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I have an old Shimano RD-M760 DEORE XT Rear Derailleur, where shifter cable cut a deep groove into the guiding steel tube. Here is a picture:

enter image description here

Is that tube replaceable? I think that groove is a contributing factor to too much friction in the cable system, which makes downshifting sluggish or skipping gears.

EDIT

Here is a wide angle picture to make my description more clear. The shifter is in the lowest gear (largest sprocket):

enter image description here

and a closeup with adjusting barrel and the cable removed:

enter image description here

The tube with a groove cut into it, is not a back end of the adjusting barrel, it is a separate part. I don't see a way to easily remove it, but it does rotate in place. Maybe I should rotate it 180 degrees, so the cable doesn't sink into the groove anymore. OTOH, the groove is so smooth and nicely shaped as if it is a part of the design. Is it, though?

EDIT 2

It seems that the groove is not a part of the original design. Here is a picture of an old Shimano RD-M760 from Ebay, showing just a slight indentation on this part nowhere near the depth I have on mine:

enter image description here

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    As a bit of photography advice, you should try to find another angle or move the cable to the side to demonstrate the issue. In this angle, it's a bit hard to see where the groove is (I though for a while that it was the scratch on the derailleur). – HAEM Apr 29 at 10:13
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    Can you show the complete cable direction? I don't know, but the derailleur is a low-normal, and from a big, empirical source of information ( bikesnobnyc.com/2020/04/15/low-is-the-new-normal ) the cable may be guided differently to avoit it being so "bended" against the housing. – EarlGrey Apr 29 at 10:20
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    Sorry for the confusion. I added more pictures and a description. – Paul Jurczak Apr 29 at 20:04
  • If you look closely at the image in the answer below, the groove is present in that derailleur as well, so it may very well be part of the design and not a sign of wear – Andrew Apr 29 at 23:19
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    Those things can be taken out and with a punch and pressed back in if you want. Get one of the long-nosed Shimano ferrules to eliminate the problem you're having. – Nathan Knutson Apr 30 at 2:14
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I was able to rotate the grooved tube 180 degrees with a flat screwdriver wedged into the groove. I cleaned the area and applied a bit of Crazy Glue around the tube. The shifter cable is now in contact with the unworn part of this tube and excessive friction in the system is gone.

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  • If it works, it works! However, I wonder about the overall orientation of your derailleur, is the cage straight? And the derailleur hanger? On one hand, I have doubts because it seems to be there is too much outward "angle" (on the horizontal plane) between the part with the groove and the cable holder on the derailleur. On the other hand, as you showed in the eBay picture, there is a small notch in exactly the same position: maybe it is really a feature (and not a bug ;) ) – EarlGrey May 4 at 12:28
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    Derailleur seems to be in very good shape mechanically. I took it off and cleaned it up. Hinges and pivots don't show any signs of wear and the geometry looks straight. Incidentally, I was in a bike store to get a new cable housing and I took a look at a corresponding cable exit in some modern higher end shifter designs. They had the same problem of cable exiting at an angle and rubbing against a guiding tube. The upside was that the tube is a part of an easily replaceable adjuster, not a press-fit steel ring like in my case. – Paul Jurczak May 4 at 20:07

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