Replacing Internally Routed Brake Cable

| July 21, 2018 2:10 pm

by Franz Kelsch

For some time I have been planning to replace the brake cables and housing on my 2014 Trek Domane. I had all the Shimano DuraAce parts and tools, even some tools for working with internal routing of cables, but was always a bit hesitant getting the rear brake cable through the frame.

Then I saw on Amazon this Jagwire tubing that would just fit over the cable. It only costs $10 for many feet of the stuff.

I figure that would make it easy. I cut the end cap off the rear cable and threaded a piece of this Jagwire tubing over the cable before removing, starting with the rear entry port. I was able to slide the tubing over without any issue, but ended up having a problem, because the tubing would not exit the front entry port. I had to finally remove the cable and checked again to see if I should had threaded the tubing from the front, but even with nothing in the way the tubing still had an OD too big. Dumb Trek design.  If the front port was slightly larger it would still easily hold the cable housing (as the rear port does) and you could use tubing to make replacing the able easier.  So I went back to my original plan to use the Park magnet kit I had bought.  See instructions from Park Tools.

I had also bought some new Park cable cutters thinking the cable cutters I have been using were too cheaply made. I cut the new housing to match the length of the removed housing. Opps, I was in our 2nd home and I didn’t have an Awl to make sure the end where I cut was rounded, open and clear. So I headed to Ace Hardware which was closest, but no luck, so over to Lowes since it was closest to where I as now, and they had nothing. I ask asked two sales assistance and the kids they hire didn’t even know what I was talking about. So I finally drove over to Home Depot and found it right away.

I found another secret, leave some of the old cable you will be discarding inside the new cable housing where you will cut and cut through both. It leaves the housing in better condition where you make the cut. Use the Park cable cutter to round the cable if needed, then use the awl to make sure the opening is clear and well rounded.

Now the part I dreaded, using the magnets to fish the cable through. It took me maybe 20-25 minutes but finally was successful. On the rear entry port there is a piece you can remove by using a 2 mm Allen wrench, so it is a bigger opening to work with. Otherwise I doubt I would have been successful.

Of course I should have paid the have the cable and housing replaced and it would have been cheaper than everything I had bought, but what fun would have been. I used the brakes the next day on a long descent and they worked great.

I should mention that I have replaced many brake and derailleur cables and housing over the years so I am not totally inexperienced but this was the first time with internal routing.  I feel confident I could do it now and if a bike allows the Jagwire tubing to go through both front and rear port, the job would be very easy.

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