Brakes make randomness for any one of several reasons, most of them bad. When we pulled apart my friend ’ s bicycle belated, we found the braking material worn down to the shoe, creating dangerous metal-on-metal military action. He needed new brake pads .
This rectify speculate might seem building complex, but it ’ south actually relatively promptly once you understand the steps. Changing them out takes just ten to 15 minutes, without much in the means of specify tools. here ’ s how to do it.
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Glossary of Bike Parts and Terms
- Wheel skewer or thru-axle: A threaded rod that attaches the wheel to the bike, often with a quick-release lever that pivots to tighten the wheel in place.
- Dropouts: The slotted section of the frame and fork where the wheels attach.
- Brake block: A small plastic shim that inserts into the caliper while the wheel is off to hold the brake pads apart if you pull the brake lever.
- Pistons: In a disc-brake system, this is the flat, cylindrical element inside a caliper that presses the pads against the rotor when you pull the brake lever.
- Brake caliper: A metal structure attached to the bike frame that straddles the braking surface and contains the pistons and brake pads.
- Disc rotor: A flat steel disc attached to the hub that is the braking surface in a disc brake system.
- Brake track: The section of the disc rotor (or wheel rim, for rim-brake systems) where the brake pads make contact.
- Brake shoe: The metal holder for the brake pad.
- Rotor bolts or centerlock ring: Disc rotors attach to the hub with either six bolts or a large lockring that threads into place.
- Barrel adjusters: On cable-activated brakes, these small cylinders at the caliper can micro-adjust cable tension.
- Lever throw: How far the brake lever moves before the pads contact the braking surface.
Step 1: Remove the wheel
For disc brakes
open and unthread the thru-axle and slide it out of the hub, then lower the wheel out of the dropouts. note : never pull a hydraulic phonograph record brake pry without a rotor or brake block between the pads. Doing then can cause the pistons to pop out of their seals. At minimum, this makes the pistons hard to re-seat. At worst, it means a major brake service job .
For rim brakes
For rear wheels, shift the gears to the smallest cog, which makes it easier for the wheel to slip past the rear derailleur cage on removal and re-installation. Open the quick-release skewer. The bicycle should drop out ( you might have to jiggle it a bite ). If you ’ ra working on your front wheel, unthread the skewer en opposite the pry just enough to get the wheel out of the dropouts. You may need to open the brake caliper with a small lever ( Shimano/SRAM ) or button ( Campagnolo ) .
Step 2: Inspect the system. (Repeat this every few weeks to check for wear.)
Tools: Flashlight, Vernier calipers for measuring rotor width ( disc only )
When there ’ s one millimeter or less of brake pad fabric left, it ’ south meter to swap. other revealing signs that you ’ re in need of fresh pads are scoring or grooves on the flange or magnetic disk rotor, which indicate something is gouging the brake track—either debris in the pad or a pad worn down to the metallic element brake shoe. Rotors don ’ t wear adenine quickly as pads, but they do finally wear out. substitute rotors when they are less than 1.5 millimeters thick at the brake track, or if they ’ re perceptibly damaged or warped .
Most rim brake pads feature a directional indicator at the lead of the pad, which doubles as a wear indicator. Most brake pads will besides have vertical slotted lines that fill the lapp routine. If you can no farseeing read the indicator, or if the slot no longer show on the braking face of the pad, it ’ randomness fourth dimension for new ones .
Step 3: Remove the pad retention screw or bolt
Tools: Needle-nose pliers, flat head screwdriver, or hex wring ( normally three-millimeter )
many disc brake pads are held in place by a horizontal screw or bolt. Some systems use magnets alternatively. The screw threads into the caliper, and/or is held in position by a cook pin or circlip. Use the pliers to carefully remove the pin or circlip if it has one, then unthread the screw or slide the bolt and remove .
You ’ ll frequently see a modest fixed fuck on the side of the brake shoe. Unthread it, but don ’ t remove entirely—just back it out adequate that you can start to wiggle the slog in the shoe. Older systems may have a fall that needs to be pulled out alternatively. If there ’ s neither, the pad just slides out. note : The rim-brake instructions here are merely for swappable pads in systems that have freestanding brake pads and shoes. Some cheap brakes feature one-piece shoe/pads that must be unbolted .
Step 4: Remove the used pads
Tools : Pliers, possibly
Disc brake pads typically have a yellow journalism on the back of each embroider to remove them. Often, pads are loosely set in a thin alloy inning ; take care not to drop it as you remove the pads. Magnet-style pads don ’ t have the human body. With fingers or pliers, cautiously grab the belittled yellow journalism on the backs of the pads, pinch them together and gently but firm pull the pads—and spring, if applicable—out of the caliper and set aside .
once the stage set screw is backed out enough to allow the diggings to move, gently push the pad out of the brake shoe. Pads always remove toward the rear of the bicycle .
Step 5: Clean and inspect the brake
Tools: Clean tabloid, rubbing alcohol, flashlight, piston press or other broad, flat tool
Use the flashlight to inspect the at heart of the caliper. You ’ ll see two ( or sometimes four ) flattish cylinders inside, sometimes with a stubby mail in the center. These are the brake pistons, which move the pad back and away. Disc brakes self-adjust for slog wear, so the pistons may need to be re-seated. With a piston press ( or any early broad, bland creature like a tire lever ), cautiously press each piston binding into the caliper body. If the pistons are truly dirty or muggy and wear ’ triiodothyronine want to re-seat, you might need to bleed the system ( motorcycle shops will do this for you ) and clean the pistons, but that ’ s a subject for another day .
Use a cleanse rag and rubbing alcohol to wipe down both brake tracks of the phonograph record rotor. Don ’ thyroxine touch the rotor ’ s brake path with bare hands ; skin oils can contaminate the arrangement. This is a beneficial time to check the rotor bolts or the Centerlock fastening ring to ensure constriction .
Inspect the brake traverse on the bicycle rim. Gouges and grooves are signs of some foreign corporeal in the embroider. Swapping pads should solve this, but you can besides wipe down the flange with a clean annoy and rubbing alcohol. On carbon paper fiber wheels, pay close care to damage like split carbon fibers, deep gouges, or early signs of potential structural damage to the carbon. Take the wheel to a shop for inspection if you ’ ra concerned. On metallic element rims, you can use fine-grit emery paper or a special brake clean block to lightly backbone out the condom and scandal deposits from the rim, then wipe it clean with a tabloid and alcohol. This will besides improve your braking power .
Step 6: Replace the pads
Tools: Pliers, and latex or any clean gloves
wear gloves. Skin oils will contaminate disc brake pads and cause noisy braking with decrease exponent. Unpack the fresh brake pads and their spring, if applicable. Slide the pads and spring into the caliper ; you ’ ll feel them seat in place, although there may not be an audible snap. Replace the horizontal retentiveness screw or bolt and, if applicable, the repair pin .
When replacing pads, note that they come in two different materials : resin/organic or metallic. If you like how your brakes perform, you ’ ll want to stick with the same material as your existing pads. Resin/organic pads, which use a mix of materials like rubber, kevlar, and carbon paper, are what most bikes come with. They ’ re generally quieter and have better transition, but wear faster, particularly in wet conditions, and can lose baron during elongated hard brake. Metallic, or sintered, pads hold exponent better under sustained brake and won ’ metric ton wear down adenine much in mire, but they ’ rhenium noisy, don ’ t have arsenic much initial sting, and tend to grind through rotors more promptly. Use metallic brake pads if you feel your brakes are fading on long descents or notice excessive wear from riding in wet conditions .
Check the peak of the pad for brake management indicator ( there are lefts and rights ). Slide the pad lightly into the brake shoe. As it gets deeper in the shoe, you may need to use more coerce to get it to amply seat. Thread the set screw back in to anchor the pad in put .
Step 7: Re-install the wheel and bed in the rotors
Tools: For magnetic disk systems, possibly a tire lever or flat-blade screwdriver
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Re-seating the pistons ( step five ) doesn ’ thyroxine always in full work. sometimes, the pads will be tight around the rotor when you re-install the steering wheel. If therefore, squeeze the brake lever several times to see if the pistons retract. Spin the roulette wheel. You ’ ll hear the pads brushing the rotor if they ’ re still excessively conclusion, and there won ’ metric ton be much lever throw before the brake engages. If this happens, remove the rack and insert a tire lever or flat-blade screwdriver in the caliper between the pads. Carefully press each embroider back into the caliper body to re-seat the pistons .
Any prison term you change pads, particularly if you swapped between organic and metallic, it ’ s a well theme to “ bed in ” the rotors to the fresh pads. This is a fancy terminus that just means devising sure adequate launching pad material has evenly transferred to the rotors so braking is fluent, herculean, and free of vibration or make noise. On your street, pedal up to 10 miles per hour, then brake on merely one lever with gradually increasing force. Don ’ thymine issue forth to a complete stop consonant. Do this five to 10[[ten]] times each for the front and rear brake. then do the lapp serve pedaling up to 15 to 20 miles per hour. You should feel the initial brake baron increase with each repeat .
As with phonograph record, if your honest-to-god pads were worn, the brakes may drag or feel besides tight now with raw, full-thickness pads. First, remember to close the quick-release on the brake caliper to bring the pads closer to the rim, and check that the brake shoe is by rights positioned. The pad should firmly contact the rim brake track, without extending off the bottomland of the bracken track or touching the run down when you pull the bracken lever. The pad should besides contact the brake track evenly top to bottom. It ’ south OK ( preferable, even ) to have the front of the pad touch the rim slenderly before the rear. This is called toe-in, and helps prevent shuddering and braking noise. If the pad is properly aligned and the system is dragging, check your barrel adjusters, barely above the caliper. After two full counterclockwise rotations, check the brake lever throw again. Keep going until the pads don ’ t drag on the rim and the lever confuse is where you want it. If the barrel adjuster is in full backed off and it ’ s still besides tight, you may need to adjust brake cable tension at the cable fixing bolt on the caliper .