CARE FOR YOUR BRAKES
Disc brakes have long been popular on mountain bikes, and are now on more and more road bikes too. To make sure yours stay in good working order, we have put together these eight tips and maintenance pointers
(01) REPLACING PADS
Replace pads when they’ve worn to less than 2mm thick. Remove the wheel and ensure the calliper is clean and free of oil. On hydraulic systems gently pry the pads open with a screwdriver or tyre lever to fully retract the pistons. Remove the retaining pin (split pin or threaded) using pliers or a hex key. Remove the old pads and return the spring. Clean off any remaining dirt before inserting new pads and spring. Reinstall the retaining pin.
(02) LINE UP
When refitting your back wheel, setting your gears into the big ring and small sprocket should make it easier to line up the rotor between the pads. On hydraulic systems, when wheels are removed for transport or service, hold the pads open with a plastic wedge to prevent them from getting pushed together. Take care to route the front cable correctly and keep it clear of the tyre.
(03) ON THE LEVELS
Check the fluid levels on standard hydraulic systems where applicable. The types of fluid are usually marked on the reservoir cap. Shimano and Magura use mineral oil; Tektro, Formula, Hayes, Hope and Avid use Dot 4 or 5.1. Check the hydraulic line coupling bolts and nuts at the brake levers as well as where they enter the calliper. Nip them up with an open end spanner (usually 8 or 10mm).
(04) RINSE AND ROUGH EN
Overspray from lube and cleaning agents can contaminate pads, causing loss of bite and squealing. Wash with a mild soap and water solution to remove oily residues, rinse with fresh water and wipe clean. Deglaze the surface of the rotor disc by roughing it up with fine sandpaper or emery cloth. Lightly contaminated pads and rotors can be rejuvenated with Finish Line’s Speed Bike Degreaser.
(05) ROTOR RIGHT
Spin the wheel and check the rotor from above for straightness, noting any section you want to straighten. A disc truing tool consists of a slab of steel with a slot cut into it, so an adjustable spanner does equally as well. Position the jaws in the middle of the area needing to be straightened, and gently pry in the correct direction. A rubber mallet will work, but go easy with it. Spin the wheel and repeat as necessary.
(06) CENTRE STAGE
A misaligned calliper, which makes the pads strike at an angle, will cause squashy feeling brakes. Pads should be parallel as they clamp the rotor. Use thin shim washers to correct, available from a number of suppliers. Back out the bolts individually and slip in the required washers. Callipers on forks with forward-facing mounts have elongated holes offering lateral adjustment. Loosen bolts just enough, centre, and retighten.
(07 ) WASHER A ND SE T
On cable systems with concave and convex washers (Avid), squeeze and hold the lever firmly, then loosen the calliper retaining bolts with your other hand, allowing the washers and calliper to reset. Retighten bolts. On hydraulic callipers, remove the wheel and completely retract the pads. Reinstall the wheel, and with the calliper centred over the rotor, squeeze and release the lever a few times to reset the pistons and pads.
(08) PULLING POWER
To maximise pulling power you need to set up the cable correctly at its anchor point on the calliper lever: when the pads are in contact with the rotor, the angle formed by the cable and lever arm should be around 90 degrees, as illustrated above. Use the pad position dials on the calliper to move the brake pads closer to the rotor, rather than relying on cable barrel adjusters to tighten up the brakes.