My mountain bike has internally routed cables and and I'm struggling with indexing. My first thought is to replace my cables which I've never done.

Is it as simple as pulling the inner cable out and replacing it with a new one or do i need to replace the sheathing as well?

  • This procedure is a lot simpler with something like Park Tool IR-1.2.
    – Batman
    Apr 22 '17 at 14:45
  • But do I need to replace the sheathing? Apr 22 '17 at 17:16

There are many different shift cable and housing arrangements found on internally routed frames. For example, one end of the spectrum is bare cables running all the way through the frame with plastic cable guides to route them around the BB, and the opposite end is just a continuous run of housing routed internally. The best procedure is dictated by what kind of configuration you've got, or in some cases what options the frame offers.

Replacing just the cable is easy on some frames but enough of a pain on others that it's better to replace the housing too so that you know everything is fresh and perfect and you won't have to do it twice.

Your best friend when doing this is often a supply of cable liner, available from bike shops, which you'll cut to length, use some tricks to feed through the frame in place of the old cable as you pull it out, and feed the new cable into.


If you're going to all this effort you should change the outer too, not just the inner.

To decide what is inside the frame for internal routing.

First, push/pull the outer housing where it passes through the frame. Watch the other end for movement. If if moves you have continuous housing which is easy.

  • First, if you will need a cable ferrule at the brake/gear lever, fit it to the inner cable before threadding
  • Simply remove the old inner and fit a replacement.
  • To change the outer, you hold the new inner and pull the outer, leaving the inner in place through the frame.
  • Cut your new outer to length compared to the old one.
  • Feed the new outer over the new inner from the back, so that the new inner works as a lead wire. Ideally your new inner will be long enough to pop out the end of the outer before the front end of the outer enters the frame, to give you something to hold.
  • When the front of the outer hits the frame exit, you'll probably need to jiggle it to line up.
  • Finally fit the rear ferrule and seat both ends, then fit the inner to the rear brake caliper or the front/rear derailleur as appropriate.

Otherwise it gets harder because you have cable stops at the entrance/exit. If the cable stops are joined internally by some guide, then its also easy to pull the inner and push the new one through. HOWEVER if you have bare inner cable between the cable stops that is the hardest, and I don't have a good answer.

  • Pull the old inner wire
  • Cut and fit pieces of outer to the right length, fit ferrules.
  • Push the inner from front to back.
  • If it doesn't pop out the rear cable stop, then you have no internal housing and need a bike shop to do it, or look at buying the cable tools.

Also, some bikes have cable stops that can be removed to show a larger hole in the frame. If your rear cable stop comes out, then you can use a loop of string or tape or even a small magnet to fish the steel inner cable from the frame.

Note stainless steel is not as magnetic as regular steel.

  • I consider it very problematic to pull the inner wire in the "inner wire in frame" scenario. By pulling the inner wire without knowing whether there is a cable guide inside the frame, you are pulling away your only opportunity for installing a new inner wire. Instead, one should find a long flexible plastic tube with inside diameter the same as the inner wire diameter and outside diameter only slightly larger. Push the flexible plastic tube using the old inner wire as a guide. Then remove the old inner wire, holding the plastic tube in place. Then install new inner wire and remove plastic tube
    – juhist
    Jan 24 at 17:53
  • Some bicycle brake and shifting cable kits come with these flexible plastic tubes, for the reason of making it easy to use the plastic tube as a guide for installing a new inner wire. The plastic tubes are reusable, so one needs to buy only one such kit for brakes and another such kit for shifting cables in one's lifetime.
    – juhist
    Jan 24 at 17:55
  • Also, most inner wires are of the proper size, not twice the proper size, so using a regular size inner wire as a guide to push the housing in won't work because the housing is longer than the fragment of the inner wire visible at the back of the frame. To make things easier, you should purchase one very long (tandem sized) shifting inner wire and one very long (tandem sized) braking inner wire. Then those extraordinarily long inner wires are only used as a guide to push the new housing in, and after the housing has been changed, the tandem-sized inner wires are replaced with regular wires.
    – juhist
    Jan 24 at 17:59
  • @juhist that sounds like an answer in its own right.
    – Criggie
    Jan 24 at 18:52

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