When and How To Improve Braking and Shifting Performance
Dirt, water, road salt and other junk tends to get "sucked" into protective cable housing segments (the protective, plastic jacket that surrounds the steel cable) over time, causing steel cables to become rusted or frayed. As a result, your brakes will feel gritty and rough; gear shifting will also take a hit in performance and reliability. When you notice these problems it's time to replace brake and gear cables and housing. Here's how:
Before You Begin
Brake and gear housings are different. Brake housing is made from a single flattened and coiled piece of wire. Cut ends usually have sharp burrs that need to be filed. Gear housing is comprised of many pieces of small-gauge wire that run lengthwise. Gear housing ends do not need filing.
Cut new cables and housing to match the old lengths. They should be long enough to allow the handlebar to turn from side to side without interference. If the ends of any old housing pieces are bent, add another inch or two when cutting a new piece. The bend may have occurred because the old piece was too short.
Before removing old cables and housing, notice the path by which they are routed on or through the bike's frame, brakes, levers and derailleurs (this varies on some bikes) and how cables attach to shifters (varies by component specification), so new components can be correctly installed. top of page
Brake Cables and Housing
Using a hex wrench (sizes may vary, but 5mm is the most common), loosen the front and rear brake-cable pinch bolts, take off the end crimps and slide out the cables. Remove the cables and housing.
Before installing new housing, turn the brake barrel adjusters (either on the levers or the brake-caliper arms) in all the way, then back them out three turns. This provides cable-tension adjustability should it be necessary later. Also, drip a small amount of oil, such as Boeshield T-9 Drip Lube , inside both ends of the filed housing then finish off by attaching end caps.
Install housing, then insert new cable starting at the lever, making sure that when you reach the caliper you run it along the groove on the arm and underneath the pinch-bolt washer. (If the cable is attached incorrectly, it could slip under heavy braking.) Pull the cable through the pinch mechanism until each brake pad clears the rim by about 1mm, then secure the pinch bolt. If a little more clearance between the pads and rim is desired, turn the barrel clockwise one full turn. Finish by attaching cable crimps. top of page
Gear Cables and Housing
Shift each derailleur to its easiest gear. Using a hex wrench, loosen the pinch bolts and slide out cables the same way you did for brake cables. Remove the gear cables and housing from the bicycle.
Install new cables and housing, feeding the cable through starting at the levers.
Once new cables and housing are installed, adjust derailleurs using the
barrel adjusters either on the shift levers, arms or cable stops on the
down tube. To adjust the rear, pedal and shift the chain to the big chainring,
click the rear shifter to the second gear and watch for the chain to move
one cog. If it doesn't, turn the barrel counterclockwise for more cable
tension. If it jumps two cogs, turn the barrel clockwise to loosen tension.
The front derailleur cable usually requires more tension than the rear.
Shift the chain to the small or middle ring and largest rear cog. Turning
the barrel counterclockwise, tighten the cable until the inner cage plate
rubs the chain, then undo the last turn on the barrel to eliminate the