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How to fix this bent RD

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How to fix this bent RD

Old 04-19-21, 08:17 PM
  #1  
raria
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How to fix this bent RD

Can I just bend the hanger? Or could that wreck the frame.

First picPic 2
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Old 04-19-21, 08:20 PM
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spelger
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you can try but it is doubtful. if yo attempt to do it do not grab the RD, you will likely just bend the RD. remove RD and remove the hanger from the frame. put the hanger in a vice and use an adjustable spanner to try to bend. you can remove and lay flat on a peice of glass to see how flat you made it, or how worse it has gotten.

or just buy a new one and a spare.
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Old 04-19-21, 08:20 PM
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I mean just bend it if you ruin the derailleur guess what they are cheap in every sense of the word. You can just throw a new one on and start over for $10-20 or so. If the hanger is bent take that to your local bike shop and let them use the proper tools to attempt to straighten it but it looks more like the RD is bent.
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Old 04-20-21, 04:13 AM
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Take the derailer off the bike; unclamp the cable, take out the pulleys, rip it off.

Turn the wheel back to front and clamp it in the dropout. Now take a shifter and bust out the eyecrometer on that bent hanger. There's a tool to do this accurately, but you shouldn't need it for a 7 speed.

Remove the mounting bolt from the derailer, and pop the part where it mounts into a vice. Now reef on it until it lines up parallel with the cage.
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Old 04-23-21, 09:29 AM
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The derailleur looks straight, but the hanger is bent. Take it to a shop and and spend $15 to have them straighten it with the proper tool.
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Old 04-23-21, 11:26 AM
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Please correct me if I'm wrong but my impression is that these derailleur hangers are meant to be straightened in place. How else are you supposed to align them to know if they are properly positioned?

Yes, I supposed if the hanger is really whacked it wouldn't hurt to first flatten it in a vice. But final alignment has to be done on the bike - even if you get a new one, there's no guarantee that it will go on perfectly aligned.

This particular hanger is bent pretty badly and it might not survive being bent back. A new one might be in order. For minor tweaks, just bend it back.
​​​​​​
As long as the wheel is securely clamped in the dropouts, there is very little chance of wrecking your frame.

Again, please correct me if I'm off base here.

Joe R.
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Old 04-23-21, 01:17 PM
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you align it on the bike frame with something like this:

https://www.amazon.com/CycloSpirit-D...dDbGljaz10cnVl

or a homemade one, something like this:


i have used neither, i've only done what i mentioned earlier and ended up just replacing, easier and works for sure. just don't grab the RD. you are only asking for trouble.
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Old 04-23-21, 02:11 PM
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Originally Posted by Kimmo View Post
... bust out the eyecrometer on that bent hanger....
Thanks for the new word--I've been doing things "close enough" for decades and never heard that one. A long time ago my framing crew boss was telling me to work faster--"This ain't no Steinway we're building here."

Very seldom I'll remove a severely bent hanger from a bike and blacksmith it on the vise anvil, then fine-tune it on the bike. I've never had one break that way. I think impact applies less deformation than bending.

Once when I had no other tools I used a 3' long piece of pipe as a straight edge on the hanger, bike lying flat, and measured to the rim.
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Old 04-23-21, 09:15 PM
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Originally Posted by raria View Post
Can I just bend the hanger? Or could that wreck the frame.

First picPic 2
This is a fairly easy fix. The hanger attached to the frame isnít bent. The derailer itself is bent. You can see the bend in the picture below (red arrow)




The flat steel plate of the Tourney is easy to bend. You can just grab the rear derailer and bend it back into place without damaging the rest of the bike. Be forewarned that the Tourney is a bad unit and is easy to bend. Youíll be better off if you just replace it with a derailer that has a cast aluminum body instead of a stamped steel one. Altus or Acera would be a more durable choice.
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Old 04-25-21, 11:05 AM
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I'm not a fan of trying to straighten derailleur hangers with the derailleur removed. That hole is the weakest place on the hanger and, if you ovalize it, I don't know of a way to fix that.
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