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I crashed it, and now the rear derailleur is not shifting right, it's clicking alot

Rear Derailleur

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    I have more pictures from different angles. I'm wondering if I need to get a new rear derailleur
    – Shane Hartley
    Commented Apr 6 at 16:29
  • could be a new RD is needed, but at the same time if the hanger is bent even a little, just replacing the RD may not be enough. I'd undo the big nut holding the derailleur to hanger, and then use pliers to make sure that's straight, and then reassemble.
    – Criggie ♦
    Commented Apr 6 at 23:58
  • We need it only from one angle ;-).
    – Peter - Reinstate Monica
    Commented Apr 8 at 0:15
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    Please post more pictures, preferrably taken from a larger distance, and with the camera pointing exactly parallel to the main "plane" of the bicycle, i.e. the direction in which it moves. This will hopefully show whether the derailleur and derailleur cage are parallel to the main plane, as they should be. I'd say the derailleur cage does look bent in this photo, but that may be a distortion created by the too-close perspective.
    – jcsahnwaldt Reinstate Monica
    Commented Apr 9 at 1:43
  • I offroad bicycle a lot. I also replace derailleurs a lot. The single most replaced component for me.
    – hanshenrik
    Commented Apr 9 at 11:23

6 Answers 6

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Looks bent to me (but camera angles are deceptive). The hanger is usually the bit that bends first, although derailleurs can get damaged. You LBS will have tool to check and straighten the hanger, although they can be jury-rigged by a DIYer if you prefer using eyeballs and adjustable spanners for repair, I have always found it unsatisfactory without the correct tool. A cheap one can be purchased for as low $30, but it not a tool you use often.

Your bike has a replaceable hanger, but I would never rely on a replacement being straight without running the tool over it. Straigtening a bent hanger does risk breaking it, so if you need the bike, it is not something to do without having a spare on hand (or you do it very carefully).

Once you have straightened the hanger, then look at the derailleur. While bent derailleurs are sometimes repairable, they are rarely the same. It is often quicker and easier to just replace. If you paying you LBS to do the work, a new replacement is usually cheaper that repair.

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  • "They are rarely the same" is my experience as well. Maybe because the hinges acquire some undesired play by the back-and-forth-bending, maybe because the result is never perfect -- but yes, they are not precise any more. (But still usable, mind you.)
    – Peter - Reinstate Monica
    Commented Apr 8 at 0:20
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Typically derailleurs don't get bent that easily. Derailleur hangers (i.e. the part on the frame where the derailleur is screwed to) do. The good news is, on modern bikes they typically are easily exchangeable since they are thought as a predetermined breaking (or in this case: bending) point. Therefore they are built in a way to protect the frame and derailleur from damage which would be much more costly.

If I get your photo right, your bike has a replaceable derailleur hanger (the matte black part between derailleur and frame) and it looks bent. So my first step would be to get a replacement. In most cases this should already fix your problem. Only if this does not do the trick, I would try to replace the derailleur itself.

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    I think everybody else disagrees with the "typically derailleurs don't get bent" part. In my experience the cage is the weakest part and bends easily.
    – Peter - Reinstate Monica
    Commented Apr 8 at 0:22
  • @Peter-ReinstateMonica since a derailleur has several joints that allow it to some degree to give way to an impacting force, bending a derailleur would require to pinch and twist it in a direction that cannot be compensated by the joints. This is not the type of impact you get in a typical bicycle crash even if you're not on smooth tarmac.
    – Benedikt Bauer
    Commented Apr 8 at 4:51
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    Anyone who has worked in a bicycle shop knows that derailleurs get bent all the time. All it takes is an impact from the side, or something getting stuck in the spokes of the rear wheel. Yes, a derailleur has many joints, but their axles are (more or less) parallel to each other, which means they can only compensate impacts in one plane. Most of the time when the hanger gets bent, so does the derailleur.
    – jcsahnwaldt Reinstate Monica
    Commented Apr 9 at 2:39
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    I downvoted this answer. The claim that derailleurs typically don't get bent is far from true and should be corrected.
    – jcsahnwaldt Reinstate Monica
    Commented Apr 9 at 20:20
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Hanger looks bent to me! Do not ride until fixed: the bent mechanism can go into the spokes with disastrous results! Ask me how I know. This is an easy fix for your LBS, as they have tools to measure and correct the alignment.

I always make sure I have a replacement derailleur hanger for each bicycle I have. When mountain biking, I carry one with me. Their purpose in life is to bend and protect the frame and derailleur.

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    I know this too. And it was on a bike I had borrowed from a friend and I ended up having to get the derailleur hanger welded back, powder coated the whole frame, etc replaced the rear rim and spokes. As poor student it sucked but it wasn't my first wheel rebuild.
    – Jason Harrison
    Commented Apr 8 at 3:30
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Yes its clearly damaged. You want the cage to be in-line with each rear cog.

Given its already bent, your best option is to work out where the bend is, and "unbend" it. The worst that will happen is you'll break the damaged-part and need a replacement.

It could be the derailleur's cage, the mount, the hanger (bit between derailleur and frame) or worst case is its the frame itself.

It is also likely that the bend is distributed across a number of parts, and a bunch of small un-bends will be needed. Good luck! Remember, its already not-working so anything you do to make it better is an improvement.

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    Just to point out: Some modern rear derailleurs (at least Shimano 12 speed ones) have a bent cage on purpose. But it doesn’t look like OP has one of those.
    – Michael
    Commented Apr 8 at 19:46
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Right at first glance I’d say it’s your derailleur hanger that is bent, which in turn is causing your derailleur to sit at the wrong angle, resulting in bad shifts/clicking sounds. They are easy to change and not very expensive. However they are specific to your particular make and model of bike, so be sure to get the right one.

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  • Hi, welcome to bicycles. This is a good answer, but the other 4 answers already say this.
    – DavidW
    Commented Apr 9 at 0:11
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A zero-cost, no-tool, but somewhat brutal way to at least improve (and maybe mostly fix) the shifting in such cases: Put the bike upright, have someone hold it, grab the derailleur cage, make it point straight down, and then simply pull it away from the wheel. I mean, pull in the same direction as the wheel's axle. Bit hard to describe...

You'll need quite a bit of force (I'd say the equivalent of something between 15 to 30 kg, but I'm just guessing here, I never measured it).

Don't be too shy. Don't be too bold either. Some experience with metal parts and how they react to bending is a great help here.

You'll have to bend the whole thing a bit "too far", i.e. until it's slightly bent out of its original (i.e. factory) shape in the opposite direction than before, because it will snap back a little bit.

The theory behind this is that you'll apply the opposite of the force that bent the derailleur and the hanger, and if you also apply it at roughly the same point of impact, this opposite force will distribute along all these moving parts the same way as the original force, bending each one a little bit, but in the opposite direction. Ideally, they all get bent back into their original shape.

Of course, this never works perfectly, but I guess I've done this a hundred times, and it often works quite well. Some joints will probably be a bit looser than originally, but it's hard to tell.

If this was a super light-weight frame with high-end components, I'd be a bit worried, but with a mid-level bike like this, it should be fine. In the worst case, this "brutal" method doesn't help much, and you have to exchange the derailleur and the hanger anyway.

Disadvantage of this method: You only apply a force in the transverse direction (left to right), but when derailleurs / hangers get bent, they're often also a bit "twisted" around the vertical axis. Special tools give you more control.

Here is a nice video showing a version of this method. A good deal more sophisticated and less brutal than what I described. :-)

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