One of the problems with using metal cables to control bicycle transmissions is that the weather does its best to ruin them, with water to cause rust and dirt to gum everything up. If well looked after, gear cables can last years but if you leave them to the weather, you could be fitting replacements often, which isn't cheap. If corrosion has got the better of one of your gear cables, here's how to replace it.
Our guide below shows you what we believe is the best method to refit a gear cable in a SRAM Rival hydraulic road brake/gear lever. We've included a list of the tools and materials that you will need to complete the job and in some cases where you can buy them. If there are others that you prefer then feel free to let everybody know in the comments.
Fitting a new gear cable should be pretty simple, but modern bikes with internal routing and convoluted cable runs through the components and frame can make what used to be a five minute job take a bit longer. For example, frames with internally routed cables can require removal of the cranks and bottom bracket as is the case with the bike in our example below.
Be methodical and don't be afraid to to take the long route. Some of the fuzzy logic used by the component manufacturers means some of the simple steps, like threading the new inner cable through the shifter mechanism, is a pain unless you take the shifter off the bars. So, deep breath and let's fit this new rear gear cable.
1 Unfasten the old cable Fully down shift the rear gears. Undo the rear derailleur cable anchor bolt. Unthread the inner cable from the grooves and guides that are on the rear and underside of the rear derailleur.
2 Pull out the cable Pull the inner cable out through the derailleur's barrel adjuster. If there's a protective cap crimped on to the end of the cable, a good tug at this point will pull it off.
3 Remove the lever Unwrap the tape from the right hand side of the bar. Roll the rubber lever hoods forwards as shown here and use a 5mm Allen key to loosen the retaining bolt which holds the brake lever to the bar.
4 Slide the lever off of the handlebar We do this because it is extremely difficult to thread the new inner cable through the shifter with it on the bar, a design failing of the SRAM Hydro R brake/shifter unit. I haven't quite fully removed the old inner cable here, you can do it before or after lever removal, it doesn't matter which.
5 Select the nipple Most new gear inner cables have nipples on both ends. One end is a cylinder with squared off ends (the top one in this shot), the other end is a shorter cylinder with domed ends. For Shimano and SRAM shifters we need the squared off end; the other fits Campagnolo shifters, because having the same fitting for such a common spare would be too simple. Trim the other end off.
6 Cut off the 'wrong' nipple Use the sharpest cable snips you can find. These are Park Tool CN10C Pro cutters and are the benchmark. They're ideal for trimming inner and outer cable and have shaped areas (visible below the pivot bolt at the bottom of the shot) that are great for reforming cable outer for a tidy finish.
7 Feed in the new cable With the fresh cable cut, you can feed the end into the hole in the lower inside edge of the plastic lever housing (see the bottom of the shot). It goes into a red plastic piece and up and around the ratchet mechanism, exiting the lever body through a hole in its top outside edge. There is a slot (just visible to the right of the top piece of cable) which leads to the channel into which the outer housing for the bars meets the shifter.
8 Pull the new cable through Make sure that when you reach the last bit of inner cable, that the nipple goes cleanly into the hole in the shifter body and sits fully into its seat. Without kinking the cable, give the end handing out of the shifter top, a tug just to be sure.
9 Lube the cable Grease the section of inner cable that will be under the bar tape. There are some sharp turns to make it from the shifter and around the first bend of the bar, so the grease will help mitigate the friction.
10 Replace the lever Refit the brake lever on to the bar, ensuring it's at the right height and angle. Bolt it down with the 5mm Allen key. With the run of housing ready, thread the greased inner cable through the outer. Push the outer ferrule fully home into its hole in the shifter body. Tape the gear and brake lines to the bar.
11 Thread the cable Depending on your frame you might have external cables, in which case just thread your fresh inner cable back through the stops and housing runs to the rear derailleur. Internal routing technique will vary by brand and model. This Turner Cyclosis frame uses removable panels (the black oval). In this case we just need to thread the end of the inner cable into the cable stop and through the tiny hole in its base. This will allow the inner cable to enter the down tube.
12 Route the cable through the frame Remove the bolt which retains the plastic cable guide. again frames very on how the guide is accessed, Many, like this Turner, use a simple hole in the bottom bracket shell to allow access for a long 4mm Allen key.
13 Push the inner cable fully into the downtube You'll need to poke your fingers into the bottom bracket shell and into the bottom of the downtube. There will most likely be a step edge stopping the inner cable from just poking into the BB shell. Feel around for the cable end and coax it through.
14 Thread the new inner cable through the appropriate slot in the guide, its usually the one on the right hand side (left in this picture), the centre slot is for the front derailleur cable, but as this bike is a 1x set up, there is no cable. Now the tricky bit: Pull the cable through and as you do slide the guide back up the cable and work it back inside the bottom bracket shell and into its normal position. As you do this you also need to slot the end of the inner cable up the inside of the right hand chainstay. Secure the guide with the 4mm Allen key. It takes patience of a saint and the fingers of a child to manage it cleanly. Worry not, even the best mechanics find this tricky.
15 Thread the cable through the stay The end of the inner cable is inside the chainstay. On this bike the black panel unscrews and you can pick the end out. Thread the black housing on to the cable and re-screw the housing back into the chainstay. At this point we often pull the cable tight with our left hand and operate the shifter with our right, just to check the inner cable is running smoothly.
16 Fit the last piece of outer Thread the last piece of outer housing onto the inner cable and ensure that the ferrule is seated into the stop in the chainstay.
17 Fit the cable into the derailleur Pop the end of the inner cable through the rear derailleur's barrel adjuster. This is actually quite a skill. Take care not to damage the end of the cable and cause an ugly fray. If it does, you should have enough spare cable to make a trim and go again.
18 Tighten the cable clamp Route the cable inner through the grooves and guides of the rear derailleur into the clamp. Pull the cable so that it is tight, but not so that it pulls the derailleur's parallelogram, then tighten the clamp bolt. You now need to check the indexing of the rear derailleur.