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How to replace gear cables on your road bike: 2 top tech tweaks for smoother shifting

Do this simple mechanical job before the summer arrives for many miles of perfectly functioning gears

Fresh cables are crucial to making your bike feel brand new. Here’s why you need to do this before summer and a step-by-step guide to make the process super simple, even if you have no mechanical skills. 

While electronic gears and hydraulic disc brakes are pretty much all that you’ll find on a new bike these days, most people are still loving their rim brakes and mechanical shifters. And rightly so, because they’re still brilliant. Well, they are as long as you look after them.

As with any moving part of a bicycle, gear cables and their housing will eventually wear out or get clogged up with gunk. Gunk This causes excessive friction to occur between the shifter and the derailleur and that results in your gears not working properly. 

You’ll likely find that your chain won’t make the jump into the next cog and when you’re suffering on a hill, that’s the last thing you want. And even worse, inner cables can eventually snap, potentially leaving you stranded at the bottom of a big climb with just a single gear.

Doing this simple maintenance job will ensure that your gears are working perfectly for those long summer rides.

What tools are needed?

  • Cable cutters
  • A pick
  • File or rotary cutting tool
  • Allen keys
  • Plastic sheath

The tools that you’ll need for this job consist of a good set of cable cutters and an Allen key for the clamp bolt. We’d really recommend getting a good quality set of cutters as this will give you a clean cut of the inner cable and the housing. Cheaper side cutters can crush the housing and fray the inner cable, leading to poor shifting or difficult installation.

For a pro-level finish, a pick is really useful and a file or a rotary cutting tool will give your housing the flattest surface at the ends. It might seem small, but it’s a crucial step towards perfect shifting.

And if you’re working on internally routed cables, you’ll want to grab some plastic sheathing. Honestly, it’ll save you hours of pain.

Get set to make life easier

Ideally, we always want to be working on a clean bike. Cleaning a bike It doesn’t have to be spotless, but a drivetrain is a dirty place and a frame that is covered in road grime is not a nice place to put your hands either, so give your bike a wash before you get going.

Now that you’ve got a sparkly bike to work on, drop the chain into the little ring and the smallest cog. 

Steps

Undo cable anchor bolt and cut off the end of the cable, above where it was clamped, to leave a clean finish.

Remove the small piece of housing from the rear mech and put it to one side. Slide the plastic sheath onto the inner cable, pushing it up through the frame.

Slide it through the cable entry point and then stick the sheath in place using tape. 

Now you’ve got that in place, you can pull the cable inner all the way out and peel off the bar tape. If you want to reuse it, try to do so without ripping the tape.

Now is a good time to check your existing cable housing length. We can’t stress how important this bit is. Go too long and you’ll lose crispness in your shifts. Cut too short, though and you’ll stop the bars from being able to turn properly.

Give the bars a twist to check that they turn all the way. If everything looks good, you can use this housing to measure up the new pieces.

Grab the cable cutters and cut your housing to length. If your old stuff was the wrong length, remove the old cable inner from the shifter before sliding one end of the new housing into the shifter. Hold it in place with your hand where the bar tape would end.

Feed the housing to the frame stop. You’re looking for the straightest entry line possible while leaving enough length for the bars to turn. We want to make the cable run as smoothly as possible.

Remember that the cable stop in the frame will be a few millimetres in from the edge, so account for that by adding a few millimetres to your cut point.

Now that you’ve made your cut, it’s time to maximise your shifting performance with a couple of pro tips. The first is to square off the face of the housing so that it sits flat against the cable stop. You can do this with a metal file, but our preferred method is to use a rotary cutting tool, though you might know them better as a Dremmel. 

It doesn’t take much, so be careful. Once that is done, the second tip is to use a pick to open up the end, as the housing’s lining with likely have been crushed when you cut it.

At this point, depending on your bike’s groupset, you might need to pop a ferrule or two on to the housing. Refer to your old cable to see what you need. If you don’t have new replacements, just use the old ones if they’re in good enough condition.

Time to thread the new inner cable through the shifter body and here’s where you reap the rewards of that liner. Simply pop the new cable in, slide it through and then pull the liner out.

If you’re routing the front derailleur, simply put the cable inner through the clamp bolt and tighten it down.

For the rear derailleur, you’ll need to cut another small section of housing. Again, you can use your old piece as a reference for length, but you really just need a gradual curve from the frame stop to the derailleur stop.

Once cut, remember to use the techniques that we covered earlier to get the faces on the cable perfectly flat and open up the liner. Replace any ferrules and feed the cable inner through to the anchor bolt. 

Before you tighten it up, wind the barrel adjuster in as this will help when you come to index your gears. Speaking of which, you’re going to need to do that now, so go and check out our video on how to do just that. And then you’ll need to re-wrap your bar tape. We’ve got a video for that too. 

Son of a Marathon runner, Nephew of a National 24hr Champion, the racing genetics have completely passed him by. After joining the road.cc staff in 2016 as a reviewer, Liam quickly started writing feature articles and news pieces. After a little time living in Canada, where he spent most of his time eating poutine, Liam returned with the launch of DealClincher, taking over the Editor role at the start of 2018. At the weekend, Liam can be found racing on the road both in the UK and abroad, though he prefers the muddy fields of cyclocross. To date, his biggest race win is to the front of the cafe queue.

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