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I think I bent the mech hanger (right term?) on my Schwinn MTB. Now changing gears is hard. I'm trying to better understand my options. What I understand so far as to what I can do:

  • Look for a new mech hanger for this make/model
  • Try un-bend (using force) to correctly align hanger

From my visual inspection, the bend looks slight, yet has a big impact on the gear. A few pics:

Bent mech hanger

Bent mech hanger

I'm biased towards a do-it-yourself solution, if possible. Thank-you.

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    It appears that the hanger's bent, though the derailer may be bent as well. Sometimes you can straighten things by just grasping and bending. If you have a spare skewer-type axle the thread on that is often the thread in the hanger where the derailer bolt fits, so you can use an old axle (with nuts) as a lever to "accurately" bend it back. Or you can use a small adjustable wrench. – Daniel R Hicks Jan 30 '16 at 12:19
  • Park Tools (and others) do a tool which will tell you if the hanger's bent, and will also help you straighten it, Might be worth investing in that if you're going to do it yourself. That's all a shop would do. – PeteH Jan 30 '16 at 13:18
  • Bent hanger can be easily replaced which might be a better option. And they are not that expensive. Even when bent back the angle will almost certainly not be the correct one. – Carel Jan 30 '16 at 14:33
  • Also "hanger too bent" from typing "bent hanger" into the search box – Móż Jan 30 '16 at 21:56
  • Gidday and welcome to SE Bicycles - thank you for including useful and relevant photos in your question. Don't be put off if this question is closed as a duplicate; instead just remember to use the search functionality first, and to pay attention to the suggestions that Stack Exchange lists as you type your question. – Criggie Jan 31 '16 at 3:06
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It looks like both the Hangar and the attachment from the rear mech to the hangar are bent? You could try to straighten yourself with pliers or a small wrench but I would suggest a visit to the LBS who will use a Hangar Alignment Tool

http://www.parktool.com/product/derailleur-hanger-alignment-gauge-dag-2-2?category=Frame%20&%20Fork

With a bent hangar you will never have smooth, crisp shifting at all. That chain needs a degrease by the looks of the first photo. If it's an old chain, it may have "chain stretch" which will also affect shifting and start to ruin your cassette. Ask the LBS to check the chain length as well?

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  • I agree with other points but this hanger is bent beyond the purpose of a derailleur alignment tool, which is designed for fine adjustments. Mech hangers are designed to be replaced in this situation – Bent Spoke Cycle Repair Feb 5 '16 at 22:50
  • This is a poor summary of the accepted answers to the questions of which this is a duplicate. – Móż Feb 6 '16 at 6:32
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Best solution is going to be to replace the hangar and the rear Derailer.

However, you can take the hangar off and use a vise to get it flat. Clean it and the frame around that area to keep dirt from interfering with the attachment. Use blue loctite (formula 242) on the fasteners and a light coating of grease on the flat areas to keep dirt out. For the final alignment, what you want it is the rear derailer jockey pulleys to be perfectly parallel to the cassette/freewheel's cogs. The whole purpose of the rest of the derailer is to keep those jockey pulleys parallel as they move.

Same is true for the rear derailer itself, but it is going to be more fragile than the frame hangar--you can try to straighten the RD, but it looks fairly cheap, and the metal used my be significantly work-hardened by all this bending, so it may break during the straightening attempts.... a replacement shouldn't be more than $10-$15 anyway. The LBS may have a 'pull' or used rear derailer that they can let go for a significant discount that'd still be an upgrade too. (If they don't, they don't... some shops don't allow this sort of sale...) Also, the jockey pulley brackets (that attach it to the parallelogram of the RD) may need to be straightened to be parallel to the RD body... but the majority of re-bending of the RD should be done close to the attachment point of the RD to the hangar, as it should be 'designed' to be adjusted there.

Good luck!

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I assume the mech hanger is aluminium, as normal. Aluminium is much less able to handle fatigue caused by this kind of bending than steel, I would advise strongly against trying to bend it back into shape.

The only reason your bike even has this part is so that you can install a new one cheaply when you damage it in this way. Without it an aluminium frame would be damaged and written off.

It looks as though the frame dropouts have stayed still, but your LBS will have tools to check their alignment if you don't want to buy these. You should check the alignment of the dropouts and source a new hanger. Easily sourced online if you want a DIY solution.

Then you could try installing the derailleur if you determine it is still usable, or buy and install a new one if it seems damaged. It looks bent from here and worth replacing.

Bottom line is you've trashed your derailleur hanger and need to put up some cash. The silver lining is that because of the hanger it is much less expensive than the cost of a new frame.

Hope you're back on the road soon!

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