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Call me a Fred
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Discussion Starter · #1 ·
I think that my derailler hanger is slightly bent. Is there anyway to check the alignment without buying the tool (or having an LBS do it)?
 

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MikeBiker said:
I think that my derailler hanger is slightly bent. Is there anyway to check the alignment without buying the tool (or having an LBS do it)?
Look at it, if it looks crooked, straighten it. Alot of hangers these days are replaceable, if you have one of those they're also usually soft enough to align by hand. Non replaceable hangers are best done with the leverage of the proper tool.
 

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From the past.

I'm not at all sure that this is still possible with a modern bike, but here's an ancient bent hanger field check:

Remove derailleur and front wheel. Remove skewer from front wheel hub. Screw front wheel axle stub into hanger eye (used to be the same thread, but if it no longer is, stop right there and forget this post :) ) Now check rim-to-rim distances between the rear wheel and the cantilevered front wheel all the way around - if they're not the same all the way around, the hanger is bent.

I'm not telling you to use the front wheel as a tool to straighten the hanger, but it has been done :)
 

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Front or back axle?

wim said:
I'm not at all sure that this is still possible with a modern bike, but here's an ancient bent hanger field check:

Remove derailleur and front wheel. Remove skewer from front wheel hub. Screw front wheel axle stub into hanger eye (used to be the same thread, but if it no longer is, stop right there and forget this post :) ) Now check rim-to-rim distances between the rear wheel and the cantilevered front wheel all the way around - if they're not the same all the way around, the hanger is bent.
I think you mean to say use a second rear wheel. Derailleur hanger threads are 10x1mm, which is the same as most rear quick release axles. Front quick release axles are usually 9x1mm threading, so they won't fit the derailleur hanger*

*Note: Campagnolo rear axles are actually 10mm x 26tpi threading, which is close enough that it would work in a pinch.
 

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Bike Dude
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If your talented

you can use a cresent wrenh and slooooooowly bend it back. If your scared go to the LBS to do it right.
 

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Call me a Fred
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Discussion Starter · #6 ·
It's a steel hanger on a steel frame, so I'm not really worried about damaging it. I'll try the wheel method (I have a spare set of wheels).
 

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Mark McM said:
I think you mean to say use a second rear wheel. Derailleur hanger threads are 10x1mm, which is the same as most rear quick release axles. Front quick release axles are usually 9x1mm threading, so they won't fit the derailleur hanger*

*Note: Campagnolo rear axles are actually 10mm x 26tpi threading, which is close enough that it would work in a pinch.

You're absolutely right - thanks for pointing it out. It's been at least 20 years since I've done this. Shimano was just coming up on the horizon as a maker of serious racing stuff . . .
 

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MikeBiker said:
I think that my derailler hanger is slightly bent. Is there anyway to check the alignment without buying the tool (or having an LBS do it)?
You can probably eyeball a 7-speed bike but, as rear cog spacing gets closer, derailleurs get pickier about having the alignment spot-on.

If you're trying to align a derailleur hanger with a crescent wrench, it's good to keep the derailleur bolted onto it. Otherwise you risk ovalizing the derailleur mounting hole.
 
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