3

The derailleur is not extended. The cable tension seems ok. What could be the problem?

enter image description here

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  • Chain too short? Does it work okay on the bigger chainrings and sprockets? Did you change anything? (like installing a new chain without shortening it)
    – Michael
    Commented Jan 5, 2023 at 18:56
  • 3
    I would have thought a chain too long could be causing that. But I didn't change the chain.
    – Erwann
    Commented Jan 5, 2023 at 18:59
  • 2
    @Erwann you're right that the chain being too long would be the problem. Can you post a photo (with better lighting) of the derailleur on the largest cog?
    – Paul H
    Commented Jan 5, 2023 at 19:27
  • If the chain length has not changed, is it cross chained - what is happening up front on the chain rings? Has it always been this way?
    – mattnz
    Commented Jan 5, 2023 at 20:05
  • Ooops, I meant too long of course.
    – Michael
    Commented Jan 5, 2023 at 20:46

3 Answers 3

5

It seems like your derailleur is mounted at an improper angle. Check out this picture for reference:

enter image description here

You can see how the part that says "Claris" is pretty much horizontal in the photo, whereas on your bike it's pointing 45 degrees down. Try loosening the mounting bolt a little, and then rotating the derailleur mount counterclockwise as to replicate the above picture. Also, check that the B-stop/B-screw (as applicable) is butted up against the little tab on the derailleur hanger. Right now, I'd imagine there's quite a large gap.

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  • OK, I see what you mean. When I try I'll post an update.
    – Erwann
    Commented Jan 6, 2023 at 4:02
  • It also looks like you're using a "claw-type" derailleur hangar and that isn't mounted to the bike dropout area correctly and/or is not positioned correctly relative to the dropout. Typically the claw mount hangar's "dropout" aspect (for lack of a better term. The area that is secured by the wheel's axle) should parallel the bike's dropout. You should be able to insert and remove the rear wheel into or out of the dropouts with the derailleur andi it's claw correctly installed since the claw sits flush on the dropout sharing the open orientation of the dropout to accept the axle/wheel
    – Jeff
    Commented Jan 9, 2023 at 9:01
  • @Jeff I think it's a regular hanger (looks too thick to be one of those crappy stamped steel claw ones), and it seems to be installed correctly. You can see the chainring bolt-style mounting bolt. There's no way that thing would be in if the hanger was misaligned. It would be best if OP confirmed their situation with us of course.
    – MaplePanda
    Commented Jan 9, 2023 at 9:06
  • @Maple Panda IDK. I'm also drawn to where the cage is touching the body by the barrel adjuster. Seems like it is or would get hung up there. If you imagine squeezing together the fixing bolt and barrel adjuster area to mimic cable activation. The cage moves down and in (or away from the pics perspective) but it may be hung there. Anyway--thats not the chief problem if it's one at all.
    – Jeff
    Commented Jan 9, 2023 at 9:20
  • Something's not right with the B-axle/B-Screw assembly as your answer states. The other side holds all the answers (-:
    – Jeff
    Commented Jan 9, 2023 at 9:26
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The problem is a derailleur awkwardly oriented in low/low gear such that the bottom part of the chain almost rubs the upper pulley (2). The chain wasn't worn, if I'm reading it correctly (6,7). And replacing the slightly bent hanger did not solve the problem. It has been suggested that the derailleur was mounted at an improper angle, and that the body should be horizontal. But the photo taken for comparison is not in low rear gear. Tilting the body horizontally manually just makes the chain slack (1). So I removed a chain link, and that (seems to have) solved the problem (3). (4) and (5) show front gear on high, and with B-screw tight and loose respectively (the latter seems to put less tension on the derailleur).

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0

Does your shifter click up or down?

Can you move the derailleur by hand, to the largest cog?

I doubt it's a derailleur problem. Untie the cable, and try moving it by hand. I don't think it's derailleur or chain related. My guess is, you have a sticky or broken shifter.

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