Brake cables are quite literally a life line. Fortunately, it's a robust system but you do need
to keep an eye on maintaining them in order to make sure that they're safe and that you're
getting the best braking performance, so every now and again, replace the cables. It's not
a hard job to do and we're going to show you how to do it now. You are going to of course
need some replacement cables but in terms of tools, what you're going to need is an
allen key - generally a 5mm one - and a good quality set of cable cutters. And if you want
to do a really professional job you're also going to want a file like this and a little
pick like this and then just follow our simple steps.
Firstly, as we're replacing both the inner and outer cables, we need to undo the upper
part of our grip tape. If it's in good condition, do it carefully so you can just wrap it back
afterwards, but if it's not, why not put some new tape on while you're at it? You can find
a link on how to wrap bar tape in the description below this video.
Once the cables are exposed, take a look at how they are arranged against the bars before
you remove the tape that's holding them in place.
Now we'll start with the front brake. Loosen the crimping bolt with your allen key, normally
a 5mm. You can then pull the cable clear. If it's really frayed, then it's a good idea
to cut that part off with your cable cutters to make things easier when it comes to getting
the cable completely out.
OK next, on our model of shifters - Ultegra, a few years old - we need to undo this little
cap in order to get to the inner cable. It's a really small screw, so make sure you keep
it, and the cap, safe.
Other models of Shimano, plus SRAM and Campagnolo might differ slightly.
Once you've done that, then you should be able to push the inner cable out through the
shifter. Make a note of exactly where you'll need to push the new one back through.
The outer cable for the front brake will also then be free. As you pull it away, make a
note as to whether or not there is a ferrule on the end of the cable as it goes into the
shifter. Then put it to one side as you can use it for a marker later to make sure the
new cable is the right length.
Next, push your new inner cable back through the shifter. Do it carefully to prevent any
chance of fraying. It might be a little finicky but once you do find the hole, it will go
through easily so there's no need to force it. Once that's done, replace the covering
cap if that's relevant to your shifters.
Now it's time to cut your new outer cable to the correct length using the old cable
as a guide. Right, here is where those extra couple of tools will come in handy. Use the
pick to open up the inner part of the outer cable that you've probably crimped when you've
cut it. then file away any sharp edges and if you need ferrules on either end, put them
on now. Before we do anything else, we want to make sure that the barrel adjuster is screwed
most or all the way in on the callipers. Then we can push the inner cable through the outer
and then slot the outer cable into the shifter. Give it a firm push to make sure that it's
properly in place. Next, place the inner cable through the barrel adjuster of the brake calliper
and pull it through until the outer cable nestles into place. We can then thread the
inner cable through the crimp part of the calliper.
What we tend to do at this point is to use one hand to manually push the brakes against
the rim and then let it move just very slightly away from the rim, then pull the inner cable
tight with your other hand and tighten the bolt down. There can be a little bit of trial
and error here, but there's no harm in loosening and then re-tightening the bolt a few times
until you've got the right feel for you at the brake lever. Now you can place the outer
cable back against the bar and tape it into place using some insulation tape. Double check
that the brake is feeling smooth and as you want it, before cutting the excess inner cable
leaving about an inch showing and crimping the cable end cap on to prevent fraying.
Finally, you can either replace the bar tape completely or re-wrap what was already there.
The process for the rear brake is very similar. Remove the bar tape, note where the outer
cables are on the bars and take the tape off which holds them in place. Undo the bolt which
holds the inner cable on the calliper, cut off any frayed cable, then remove from the
calliper. Next, remove the first piece of outer cable which goes from the frame to the
calliper, again noting whether there are any ferrules on the end. Place the outer cable
to one side.
Pull the next piece of outer cable away from the frame or frame boss, pull it from the
inner cable and put to one side. Next, if you need to, carefully remove the cap which
covers the end of the inner cables at the shifters. Thread your new inner cable through
and replace the cap. Cut the new outer cables to the same length as your old ones and then
file the sharp edges and use your pick to make sure that the inner cable will float
through. If you don't have the outer cable or are in doubt, marry it up against the frame
and make sure that it's long enough so that it doesn't affect your steering when you turn
the bars from side to side.
Thread the inner through the outer, lodge the outer in place at the shifter and place
the other end into the frame or frame boss. Tape the outer cable back into place on the
bars using some insulation tape. Thread the inner cable through the last piece of outer
cable, then the barrel adjuster of the calliper and place the outer cable into the frame or
frame boss and the calliper itself.
Finally, pull the inner cable through the crimping part of the calliper and repeat what
you did with the front brake until it's feeling just as you like it.
Cut the excess cable, crimp the end cap on and then put some new bar tape on or re-wrap
your old tape. Job done. You should now have some very new, smooth-feeling brakes.