My previous set of road shift cables (Shimano, not sure of the exact model) included one special ferrule that has a much thinner section of ferrule sticking out past the end, and a keying ridge on the side meant to slot into the last housing boss before the rear derailleur.

It's the lower one in this picture:

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Here it is installed, no cable:

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What role does that special ferrule serve?

Is it critical or just a nice to have?

I'm replacing the housing with Jagwire and I just got generic plastic ferrules for all the shift housing ends, like the upper one shown above, so I don't have a fresh one of those special ferrules.

Based on answers to the above, should I replace the special ferrule with a fresh generic one? Or reuse the old special one in that location despite it being about 5 yrs/ 10,000km old? The compression wires of the old housing are extruded by about 1mm, which I usually take as an indication the ferrule should be replaced (especially if plastic):

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1 Answer 1


The ferrule is called a long tongue cap. It helps keep dirt out of the housing. This is the cap Shimano recommends using on the non-derailleur side of this housing section.

As this helps keep dirt outside, I would say it is a nice to have but not critical. If you have easily access to buying a new long tongue cap, since you are already doing the work of replacing the cable and housing, I would get one.

I think it also goes with the rest. If you use premium cable and housing to lesser the friction, then go for the better cap. If you use entry-level cable/housing, I think it is alright to use a generic new cap.

  • 1
    Is it worth re-using the Shimano one or replacing with a new (presumably generic) one from the fresh kit?
    – Swifty
    Apr 23, 2023 at 14:16
  • 1
    I would go with a new generic one to make sure it has a tight fit on the housing which I think would offer a better dust protection/performance than a worn long tongue cap.
    – olliebulle
    Apr 23, 2023 at 14:23
  • 2
    Thanks for the answer and tips. Unfortunately I don't have easy access to replacement parts right in my current city. Just what I brought with me. So based on your second comment, I checked the fit of the old long tongue cap, and it's pretty tight on the new housing. So I decided to reuse it rather than replace it with a generic ferrule. I'll see how this goes.
    – SSilk
    Apr 23, 2023 at 15:46

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