For optimal results, new disc-brake pads and rotors should be put through a break-in process
known as (interchangeably) "bed-in", "burnishing", or "burn-in". When properly done (and
maintained) the bed-in process improves brake power, reduces brake noises, eliminates
judder (rapid alternating slip and grab, resulting in shaking, vibration, and squeal/honk), and
prolongs rotor and pad life.
Unfortunately, while disc-brake manufacturers all publish recommended bed-in procedures,
for the sake of simplicity these procedures are, at best, loose guidelines. If mechanics follow
these procedures to the letter, they may waste a great deal of time and effort, the results could
fall short of accomplishing bed-in, or the results could be badly overheated brake-system
components that are more likely to produce the very symptoms that bed-in should prevent.
Here are some examples of manufacturer's recommended bed-in procedures:
Shimano: Clean the rotor. On pavement, get the bike up to a good speed, then firmly and
evenly apply the front brake until the bike comes to almost a complete stop. Repeat 10 times.
You should notice the brake becoming more powerful with each braking cycle. Repeat for the
Avid/SRAM: Accelerate the bike to a moderate speed (approximately 19 kilometers or 12
miles per hour), then firmly apply the brakes until you are at walking speed. Repeat
approximately 20 times.
Accelerate the bike to a faster speed (approximately 32 kilometers or 20 miles per hour).
Then very firmly and suddenly apply the brakes until you are at walking speed. Repeat
approximately 10 times.
Do not lock the wheels up at any point during the bed-in procedure.
Allow the brakes to cool prior to any additional riding.
Hayes: Disc brakes require a special burnish period to achieve maximum braking power. The
burnish period lasts for about 30-50 hard stops. During this period some noise may occur.
Brake pads are complex structures. At the simplest level, brake pads are a combination of
abrasive particles or fibers (of various materials) bonded together by a phenolic resin.
Complexity results from the wide variety of abrasive materials and resin compounds that are
used. Additionally, variable ratios of the abrasive material to resin material exist for different
The bed-in procedure, therefore, has two purposes. First, if the brake setup has not
established perfect parallelism between the pad faces and the rotor faces, then the bed-in
process improves this conformity. However, the amount of braking necessary to produces full
conformity is a function of the initial degree of severity to which the pad and rotor faces are