and other common hand tools) not up to the task is not lack of leverage, but the lack of a visual reference line or a way to measure for straightness.


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## Jay Strongbow (May 8, 2010)

wim said:


> As to the comments about snapping a hanger: aluminum hangers are easy to snap on bending them back. But the hanger part on steel dropouts can go back and forth several times without any problems.


Mine, that I mentioned snapping, was aluminum. I wouldn't be as worried as much as I probably indicated you should be, Cinelli82220, with yours being steel as wim indicates. In addition to being alloy not steel mine was made to snap easy in order to protect the carbon dropouts/frame.


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## velodog (Sep 26, 2007)

If you're always going to own a steel bike, it's worth having the tool. It don't hurt to check the alignment while giving the bike it's seasonal overhaul.

Otherwise just bring it to a shop and let them do it.


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