Replacing a brake cable is an essential task to prevent lasting damage to the shifter.
Shifting with worn or corroded cables will place additional strain on the shifter’s internal mechanism. A cable that splits while in situ can be extremely difficult to remove.
We caught up with Jon Hayes, mechanic at independent bike shop, Ride, for the latest in our series of video guides to bicycle maintenance.
Jon begins by cutting the end cap from the existing cable, and loosening the 5mm allen bolt that holds it in place.
Once the handlebar tape has been removed (see our video on wrapping bar tape here), cut through the PVC tape that holds the cable outer to the bar. Discard the outer if worn, and pull the inner from it for inspection.
Discard the worn inner, and feed its replacement through the lever. “Good quality cables will make a massive difference to how the whole system feels,” Jon says. He uses those from the original manufacturer.
Jon opts to use a new section of outer cable, as well as a new inner. He judges the length of the outer by holding it against the handlebar, and ensures he has enough to create a smooth curve to prevent unnecessary friction. Having judged the required length to the brake caliper’s adjustment barrel, he marks the outer with his finger nail, and trims it accordingly, using sharp cutters to avoid creating a ‘burr’ at the end of the outer.
He feeds the inner cable inside the outer casing and seats the newly-trimmed outer into the housing inside the STI lever. Jon cautions against pulling the inner cable roughly into place, which risks creating unnecessary kinks in the cable.
With the new cable in place, it’s time to add a wrap of PVC tape to hold the brake cable outer tight against the handlebar. “Just a couple of turns over is all it takes,” he advises.
He holds the brake pads against the wheel rim and tightens the pinch bolt before checking the function of the cable. Jon rectifies the short lever travel caused by having ‘unwound’ the barrel adjuster when removing the old cable by winding it back ‘in’.
“All that’s left to do now is cut the cable and cap the end,” says Jon, before doing just that, trimming the cable with sharp cutters and crimping the cap to hold it in place.