Repair guides › Brakes
Replace rim brake pads
A caliper that bolts through the fork crown or rear brake bridge and reaches around the tire to squeeze pads on the rim. Standard on road bikes before discs. Two arms on two pivots pull together when the cable tightens. A quick-release lever on the caliper opens it to remove the wheel, a barrel adjuster sets cable tension, and a small screw on top centers it. Pads are usually cartridges: a metal holder with a slide-in insert.
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Tools
- Ball-end hex key set (1.5–10 mm): Park Tool HXS-1.2 Professional L-Shaped Hex Set ($$)
- 1/4" click torque wrench (about 2–17 Nm) + bits: Pro Bike Tool 1/4 inch drive click torque wrench set (2.2–16.9 Nm) ($$)
- Shop rags + nitrile gloves: shop towels and nitrile gloves ($)
- Isopropyl alcohol 91%+: isopropyl alcohol 91% ($)
- Metric combination wrenches 8–17 mm: TEKTON 14-pc metric combination wrench set 6-19 mm ($$)
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Steps
- Check the wear line or grooves on each pad. Replace when the grooves are almost gone (about 1 mm left), or if the pad is hard, cracked or has metal bits stuck in it.
- Match the pad type (see the pad diagram): threaded post with a nut (V-brakes, U-brakes), smooth post with an eye bolt (cantilevers), road cartridge (holder plus slide-in insert) or short threaded road pad (side-pull calipers). Left and right pads are often marked; the closed end of a cartridge faces forward.
- Remove the old pad, keeping the curved washers in the same order: they let you angle the pad.
- Fit the new pad loosely. Squeeze the brake so it sits flat on the rim's braking surface, about 1 mm below the top edge, never touching the tire.
- Toe-in: the front of the pad touches the rim first, about 1 mm ahead of the back (a folded business card behind the pad's tail helps). This stops squeal.
- Tighten the pad nut or eye bolt (about 5–8 Nm) while holding the pad still. Re-check that it did not twist.
- Wipe the rims with isopropyl alcohol and reset cable tension so the lever stops well before the bar. Test both brakes before riding.
Torque
| Fastener | Torque |
|---|---|
| Pad nut / eye bolt | 5–8 Nm |
Diagram
Close-up of the partsRim brake pads
Signs it needs doing
- One pad rubs (off center)
- Squeal (glazed pads or no toe-in)
- Lever comes close to the bar (pads worn or cable stretched)
- Weak in the wet (normal for rim brakes: use salmon-colored pads)