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Jan 15, 2024

How to Properly Bed In MTB Disc Brakes

World Cup mechanic Brad Copeland says it’s one of the most overlooked bike setup

World Cup mechanic Brad Copeland says it's one of the most overlooked bike setup steps. And Matt Miller from Brake Ace says the Holy Grail for having good brakes is to bed them in properly. While the process of bedding in or burnishing disc brake pads is generally mentioned only in passing, it's clearly very important and can have a huge impact on your brake performance. Luckily the process isn't complicated and it's generally* the same no matter which brakes or pads you’re running.

I’ve collected brake bed-in instructions from six of the top mountain bike brake manufacturers and compiled them with tips from various videos and interviews published on Singletracks and elsewhere to explain the process, and to share some of the best tips. Note: I’ll be using the terms bed in, burnish, and break in interchangeably below.

At a high level, bedding in a new set of brake pads is all about transferring material from the brake pad to the rotor in a consistent manner. As Copeland explained to us, "some of the brake pad material embeds in the rotor surface and this gives the brakes more bite once the process has fully occurred; an initial cycle of medium-effort gradual stops will heat up the brakes, and begin the process of material exchange, coating the new brake rotor surface." In this video from Park Tool, Calvin Jones sums it up saying the process uses "heat through the friction of our braking to transfer some of the [brake pad] material to fill the pores of the rotor and remove any asperities."

All six of the top brake brands essentially recommend following the same basic steps*.

Shimano's instructions are among the most straightforward and simple, noting riders should "operate your brake lever with moderation, especially when you bed in the front brake." This appears to be more of a safety recommendation than anything else to avoid doing an endo during the procedure.

I’ve been running SRAM brakes for many years and after reading up on brake burnishing I have to say the adjectives they use are somewhat at odds with the other brands and even the experts. As a result I’ve likely been doing it wrong for some time now. Like Shimano, SRAM adds in a little rider safety CYA, beginning their instructions by saying "the bed-in process requires you to perform heavy braking," which could cause you to crash (emphasis mine). In the past I probably keyed into the bit about heavy braking more than I should have, despite the instructions that follow, which say to avoid locking up the wheels. SRAM instructs riders to firmly apply the brakes in step 2, and to repeat this 20 times at a moderate speed. Again, I and other riders may have keyed into the word firmly more than we should have.

Coincidentally SRAM recently released a video that includes helpful information on the bed-in process. I reached out to SRAM for clarification about the wording the brand uses in their manuals vs. the video but did not hear back as of press time.

In addition to the basic steps above, SRAM recommends increasing the speed from moderate to a "faster speed" and repeat the braking procedure ten more times, for a total of 30 times per brake.

Unlike the other brands I looked at, Magura recommends bringing the bike to a complete stop in step 2 of the burnishing procedure. They also recommend a higher speed — 30km/hr — than the other brands, and say to repeat the process at least 30 times.

The TRP instructions are almost identical to SRAM's. The brand recommends 15-20 slows from a moderate speed, followed by 10-15 slows from a higher speed.

Hayes recommends following the basic procedure outlined above, and repeating it 50 times, so plan well ahead before your first ride on a new set of Hayes brakes or pads. The brand also says to keep your speed to 15mph or less throughout the bed-in process.

Hope doesn't provide any specific recommendations in terms of the speed you should carry or the number of times the bed-in procedure should be performed. Like the others they recommend slowing the bike, but not stopping, and say the brakes will reach their full potential after bedding in and then after the first few rides.

Copeland says, "I like to ride back up to speed with light brake drag to keep them hot." In their video, Jones and Purdy have a different take, suggesting riding with the brakes wide open in between squeezes to allow the rotors to cool. Not only that, they alternatively suggest spraying the pads with water in between steps to create a slurry with the pad material. While that may sound unconventional, I found a reference to a similar procedure in a Hope user manual from several years ago saying it "helps to pour clean water over the caliper and pads whilst bedding in."

According to Magura, larger rotors need more break in time, and lighter-weight riders may be unable to properly bed in brake pads paired with large rotors.

As always, avoid touching the pad's braking surface or the rotors to avoid contamination before or after bedding them in, as this can significantly degrade performance.

Why do brakes need to be broken and bedded in?

Magura explains it best: "During the break-in phase, the smallest imperfections are ironed out to create the optimal friction surface between the pads and rotors. Additionally, bedding-in your pads removes any residue of the manufacturing process from the brake pads. Optimal performance and durability are only reached after the break-in phase has been completed and both the pad and rotor surfaces are fully in tune."

Does breaking in brakes make a big difference?

While the procedures for bedding in brakes may differ slightly, all of the brands agree it's an important part of maximizing brake performance. Hayes says, "Hard braking before proper burnish can result in a reduction in brake performance." TRP notes "Bedding in your new pads and rotors is critical to the performance of the brakes. Properly bedding in your pads and rotors will ensure the highest performance and best operating conditions."

How many times should I repeat the process?

As noted above, each brake manufacturer has a slightly different recommendation, though on average most agree it takes about 30 cycles to properly burnish a brake.

Why shouldn't I come to a complete stop while bedding in disc brakes?

Magura notwithstanding, TRP explains coming to a complete stop "can lead to uneven pad material deposition and can affect the performance of the brakes while riding." In the Park Tool video linked above you can even see how the brake material accumulates unevenly in hard braking.

How do I bed in rim brakes?

Good question! This article is focused on disc brakes specifically, and the procedure for rim brakes is not the same. Rim brakes are more complicated due to differences between rim braking surfaces, materials, and shapes.

*See brand-specific notes and tweaks listed below the basic instructions.