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I'm trying to fix up my old (1999) Trek 4500, and I've run into a snag while adjusting the front derailleur. It's a Shimano FD-CT92 (bottom bracket mounted E-type), and it's rubbing against the largest chainring when it's in the middle gear position. There doesn't seem to be any height adjustement on that type of shifter. I've checked all the documentation I could find, and the chainrings are within spec (42T, 34T, 24T). In any case, all the equipment is original to the bike, and I've never had this problem before.... Any ideas on how to fix this?

Here's some additional info:

This is what the derailleur looks like when it's in the middle chainring position

enter image description here enter image description here

The FD-CT92 derailleur is bolted to the bottom bracket plate in a way that prevents any height adjustment. A flange that fits around the seat tube also keeps the angle fixed.

(the photo below is with the derailleur detached from the bracket plate)

enter image description here

The only other thing that I've noticed is that the cage can be wiggled around a bit. Is that normal? Do derailleurs wear out?

enter image description here

  • Has it become bent out of shape or slipped round out of alignment? – Amos Aug 28 '14 at 7:30
  • I wish it was that simple, but it doesn't seem to be damaged in any way. – KootenayRaph Aug 28 '14 at 18:10
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bottom bracket has come loose slightly allowing the plate to turn.

  • This answer is way short and risks deletion. But its correct and accurate, where no other answer touches on it being an e-type mech, so well done there. Could you please use "edit" to expand your answer with supporting information, like how an e-type derailleur is related to the rightness of the BB cup/ring. Separately, please browse the tour to see how SE works. But +1 for coming up with the right answer. – Criggie Jul 14 '18 at 23:14
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Sounds like it could be the tension on the cable. If its the original then replace it. If its new then look at reindexing the gears? Have a look on Sheldon Brown for a much more comprehensive run down of what it might be.

If all else fails it could be that its got rotated or slipped at some point. Just loosen the screw holding it to the frame and lift it up a few mm. Should make things a bit better.

  • The cables are fine, and the shifter is indexed so that it shifts correctly. I did go through Sheldon's website, but didn't find any info that would help (other than that e-type shifters have limited adjustments). Also, the derailleur is fixed to the bottom bracket plate in a way that precludes any height or angle adjustments. – KootenayRaph Aug 28 '14 at 18:13
  • @KootenayRaph Hmm, that is odd! Thanks for putting the photos up, as Batman said its a very well documented question. They will wear out yes, but generally its when the parts seize which this doesn't look like. Sorry I'm a bit stuck for any further advice. – s_boardman Aug 29 '14 at 12:29

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