Installing or replacing the cables on your mountain bike can do wonders to improve shifting performance on the trail and you might be surprised just how easy it is to do yourself. This article will focus mainly on derailleur cabling but many of the concepts are transferable to mechanical brakes (disc and V-brakes) for those who haven’t upgraded to hydros yet.
We’ll start with this short tool and material list:
- Cable/housing cutting tool
- Allen wrenches
- Cables and housing
Cable and housing cutting tool.
That’s it! The only tool you may not have already is the cable cutting tool and unfortunately it’s necessary – most general purpose tools won’t cut it for this job (ha!).
Choosing cables and housing
Jagwire, Gore, Shimano, and SRAM sell cable and housing kits at various price points depending on the quality of the product. In general, you get what you pay for so if you want the best cables, buy the most expensive set. That being said, performance benefits are diminishing as you move up the cost-ladder so I usually pick the middle-of-the-road cable and housing kit (around $25) to get the most bang for my buck. Note that some kits may be specifically designated as brake or derailleur cable kits so make sure you know what you’re getting. Also, most kits will include enough cable and housing for front and rear so you just need one kit for your derailleurs and one for your brakes.
If you’re only replacing a single cable or a busted housing, you don’t need a full kit and most manufacturers also sell cables, housing, and parts separately. But for a complete overhaul or new install, go with the kit because it’s cheaper than buying the parts and it’ll include all the little pieces you’ll need for a smooth installation.
Start at the shifter (or brake lever) and carefully take the unit apart. The tops on most SRAM shifters unscrew without a tool – just use your thumbnail and twist. Make a careful note of how the cable is routed inside the shifter – once you take the old cable out you’ll need to route the new cable in the same way. New shifters often come with the cable pre-installed.
The “barrel” end of a shifter cable.
Bike cables usually come with two metal ends attached – a disc on one end and a barrel on the other. In general, the disc end is needed for a brake cable install while the “ball” end is used for shifter installation. Since we’re installing derailleur cables here, cut off the disc end using your fancy cable cutters. Bike cables are actually made up of bundles of many tiny cables so you want to make sure you get a clean cut and avoid fraying the bunch – hence the need for a sharp, special cable cutting tool for the job. A frayed cable end will be nearly impossible to thread through your shifter and cable housing and once a cable starts to fray, it’s usually worthless.
Holding the cut end of the cable, thread the cable through the shifter according to the instructions that came with your shifter unit. Now relax – that’s often the hardest part of the operation!
If you’re replacing the cables on your bike, now is the time to round up the old cable housing pieces so you can cut the new cable housing to the same lengths. For a new install, start with the first section – from shifter to frame – and hold the housing between the shifter and first cable stop. Rotate your handlebars far left and far right to make sure you have enough slack for a full turning radius. Mark the spot with your finger, then make a clean cut using your tool, being careful not to crush the housing as you cut. Place ferrules on both ends of the housing, then route the cable through the housing, taking care to avoid fraying the cable. A good rule of thumb: if you feel resistance when pushing the cable through, back off and try again. If you force the cable, you’ll fray it. Sometimes twisting the cable inside the housing can overcome a slight resistance (just be sure to twist with the cable braid rather than against it).
Slip the ends of the housing into the shifter and frame stops and admire your work! For the rear derailleur you’ll need to repeat this procedure twice more, fitting the housing between cable stops on your frame. If you have a full suspension bike, be sure to leave some slack in the cable and housing in the transition between the main and rear triangles to account for travel.
If you’re installing a brake cable or if your frame uses cable guides instead of cable stops in places, just run the cable and housing continuously and use zip ties to attach the housing to the frame. Tighten the zip ties all the way down and cut off the excess as close to the guide as possible. You can also use C-clips designed specifically for attaching housing to your cable guides.
At the derailleur end, attach the cable to the anchor bolt and tune your derailleur. For the front derailleur, you may want to first add a cable “boot” for additional protection – most kits will include this and the boot will slide over the cable just like the housing. Once you have things pretty well dialed, cut off the excess cable and place an end cap over the cut end. Crimp the end cap down using your cable cutter (if it has a crimper) or use a pair of pliers. This will prevent the cable from fraying over time.
Cabling tips and tricks
Cable rub can be a problem on some bikes, particularly if you have excess housing length in certain places. On our New Year’s ride, ckdake pointed out evidence of cable rub on my new bike – and this was just the second ride! His suggestion: electrical tape on the frame between the frame and the housing. This worked great for me and since my frame is black, it’s hardly even noticeable.
Sheldon Brown mentions using a rosin-core solder on the ends of cut cables to prevent fraying and also a few lubrication strategies for keeping things rust-free and smooth shifting. Modern coated cables may not need lubrication so check the instructions that come with your your cable kit.
Properly installed, your cables and housing should last for years with little to no maintenance. But if you’re experiencing shifting problems or notice cracked housing and frayed cables, it may just be time for a simple cable overhaul.