Parts of a Bicycle Brake – Rim, Caliper and Disc Labeled

All 17 parts on the diagram

Show the list

Rim brake 11

Brake lever Squeezing it pulls the brake cable. On a hydraulic brake it pushes fluid down the hose instead.
Brake pads Friction between the pads and the rim slows the wheel. They are also called brake shoes, and they wear thinner with use.
Brake arms Each arm pivots on a boss below the rim. When the cable pulls, the arms swing in and carry the pads to the rim.
Brake cable Pulling it draws the two arms together. Mechanics also call it the inner wire.
Cable housing One arm of a linear-pull brake holds the housing, through the noodle. The cable is fixed to the other arm.
Barrel adjuster Turning it out takes slack out of the cable. Turning it in gives more slack. Some brakes have one at the caliper too.
Noodle It turns the cable sideways toward the other arm. The housing comes down from above. The noodle unhooks from its arm to let a wheel out.
Boot (bellows) It sits on the cable at the end of the noodle. It is pulled back first when the noodle is unhooked.
Pinch bolt (anchor bolt) It is tightened on the cable once the slack is drawn out. It is also called the anchor bolt.
Brake bosses Frame fittings, one on each fork leg, below the rim. They are also called braze-ons.
Centering screws Each one sets the tension of its arm's spring. Turning them moves the arms until both pads sit the same distance from the rim.

Caliper brake 2

Center bolt On a single-pivot side-pull brake both arms turn on it. It sits above the wheel.
Quick release It is closed for riding. Undone, it lets the pads sit farther from the rim.

Disc brake 4

Rotor It turns with the wheel. The pads squeeze it, so a disc brake does its braking at the hub and not at the rim.
Caliper It is fixed to the frame or the fork. Inside, one pad sits on each side of the rotor.
Hose On a hydraulic brake it is full of fluid. The fluid carries the push from the lever to the pistons. A mechanical disc brake has a cable instead.
Pistons Fluid pushes them, and they push the pads onto the rotor. On many brakes the pistons keep the gap the same as the pads wear.

How this list was compiled: Part names checked on 2026-09-30, a name kept only when two of these use it for the part. (1) Wikipedia, text only: Bicycle brake (brake lever, cable and housing, noodle, bosses, brake pads, rotor, caliper, pistons, hydraulic hose, quick-release). (2) Park Tool repair help: Linear Pull Brake Service, https://www.parktool.com/en-us/blog/repair-help/linear-pull-brake-service (arms, noodle, pinch bolt, barrel adjuster, centering screws, braze-on); Dual Pivot Brake Service, https://www.parktool.com/en-us/blog/repair-help/dual-pivot-brake-service (center bolt, quick-release, barrel adjuster, pinch bolt); Mechanical Disc Brake Alignment and Hydraulic Disc Brake Alignment, https://www.parktool.com/en-us/blog/repair-help/mechanical-disc-brake-alignment and https://www.parktool.com/en-us/blog/repair-help/hydraulic-disc-brake-alignment (rotor, caliper, pads, hose, pistons). (3) Sheldon Brown's site: Adjusting Direct-pull Cantilever Bicycle Brakes, https://www.sheldonbrown.com/canti-direct.html (boot, noodle, brake shoes, bosses, spring tension screw); Installing and Adjusting Caliper Brakes, https://www.sheldonbrown.com/calipers.html (centerbolt, anchor bolt, adjusting barrel, inner wire); Bicycle Disc Brakes, https://www.sheldonbrown.com/disc-brakes.html (rotor, caliper, pads). Licence: own work

The drawing: Drawn for this site on 2026-09-30 from plain geometry, a composite of no one make; nothing traced. Licence: own work

How it works

A bicycle brake has a lever for the hand, a cable or hose that carries the pull, and a mechanism at the wheel. These drawings name the parts of a bike brake on a rim brake, a caliper brake and a disc brake.

Read the full guide

Follow the pull from lever to pads

Squeezing the brake lever pulls the brake cable through its housing. On a linear-pull brake the housing ends at the noodle, a bent metal tube on one arm, and the bare cable runs on to the pinch bolt on the other arm. The pull draws the two arms together, and the brake pads press on the rim.

Three brakes, three views

The first view is a linear-pull rim brake, often called a V-brake, with the wheel cut through so the rim shows under the tire. The second is a side-pull caliper brake from the front, the kind on road bikes. The third is a hydraulic disc brake: fluid in a hose pushes pistons, and the pads squeeze a rotor on the hub.

Turning the barrel adjuster out takes slack out of the cable, so the pads sit closer to the rim.
To take a wheel off, the noodle unhooks from its arm and the pads open wide enough to clear the tire.

Questions and answers

What are the parts of a bicycle brake called?

On a rim brake: brake lever, barrel adjuster, cable and housing, noodle, brake arms, pinch bolt and brake pads. A disc brake has a rotor on the hub, a caliper with pistons and pads, and a cable or hose from the lever.

What is the noodle on a bike brake?

A rigid metal tube with a bend, used on linear-pull brakes. The cable housing comes down from above and ends at the noodle, which turns the cable sideways so it can pull the two arms together.

What is the difference between a rim brake and a disc brake?

A rim brake presses its pads on the rim of the wheel. A disc brake has a metal disc, the rotor, fixed to the hub, and a caliper on the frame or fork squeezes pads onto that rotor.

What do the small screws on V-brake arms do?

They are centering screws. Each one changes the tension of its arm's spring, and the arms move together when either is turned, until both pads sit the same distance from the rim.