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My rear derailleur barrel adjuster has unscrewed completely and now I can't get it back in.

Is it likely that I've damaged something here, or is there some special technique to screw in barrel adjusters that I don't know about!?

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    It sounds like the threads might be fouled. Probably best take to a bike shop. – Daniel R Hicks Aug 7 '14 at 11:51
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    Have you completely detached the cable? Or are you trying to get it back in with the cable still going through the barrel adjuster. If you haven't removed the cable or at least loosened the clamp nut (or whatever it's called) to let the cable the cable go slack then you might not be aligning things properly. – Kibbee Aug 7 '14 at 12:28
  • I removed the cable completely and tried to screw the adjuster into the derailleur directly with no success. – Robert Dougan Aug 7 '14 at 15:15
  • Can you post some close-up photos of the adjuster and the derailleur? – stranger Aug 7 '14 at 15:47
  • There are three parts: a threaded tube, a spring and the plastic barrel. The tube fits into the barrel and the spring goes over the threads. You screw the adjuster in while pushing the tube with a fingertip. You might screw the tube in first to check if the threading is OK! – Carel Aug 7 '14 at 17:03
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just in case someone else stumbles upon this while trying to solve a busted thread for the barrel adjuster, I managed to solve this yesterday by rethreading the aluminium derailleur housing gradually by going with smaller size thread screws first, then finishin with m5, that's the size of the barrel adjuster screw thread, which was in my case still intact. The problem was that a bike mech was lazy and didn't want to adjust the cable tension manually, so he/she unscrewed the barrel adjuster so far out of the derailleur, that it only held itself in place by 2/3 bends, in which case the leverage on those bends in case of an impact on the barrel adjuster is so great, that the soft aluminium thread inside the housing has no chance of withstanding that.

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  • This sounds exactly like what's happened to my bike. I got new cables put in by my LBS.. I won't use that LBS again. – John Hunt Jul 7 at 9:00
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There are three parts: a threaded tube, a spring and the plastic barrel. The tube fits into the barrel and the spring goes over the threads, then the cable goes up the middle of all of them. You screw the adjuster in while pushing the tube with a fingertip. You might screw the tube in first to check if the threading in the derailleur is ok, but usually that's not necessary.

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This answer might help one like me, because the same problem occured for me, barrel adjuster completely unthreaded and could not tighten back into derailleur. Things to do:

  1. Don't panic and try tightening a lot, it would worse your situation
  2. barrel adjuster get tighten to derailleur, only thread taphole and barrel adjuster screw are inline
  3. Try to get tap hole(threaded hole) in derailleur inline to barrel adjuster screw, if you couldn't
  4. Now remove the cable from rear derailleur and barrel adjuster.
  5. in barrel adjuster, take screw alone and try to tighten it in tap hole of derailleur, tighten and loose it 2 to 3 times to make it align to thread.(see barrel adjuster assembly components above)
  6. Now place your barrel adjuster assembly and tighten it clockwise into derailleur. After fully tightening, turn anticlockwise 2 to 3 turns.
  7. assemble your cable into barrel adjuster and derailleur.
  8. put your chain in smallest rear gear and shift lever position to last. Without slack on cable, pull with cutting Blair, tighten the fixing screw or nut.
  9. Try to shift to one large gear on rear, if it does not shift, cable is still loose, retighten the cable and fix once again
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  • Good first answer - what's a "cutting Blair" ? Pliers perhaps ? – Criggie May 25 at 6:20

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