TLDR: My mechanic realigned my derailleur and now it looks off and the shifting has issues. He claims it’s alright. Who’s right?
I had a crash which resulted in all sorts of things, but mainly it bent the derailleur hanger and cage. Since I don’t have the tools to bend it back in a way that the shifting is perfect, I took the bike to a mechanic who did great work on setting up my bike way back when I bought it 10k km ago. In the meantime I learned to do basic maintenance myself and even switched groupsets. So I know how a fresh 2×10 GRX looks like. When I came to pick up the bike, the cage line looked off to me. From my memory it should be more straight down. The mechanic told me „You’ve never seen a properly set up cage before.“ I trusted him. Going for a test ride, I noticed first gear didn’t like to stay in first. He did a test ride and he said it’s fine and it will settle itself. Dumb of me not argue it, I left believing him since he did a great job last time out.
In the meantime I did three rides. First gear likes to jump back to second, but it doesn’t quite stay there. And the hardest gear is the real culprit: When doing a quarter backpedal on descends, the chain slips off the chainring. See the last picture. My guess is the chain line is off because of the cage being bend so far outwards. But I’m not sure if the first gear issue comes from the same thing or if it’s a cable tension problem. For this I need to try around a bit more.
Now my question is: Does the angle of the cage look off to you or should it actually look like that? Is it something I can fix or might there be a lasting issue from my crash which could mean that the derailleur is broken?
by honeybagder13
23 Comments
I didn’t read all that, but that shit is not straight
That shit is bent
bendy boy.
That very much doesn’t look right. It should be straight down.
The hanger needs a proper tool to straighten it, though I would expect a mechanic to have one. I think most mechanics would replace the mech but they can be straightened with a fair bit of effort.
It’s pretty obvious when the tool is installed whether it’s straight or not. If you have a community bike shop you might be able to check for yourself, but otherwise they should be able to show you the tool indicating it’s in plane. Otherwise just replace the hanger.
The fact that fastest gear want to go on the second might be normal if he changed the chain/housing. New chain tends to elongate a little bit which will stop the chain jumping outward.
For the slowest gear tho the cage position doesn’t seem normal to me.
Did he changed the derailleur hangeur or not?
Fellow mechanic – It looks off to me, he should use a derailleur hanger alignment tool or just get you a new derailleur hanger for starters, if that doesn’t help perhaps your derailleur is damaged/cage bent. I would try those options first.
If your chain is falling off the front chainring your front derailleur limits are probably too far out/incorrect.
Have you changed your chain at all during this?
It obviously looks bent. I mean, really obviously it looks bent. However, it’s not clear to me if it’s the derailleill hanger or the derailleur.
However, the first thing I would do is make sure that your mechanic used something like Park Tool DAG-3 – Derailleur Hanger Alignment Gauge, You can buy clones off of a variety of different websites if you spend enough time. But virtually every bike shop will have one of these.
Once you know that your dropout is aligned, then you go ahead and you check if your derailler is bent or not.
If he truly is competent, he used the tool. He’s assuming that the dropout is up and down, which it may well be if he actually aligned it with the tool. And then for whatever reason, he just is incapable of seeing that an actual derailer itself can be bent. Most likely, this is just the part that carries your top-to-bottom jockey wheel, but without actually taking a very close look at it and comparing it side by side, it’s really hard to tell from a Reddit picture.
Find another mechanic
1. The hanger looks bent
2. The cage will have a slight bend to it from the factory, that’s normal so maybe you didn’t bend it.
3. I don’t like the cable. The tension screw is almost all the way out. I would suggest a new cable and before installing it I would turn the barrel all the way down, give it 2-3 twists out and the install the housing and the cable
No bueno
It’s very obviously misaligned.
In most crashes, the derailleur hanger gets smashed inward, but the picture shows that it’s bent outward, so he must have pulled it out too much.
What to do now? First, I would have a hard time trusting this mechanic. Second, I would suggest buying a couple of derailleur hangers: one to replace this bent one, and another to keep around as a spare. The reason I suggest getting a new one is that aluminum tends to crack when it gets bent back and forth, and it has already gone through at least one cycle of severe deformation, so it’s no longer as trustworthy as before. (A new hanger should still be aligned using a gauge since neither the hanger nor your frame is perfect, but it might be already good enough out of the box that you can live with it, and it would certainly be better than what you currently have.)
As for how to fairly resolve the unsatisfactory business transaction where you paid the mechanic and he inflicted unnecessary overcorrection and tried to gaslight you, I can’t say.
You need a better mechanic.
There is a strong chance, if you left the bike with them, at least overnight, that the mechanic you trust did not work on your bike.
Go back, ask them to replace the hanger and purchase an additional one. Replace the hanger yourself, but understand that you will need to make sure your limits need to be reset and set up correctly.
Either the hanger is still bent, or the derailleur itself is bent. But it should not be visibly outward.
It’s in the realm that you might be able to futz with the limit screws and get it working, but if a mechanic worked on this I would expect them to have done a better job bending it into working (or telling you to replace parts).
Bike hopital
Elton John is straighter than this.
That thing is about as straight as a pride parade.
The derailleur cage always is slightly pointing outwards, slightly being the key word here.
This shit is bent
Maybe gear hanger bent or worse the cage and parallelogram on rear derailleur is bent, possibly both …
You’ll need a rear derailleur alignment tool to fix it correctly
Just buy a new derailleur hanger. That shit is fucked up.
This isn’t super complicated.
Replace cage (Shimano spare part) and hanger to get it right. Bend hanger flush with frame and cage perpendicular to derailleur lower for a suboptimal solution. There are tools your LBS should have to get this done properly. I have eyeballed this myself with a straightedge, bench vise and patience to reasonable success, your mileage may vary.
Looks bent.