Rear brake adjustment depends on your brake type
Most bicycles use either rim brakes (which squeeze the wheel rim) or disc brakes (which use a rotor attached to the hub). The adjustment method is different for each. Rim brakes are adjusted by tightening or loosening a cable and moving the brake pads closer to or farther from the rim. Disc brakes are adjusted by moving the caliper sideways so the pads sit evenly on the rotor. You can identify which you have by looking at the back wheel: rim brakes have pads on either side of the wheel itself, while disc brakes have a metal disc (rotor) sticking out from the hub with a caliper mounted above or below it.
Before you start, spin the rear wheel by hand and listen. If the brakes rub constantly, the pads are too close. If you squeeze the lever and the wheel does not slow down, the pads are too far away or the cable is loose. Most adjustments take five to ten minutes and require only an Allen wrench (hex key) and possibly a screwdriver.
Key Takeaways
- Rim brakes are adjusted by loosening the cable anchor bolt, repositioning the brake pads, and retightening the bolt until the pads sit evenly on both sides of the rim.
- Disc brakes are adjusted by loosening the caliper mounting bolts and sliding the caliper sideways until the rotor sits centered between the pads.
- Spin the wheel by hand first to hear whether the brakes are rubbing or too loose before making any changes.
- If the brake lever feels spongy or pulls all the way to the handlebar, the cable may need tightening or the system may have air in the lines (hydraulic brakes only).
Adjusting rim brakes step by step
Start by spinning the rear wheel and listening for rubbing. If the pads touch the rim when the brakes are not engaged, loosen the cable. Locate the cable anchor bolt — a single bolt that holds the brake cable to the brake caliper, usually on the side of the brake arm. Use an Allen wrench to loosen it about half a turn. Pull the brake lever a few times, then spin the wheel again. If the rubbing stops, tighten the anchor bolt firmly and test the brakes under light pressure.
If the brakes feel weak or the lever pulls too far before stopping the wheel, the cable is too loose. Loosen the anchor bolt again, pull the cable tight with your fingers, and retighten the bolt. The cable should have no slack but should not be so tight that the brake pads sit against the rim when the lever is released.
If one pad sits closer to the rim than the other, the brake arms are misaligned. Look for a small adjustment screw on the brake caliper (usually a Phillips or Allen screw near the pivot point). Turning this screw clockwise or counterclockwise shifts the brake arm sideways. Make small quarter-turn adjustments, spin the wheel, and check the gap on both sides. The pads should sit the same distance from the rim on both sides.
Adjusting disc brakes step by step
Spin the rear wheel and watch the rotor as it passes through the caliper. If the rotor rubs on one side, the caliper needs to move. Locate the two bolts that hold the caliper to the frame or hub — these are usually 5 mm or 6 mm Allen bolts. Loosen both bolts about one full turn, but do not remove them completely.
Squeeze the brake lever gently to center the rotor between the pads, then hold the lever in place. While holding the lever, tighten both bolts firmly. This method lets the pads find their natural position on the rotor. Release the lever, spin the wheel, and listen. If rubbing continues, repeat the process.
If the rotor still rubs after centering, the rotor itself may be bent. Spin the wheel slowly and watch where the rotor touches the caliper. If it rubs in only one spot, the rotor has a dent or bend. Minor bends can sometimes be straightened by gently tapping the rotor with a rubber mallet, but a badly bent rotor usually needs replacement. Do not attempt to straighten a rotor with a hammer or metal tool, as this can crack it.
When to adjust the brake pads themselves
Brake pads wear down over time and eventually sit too far from the rim or rotor to work well. On rim brakes, if the pads are worn down to a thin layer, they need replacement rather than adjustment. You can tell pads are worn if they no longer have a groove or texture on the surface, or if they are less than 1 mm thick.
On disc brakes, hydraulic systems automatically move the pads closer as they wear, so adjustment is rarely needed. Mechanical disc brakes (which use a cable instead of fluid) may need the cable tightened as pads wear, using the same method as rim brakes. If the lever pulls all the way to the handlebar and the wheel still does not stop, the pads are likely worn out and need replacement.
Testing your brakes after adjustment
After adjusting, spin the wheel by hand and listen for any rubbing sound. The wheel should spin freely without the brakes touching. Then squeeze the brake lever firmly — the wheel should stop within one or two rotations. The lever should feel firm and stop about halfway to the handlebar, not spongy or too close to the bar.
Take the bicycle for a short test ride in a safe, empty area like a parking lot. Brake gently at first, then harder, to make sure both brakes respond evenly. The rear wheel should lock up (skid) if you brake hard enough, which means the brakes are working. If the wheel does not slow down even with hard braking, the cable may be too loose or the pads may be worn out.
Tools and parts you may need
Most rear brake adjustments require only an Allen wrench set (typically 4 mm, 5 mm, and 6 mm sizes) and possibly a Phillips or flat-head screwdriver. A bicycle repair stand is helpful but not required — you can flip the bicycle upside down or prop it against a wall so the rear wheel spins freely. A small flashlight makes it easier to see the brake pads and rotor.
If the cable is frayed, kinked, or visibly damaged, it should be replaced rather than adjusted. Brake cables are inexpensive and come in different lengths for rim and disc brakes. If the brake pads are worn completely flat or missing chunks, replacement pads are also inexpensive and usually take five minutes to install. Most bike shops sell both cables and pads, and many will install them for a small fee if you prefer not to do it yourself.
Frequently Asked Questions
Why do my brakes rub on one side only?
The brake caliper is misaligned. On rim brakes, use the adjustment screw on the caliper to shift the brake arm sideways until both pads sit evenly from the rim. On disc brakes, loosen the caliper bolts, squeeze the brake lever to center the rotor, and retighten while holding the lever.
What if the brake lever goes all the way to the handlebar?
The cable is too loose or the pads are worn out. Loosen the cable anchor bolt, pull the cable tight, and retighten the bolt. If the lever still travels too far, the pads may be worn and need replacement. On hydraulic disc brakes, a spongy lever usually means air is trapped in the lines and the system needs bleeding.
Can I adjust my brakes without removing the wheel?
Yes. Spin the wheel by hand to test the brakes and listen for rubbing. You can make cable and caliper adjustments without removing the wheel. However, if the pads need replacement or the rotor needs straightening, you will need to remove the wheel to access those parts.
How often should I adjust my rear brakes?
Adjust brakes whenever you hear rubbing or notice the lever pulling too far. As pads wear, rim brakes may need cable tightening every few months depending on how much you ride. Disc brakes with hydraulic systems adjust themselves, so they typically need attention only when pads are worn out or the rotor is damaged.