DenveScubaSteve

Hey all,

I am having a slight problem with my rear derailleur, it is not parallel to the gears. It's not horrible and still perfectly ride-able but I want to fix it before too much longer. My first thought was a bent hanger, though when I went to go take a look last night there was something even more interesting happening.
Where the derailleur attached to the hanger (the one bolt) there is some play/movement from the hanger.
The hanger does not move, but I can wiggle the derailleur and see movement from the pivot bolt attachment to the hanger. If that makes sense.
I have loosened and the tightened the derailleur bolt but still have play.
Maybe its the washers on the bolt?
Any thoughts?

moxfyre

I'm confused... is the derailer loose in the hanger, or is the hanger loose in the frame? I think you mean the former: "the derailer is loose in the hanger."

Is it possible (unlikely) that the female threads of the derailer hanger are stripped? With aluminum frames, they are generally soft aluminum hangers, and I imagine this could happen. If so, new hanger... typically $20-30.

What do you mean by the washers on the bolt? Normally there are no free washers on the derailer mounting bolt, but perhaps you mean something that's actually part of the derailer body?

DenveScubaSteve

Sorry for the confusion, These are good questions, I just wasn't sure how to convey what I am seeing.

1) I do mean the former "The derailer is loose in the hanger"
2) The threads do not seem to be stripped as I can tighten and loosen. I have it as tight as it can go.
3) It looked like there were washers (small black ones) on the derailer, between the derailer and the hanger. This could just be part of the derailer assembly.

moxfyre

No worries, I just like to make sure I am answering the right problem! So, to summarize... you can tighten down the derailer against the derailer hanger and torque the bolt sufficiently. But then there is still some play in the derailer.

The washers that you are referring to are part of the derailer, yes, and not easily removable. Possibly they could crack or bend, although I have not seen that myself. Is there any sign of that?

Are you sure that the derailer is correctly seated on the hanger? As in, the B-tension screw of the derailer is seated against the little protrusion from the bottom of the derailer hanger. I can't find a good picture of this, sorry.

Are you sure that the looseness is in the attachment of the derailer, and not in the derailer pivots, or a bent cage? What model of derailer is it?

DenveScubaSteve

Precisely!


The model is Shimano STX its on my Cannondale M400.
The B-Tension screw looks to be seated correct. I will verify.
I am sure that the looseness is in the attachement and not the pivots as I can see the derailer on the hanger move.

moxfyre

Well, if the derailer is correctly seated and there's nothing cracked or bent on the hanger bolt, then I'm afraid I'm stumped

Anyone else?

peripatetic

OP should post a pic.

bikeman715

the dérailleur maybe toast and need to be replace. if you remove the dérailleur there is a c- chip which hold the mounting bolt which goes into the hanger. you'll see a spring is it broken ? replace, repack with grease and put the c chip back on. remount on bike.

kamtsa

I have the same situation with my SRAM SX-5 ESP RD. It is relatively new with only few hundreds miles.

When I remove the chain, the derailleur has side to side play. When I put the chain back, the derailleur tension holds the derailleur on one side of the free play range. The play is not between the frame and the derailleur bolt but between the bolt and the derailleur body. Something internal to the derailleur (the bolt is fully tightened).

I have not noticed any shifting problem so far so I don't worry much about it (should I?).

Kam

DenveScubaSteve

I thought about it, but how about a video instead!

Here's a link to the video of what is going on.
Youtube linky

DanBraden

I've been wondering about the exact same sort of movement from my own derailleur. I started examining my derailleur when gears started being skipped when I began pedaling hard. For instance I might have stopped in higher gear than I normally do, and when I hammer down, I hear a "CHUNK!" and the chain feels like it momentarily skips. However, if I am in a lower gear from a stop there is no "skip". Anyway, I was wondering if the derailleur was flexing in when I pedal. Anyone know if all derailleurs do this?

bikeman715

most derailleurs do this but not to the point than you would feel or hear it.

Wordbiker

If it's what I think it is...it's easily fixed.

Many replaceable hangers are fastened with a single chainring bolt. Due to variances in manufacturing tolerances, sometimes the hanger and dropout are narrower than designed and this bolt bottoms out before truly clamping down on the hanger and frame. Remove the bolt, take a file to it and remove a mm or so from the end (you can also rub it on a piece of emery cloth or sandpaper since it's usually soft aluminum) regrease and install again. If you're lucky you may be able to find a washer to fit it, but removing the material is a permanent fix. I've found several brand new bikes with this exact issue.

Hmmm...on a re-read of the OP it also sounds like it may be partially stripped threads on the hanger or even play in the upper pivot bushing.

moxfyre

That's useful. As far as I can see from the video, there's little to no flex in the derailer itself. Harder to tell about the hanger, but I don't think the hanger itself is loose or flexing either.

OP has already said that the hanger is not loose. (OP, can you double-check that the hanger fastening bolt is tight and doesn't wiggle?)

I don't see any play in the derailer itself from the video.

The OP said that the threads on the hanger aren't stripped either. But to my mind this is the only plausible explanation. It's possible that the threads are only partially stripped, as you suggest, so that the bolt will seem to tighten down but still has a lot of lateral slop in it...

peripatetic

Maybe the pivot's missing the o-ring/washer it often has? Or it's become degraded somehow? Maybe remove the derailleur from the hanger to see if there's something wrong at that interface?

moxfyre

+1

It's worth checking... that didn't jump out at me from the video, but it's quite plausible.

DenveScubaSteve

That's what I am going to check out. I will take the derailer off and see if there is anything wrong with it, but I am thinking that it may be one of the bushings.

I was going to try a washer to see if that will work. Once I pull it off I can get a better feel for it.

There is no movement in the hanger, but I will check and see if it can be tightened.

DenveScubaSteve

Well, I took the derailer off today and found nothing wrong with it.

It is still shifting well, so I am not sure what is going on.
I could file the bolt down to try to make it tighter or just add a washer and then tighten it down.

Any other thoughts?

operator

Why don't you just bolt another derailleur on that you know is good? It almost sounds like you're worrying about something normal.

moxfyre

Probably the best advice for the moment... if it's shifting well, just keep using it. If it stops working well, get a new one. It sounds like you've established pretty conclusively that there's nothing wrong with the frame or hanger, so don't worry...

DenveScubaSteve

Yeppers, That was my thought.

It is shifting pretty well, no main problems so I am just going to use it until I "want" to upgrade or it breaks.
Thanks for all your help!

DenveScubaSteve

Installed a washer this past weekend, with a little negotiating. This took care of the slight movement on the hanger. There is still some play in the cage but it is acceptable for this price of a derailleur.
It now shifts a whole heck of a lot better. Thanks for the suggestion guys.

Retro Grouch 

You make that sound so easy to do.

In reality it requires the use of words that only bike mechanics are allowed to say.

escii_35

Zombie Resurrection:

Yeah for the internet.

Loose cannondale derailleur hanger + 17 year old stx-rc = all the symptoms described by posters. Especially scary is the one described above.

It began with the ability of my friction shifter having issues holding a gear and ended with me freaking out due to the " chunk" described above and riding home at 5mph. After a two screw tighten. All better. The RD is getting wobbley compared to my 1yo deore and my hardly used Sachs. It will be replaced next spring.

techsensei

I kinda skimmed through the thread, so forgive me if you got your answer or whatever. But a hanger can certainly be straight and the derailleur itself be bent. Also the less expensive the derailleur is, the more loose in the pivots are to begin with. That why people buy/want better derailleurs and other parts, because they are built to tighter tolerances, and last longer without getting all wobbly from wear. That said, a seven-speed system can tolerate much more play than 9-10-11 speed clusters where the cogs are much closer together.