In a previous installment, I walked through the internal cable routing arrangement of Giant’s TCX SLR 2 cyclocross bicycle. Today I’ll show you how to actually replace a rear shift cable on it. You may remember I broke mine not too long ago.
For this job we’ll need new shift cable and a pair of cable cutters. I’m reusing the old cable housings for now, but ideally it would be best to replace those at the same time.
REMOVING OLD REAR SHIFT CABLE
Job one is to undo the bar tape, and either peel back or completely remove the brake hoods. This is mainly to expose the cable housings and the cable exit hole on the control levers. On my Shimano 105 ST-5700 levers, they’re at the bottom of the lever body.
Use the shift levers to release all cable tension by shifting to the smallest cog. This will expose the bulb of the cable head into the cable exit hole to facilitate removal.
Normally you should be able to expose the shift cable, free it from the rear derailleur’s cable clamp bolt, and push it through the housings in order to remove the shift cable from the control lever. In this particular case though, the shift cable snapped inside my right STI lever, so that’s not feasible. I had to pick and pry the cable head bulb with a hobby knife to get it out.
Yep, that’s a nasty fray.
Next, get a paper towel and soak a bit of it in wet chain lube. Take your new shift cable and run its entire length through the lube-soaked paper towel. This cleans and lubricates it.
INSERTING NEW SHIFT CABLE
Insert the shift cable into the exit hole and pull it through the control lever body. Make sure that the cable end is fully seated inside the control lever by pulling it tight.
Next, run the shift cable into a ferrule, then the length of cable housing for the handlebars. Seat the ferrule into the control lever body. At this point, you can return the brake hoods to their normal position on the control levers.
The cable housing runs into the downtube and pops out around the bottom bracket shell area, looping around it before re-entering the frame into the drive-side chainstay. Shortly, this brings us to the most…”involved” part of the whole operation.
Pull out the cable housing from the routing hole leading into the drive-side chainstay. This exposes the ferrule on this segment of cable housing. Push the shift cable through until it comes out of the housing and ferrule.
THE CHALLENGE
Giant uses an internal liner that enters the drive-side chainstay at the rear dropout area, anchors there, and terminates inside the chainstay. When you pull the whole thing out, it looks like this:
The inside of the cable routing hole of the drive-side chainstay has this U-shaped slot that is supposed to both accept a cable housing ferrule and keep the thin end of the liner in place. If it works, it should be easy enough to feed the shift cable in.
In practice, it can get dislodged from there. This is the biggest challenge of the cable replacement job.
If the liner gets dislodged from its retaining slot, you’ll have to manipulate it at the dropout end by pulling it free and turning it around. It feels like a bit of a lottery to get it in, but be patient. The cavity is relatively small so there’s not much place for the liner tubing to go.
Once the liner tubing is sitting where it should, feed the inner cable through.
Continue pushing along its length and it should pop out at the rear dropout area next to your cassette. As you feed more cable, insert the ferrule and cable housing back into the routing hole around the bottom bracket shell until fully seated.
THE HOME STRETCH
We come to the final loop of cable housing feeding into the rear derailleur. This length should have ferrules at both ends.
Run the cable into the barrel adjuster on the rear derailleur, then into its cable clamp bolt.
Seat the final ferrule into the barrel adjuster and pull the shift cable as tight as you can. Get your 5 mm hex wrench and tighten the cable clamp bolt.
You should have a bit of excess cable left. This is way too long, though. All you need is an inch or so past the cable clamp bolt.
Break out the cable cutters and snip off the excess cable. Slip a cable cap on the end and crimp it with the same tool so that the cable doesn’t fray at the end or stab you.
Job done! Now all you need to do is set your rear gear indexing and perform test shifts.
the accidental randonneur 