Like topic, this may be a daft question. I tried google but sometimes it has too much info and nothing to do with what you want.

I suspect my rear derailleur cage is bent/twisted.

I have 1x9 gears.
Im getting bother with my 1st and 2nd gear, and when looking at it, the pulley wheels seem to be running at a bit of an angle to the chain rings when in 1st and 2nd gear. Seems to align better once in 3rd and up and i dont get any bother with those gears

Should the pulley wheels be aligned/parallel with each individual gear ring? Or will you have a bit of misalignment due to only being 1 gear at front so it has to run at angle?

Im thinking only the chain should go at an angle and everything else should be straight, but double checking

Upper and lower pulleys should be in alignment when viewed from the rear.

*oooh I say*

These should be in line with your chosen gear on the cassette.

If the upper and lower are in line with each other, but at an angle offset from the cassette - you've possibly bent your mech hanger a bit. As in, the top of your mech is the pivot point they are hinging about.
If the upper and lower are not in line, but the upper is with the cassette - you've more than likely bent your mech. As in, there is a pivot point along your mech cage.

Both can be fixed.

If the lower is in line with the cassette and the upper is not - you've broken physics.

However, some mechs do have some play develop in them over time - cheaper SRAM mechs certainly do, older non Shadow Shimano mechs also. Easiest may be photos.

Alright thanks, will have a proper look tommorrow. Been giving bother for a few weeks now after i had a mishap, and i thought there was something bent, but couldnt see anything. Was only tonight when fiddling that i noticed the upper pulley was at an angle across the first and 2nd gears when in each one.

Wouldn't hurt to check hanger alignment.


192 (02-07-2017) by Chris Reeves, on Flickr

I was going to mention the magic of hanger alignment tools!
When I had a problem, on popping into LBS, the mechanic pulled one out and pointed out how the hanger was bent, and also another very similar tool to point out that I'd bent my brake disk, probably at the same time.

And then proceeded to add judicious force to various bits of both of them, and made it all lovely and straight again :D

If the lower is in line with the cassette and the upper is not - you've broken physics.

Or the cage.

It is also possible that your jockey wheel
Bushes/bearings are worn out.
This process can be accelerated by having a bent/slightly misaligned derailleur cage and or hanger.
Beware of derailleur-spoke interference in the lowest gear after any cage/hanger tweaking however tentative!

Alright, so thanks for the replys. Had a closer look earlier now that i knew what i was looking for.

The cage had very slight twist on it, but nothing. It was actually the hanger that was bent. Didnt notice it untill i started measuring. Very slight, only 2mm or so bent in towards the spokes.
Had to take everything off so i could straighten it out. Still not perfectly straight, but the gears are better now than they were. Will give it a try at the weekend and see how it goes, if not very well then i'll just buy another hanger.


Shouldnt be anything worn out thats causing it,i hope. I only bought the bike a couple of weeks ago, and it was my very first trip out on it that i had a mishap, typical

Top and bottom jockeys will not be in alignment if the mech is a bit worn - the chainring will drag the bottom jockey over a bit. This is all fine and not a requirement for a new rear mech (or a pry bar!) If you think the cage is twisted unbolt it and check it for flatness on a sheet of glass.