19
Is my derailleur: broken, crap or something else (lemmy.world)
submitted 1 month ago by to c/bikewrench@lemmy.world
11 comments fedilink hide all child comments
 

One way it's too loose

The other way it's too tight

This 1x7 bike has been fine for ages but I left it way too long to change the chain. So I bought a new chain and a new SRAM 7 speed cassette and swapped them over.

The derailleur is admittedly cheap (SRAM X-4) but I feel like it should be folding back on itself when using the small cog to avoid the slack chain. I've definitely sized the chain at least a link too small but as you see, it's mad slack. It was similar before I replaced the parts but not as bad.

There's also a pretty nasty grinding/friction-y noise coming from somewhere when I put power through the pedals, especially in the lower gears. On the stand it's spinning and shifting fine, even with the slack chain

Any suggestions? I probably need a more beefy SRAM MTB rear mech?

all 11 comments

sorted by: hot top controversial new old
[–] 10 points 1 month ago (5 children)

That chain is too tight

While you're in there fixing the chain check the spring and lube the pivot

  • permalink
  • fedilink
  • source
  • hideshow 5 child comments
    •
  • [–] 5 points 1 month ago (1 child)

    But too loose in the first pic. Something is stuck on the derailleur.

  • permalink
  • fedilink
  • source
  • parent
  • hideshow 1 child comment
    •
  • [–] [S] 3 points 1 month ago (2 children)

    It is way too tight. I originally sized it Big to Big (well I only have a single ring at the front so that's always big), then adding two links.

    This was my misguided attempt to try and take the slack out in the higher gears but I could see straight away it's barely engaged in the low gears so I'll try again.

    It doesn't feel like this derailleur has enough power in the spring to put enough tension on.. I'm using a SRAM shifter with SRAM derailleur and cassette, I have some old Shimano derailleurs, in theory should the pull ratio be compatible?

  • permalink
  • fedilink
  • source
  • parent
  • hideshow 2 child comments
    •
  • [–] 2 points 1 month ago (1 child)

    In this era and level I'm not sure but it'll probably work. I used big/big add link and never had issues so maybe double check that. I think all the weird torgue that came from the short chain has probably damaged the cage pivot.

    I'd just pop it all apart clean and lube everything, measure the chain, and put it all back together.

  • permalink
  • fedilink
  • source
  • parent
  • hideshow 1 child comment
    •
    • [–] 4 points 1 month ago (4 children)

    The cage is failing to double back on itself to retain tension and I'm fairly sure I don't see a lock on the derailleur itself so I would say the spring mechanism has failed for some reason.

    With only a single chainring in the front, you could get any short cage mtb derailleur for cheap and swap it out in a jiffy. That'd be the route I'd take.

  • permalink
  • fedilink
  • source
  • hideshow 4 child comments
    •
  • [–] 5 points 1 month ago (3 children)

    Yeah this ,there is likely a little button you can push too keep it extended like this ( for working on it?) should self release but might be bit stuck

  • permalink
  • fedilink
  • source
  • parent
  • hideshow 3 child comments
    •
  • [–] [S] 1 point 1 month ago (2 children)

    I think it's too cheap to have a clutch

  • permalink
  • fedilink
  • source
  • parent
  • hideshow 2 child comments
    •