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    Troubleshoot my derailluer please.

    Had this bike in and out of 3 different shops across Manchester and still ride it out with an issue.

    Could I get a diagnosis from the 2 pictures as to why the derailleur is scrunched in first photo (today) vs the second photo (straight back from service). The chain keeps throwing itself off randomly and none of the gearing is reliable (not experienced enough to see why).

    Side note: I want to learn how to setup and tune bicycle gearing so please recommend any websites or YouTube accounts with solid guidance.

    Thanks in advance.

    by TheMassaB

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    6 Comments

    1. Brisollie on

      In the first picture the derailleur is set up correctly but the chain is too long. And in the second picture the derailleur is set up incorrectly, looks like the clutch is fucked.
      Where does the chain fall off?

      Also the cable is routed badly

    2. HG1998 on

      So whoever did the work leading to the second photo, stop visiting them.

      I can’t even really come up with an idea of how the derailleur is under tension while in the smallest gear, except if they somehow broke the derailleur spring.

      What you can do is disengaging the chain from the front chainring and see what happens. If the derailleur crunches up, then we’d at least know that it is fine.

    3. Dramatic-Search-2248 on

      Has the b screw skipped over the stop, or threaded itself? It’s it defo tight at point where derailleur tightens to hanger, as I’ve seen b screw skip stop in these instances.

      Also give gear cable outter a little slack to remove that as an issue.

      Hanger is tight?

      If not any of these, drop chain, as already mentioned, does it scrunch up as already said. Should rotate around hanger pivot / faster point, and also cage should move up. Could be spring at hanger/ fastener pivot point. More thank likely

    5. doncrescas on

      In the earlier picture straight back from service the derailleur was tightened without resting the tensions screw nib against the derailleur hanger. By the second picture it looks like due to the tension from the chain pulling on it it rotated forward and is now sitting somewhat normally but the chain is slightly too long. There appears to be some damage to the outside of the derailleur, which would indicate that the hanger should definitely be checked for alignment.

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