05/08/2011
The exhilarating thrill of mountain biking, whether conquering technical trails or cruising scenic routes, hinges significantly on two critical elements: speed and, perhaps even more importantly, control. While speed fuels the excitement, it's effective control that ensures your safety and confidence on the bike. At the heart of this control lies your braking system, and specifically, your disc brake pads. Often overlooked, but undeniably crucial, is the process of 'bedding in' new disc brake pads. World Cup mechanic Brad Copeland calls it one of the most neglected bike setup steps, and Matt Miller from Brake Ace hails proper bedding-in as the Holy Grail for achieving truly exceptional brake performance.
Despite its profound impact, the process of bedding in, or burnishing, disc brake pads is frequently mentioned only in passing. Yet, its importance cannot be overstated; it can dramatically influence your brake's power, modulation, and longevity. Fortunately, the procedure isn't overly complicated and, for the most part, remains consistent across various mountain bike brake systems and pad types. This comprehensive guide compiles insights from leading brake manufacturers, alongside expert advice from seasoned mechanics and industry professionals, to demystify the bedding-in process and equip you with the knowledge to achieve optimal braking on your mountain bike.
Understanding the Brake Bedding-In Process
At its core, bedding in a new set of brake pads is about facilitating a consistent and uniform transfer of material from the brake pad onto the surface of the rotor. This fundamental step is what transforms a new, raw braking surface into a highly efficient friction system. As Brad Copeland eloquently explains, “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.”
Calvin Jones from Park Tool further clarifies this, stating that 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.” Essentially, you're creating a microscopic, even layer of brake pad material on the rotor, which significantly enhances the friction coefficient and ensures consistent braking performance. Without this crucial transfer layer, the initial contact between the pad and rotor can be uneven due to microscopic surface irregularities, leading to reduced efficiency, inconsistent stopping power, and even annoying brake squeal.
The General Step-by-Step Bedding-In Guide
While specific recommendations may vary slightly between manufacturers, the fundamental steps for bedding in new disc brake pads are largely consistent across all major brands. Following these general principles will put you on the right path to optimal brake performance:
- Select a Suitable Location: Choose a quiet, smooth, and flat surface, ideally tarmac, that is free from obstacles and traffic. A moderate descent can also work, but a flat area allows for more controlled repetition.
- Accelerate to a Moderate Speed: Get your bike up to a comfortable moderate speed. This is typically around 15-20 mph (25-30 km/h). The exact speed is less critical than maintaining consistency.
- Apply Brakes Firmly (But Not to a Stop): Once at speed, apply one brake lever (either front or rear) firmly but progressively. The goal is to slow the bike down to walking speed (around 2.5-4 mph or 4-6 km/h) without locking up the wheel or coming to a complete stop. The pressure should be firm enough to generate heat and friction, but not so aggressive that it causes skidding.
- Repeat the Process: Ride back up to your moderate speed and repeat step 3. Continue this cycle for approximately 20-50 repetitions per brake. It's crucial to bed in each brake independently to ensure proper material transfer on both rotors.
- Allow for Cooling: After completing the repetitions for each brake, allow the brake system to cool down completely before your next ride. This allows the newly formed transfer layer to cure and stabilise.
Brand-Specific Bedding-In Recommendations
While the general process remains the same, some manufacturers offer nuanced advice that can optimise the bedding-in for their specific products. Here's a breakdown of recommendations from some of the leading mountain bike brake brands:
| Brand | Recommended Speed | Number of Cycles | Key Notes |
|---|---|---|---|
| Shimano | Moderate | ~20-30 | Operate lever with moderation, especially front brake, for safety. |
| SRAM | Moderate then Faster | 20 (moderate) + 10 (faster) = 30 | Emphasise 'heavy braking' but avoid locking up. Increase speed for the final 10 cycles. |
| Magura | 30 km/h (19 mph) | At least 30 | Uniquely recommends coming to a complete stop during each cycle. Higher initial speed. |
| TRP | Moderate then Higher | 15-20 (moderate) + 10-15 (higher) | Similar to SRAM, avoid complete stop. |
| Hayes | 15 mph (24 km/h) or less | 50 | Focus on consistency and a higher number of repetitions. |
| Hope | Not specified | Not specified | Slow bike, but don't stop. Full potential reached after bedding-in and first few rides. |
Shimano's Approach
Shimano's instructions are known for their clarity and simplicity. They particularly advise riders to “operate your brake lever with moderation, especially when you bed in the front brake.” This is primarily a safety recommendation, aimed at preventing an accidental endo during the procedure, which is a sensible precaution given the heat and friction involved.
SRAM's Nuances
SRAM's recommendations have, in the past, caused some confusion due to their strong language. They start by stating, “the bed-in process requires you to perform heavy braking,” which, when taken out of context, might lead riders to brake too aggressively. However, they immediately follow this with instructions to avoid locking up the wheels. SRAM suggests firmly applying the brakes for 20 repetitions at a moderate speed, then increasing to a “faster speed” for an additional 10 repetitions, totalling 30 cycles per brake. The key here is 'firmly' rather than 'heavy' to avoid skidding.
Magura's Distinct Method
Magura stands out from the other brands by recommending that you bring the bike to a complete stop during each cycle of the burnishing procedure. They also suggest a slightly higher initial speed of 30 km/h (approximately 19 mph) and advise repeating the process at least 30 times. This unique approach highlights that while the core principle of material transfer is universal, the exact methodology can have brand-specific variations.
TRP's Detailed Steps
TRP's instructions closely mirror those of SRAM. They recommend 15-20 slowdowns from a moderate speed, followed by 10-15 slowdowns from a higher speed. Like most other brands, they advise against coming to a complete stop during the process to ensure even material deposition.
Hayes' Thorough Protocol
Hayes provides a clear and consistent recommendation, advising riders to repeat the basic bedding-in procedure a substantial 50 times per brake. They also specify keeping your speed at 15 mph (24 km/h) or less throughout the entire process. This indicates that Hayes prioritises a longer, more gradual bedding-in period for optimal performance.
Hope's General Guidance
Hope's recommendations are less prescriptive regarding specific speeds or number of repetitions. They generally advise slowing the bike without coming to a complete stop and note that their brakes will achieve their full potential not only after bedding in but also following the first few rides, suggesting a gradual improvement over initial use.
Additional Tips and Tweaks for Optimal Bedding-In
Beyond the fundamental steps, experienced mechanics and riders offer several valuable insights that can further optimise the bedding-in process and ensure the longevity and performance of your brakes.
- Managing Heat: There are differing schools of thought on heat management during bedding-in. Brad Copeland suggests riding back up to speed with a light brake drag to keep the pads and rotors warm, facilitating continuous material transfer. Conversely, Calvin Jones and Truman Purdy from Park Tool recommend riding with the brakes wide open between applications to allow the rotors to cool. They even propose an unconventional method: spraying the pads with water between steps to create a slurry with the pad material, which helps in the transfer. Interestingly, an older Hope user manual also referenced a similar procedure, suggesting pouring clean water over the caliper and pads during bedding-in. The key is to manage heat effectively to prevent overheating but also to ensure enough heat for material transfer.
- Rotor Size and Rider Weight: Magura highlights an important point: larger rotors generally require more break-in time due to their increased surface area. Furthermore, lighter-weight riders may find it more challenging to properly bed in brake pads, especially when paired with large rotors, simply because they generate less heat and pressure during braking. This might necessitate more repetitions or slightly firmer braking.
- Preventing Contamination: This is a critical rule for any brake maintenance. Always avoid touching the brake pad's braking surface or the rotors with your bare hands, or allowing them to come into contact with grease, oil, or cleaning agents. Contamination can severely degrade brake performance, leading to squealing, reduced stopping power, and uneven wear. If contamination occurs, the pads may need to be replaced, and rotors thoroughly cleaned with isopropyl alcohol.
- Clean Rotors are Key: Before you even begin the bedding-in procedure, ensure your rotors are spotlessly clean. Use isopropyl alcohol and a clean, lint-free cloth to wipe down both sides of the rotor. This removes any manufacturing residues, oils, or dirt that could hinder the even transfer of pad material.
- Consistency is Crucial: Throughout the entire bedding-in process, strive for consistency in your braking pressure and speed. Erratic braking or sudden stops can lead to uneven material deposition, which can compromise performance and create hot spots on the rotor.
Why Bedding In New Brake Pads is Essential
Understanding the 'why' behind bedding in new brake pads underscores its importance. Magura provides an excellent explanation: “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.”
Without proper bedding-in, the initial contact between the brake pad and rotor is uneven due to microscopic surface irregularities. This leads to:
- Reduced Braking Efficiency: The brakes won't perform at their peak, feeling weak or inconsistent.
- Extended Pad Lifespan: Uneven wear can occur, shortening the life of your brake pads.
- Minimised Brake Squeal: Proper material transfer helps to eliminate annoying noises during braking.
A controlled, repeated braking process creates that vital, even transfer layer, resulting in smoother, more reliable, and ultimately safer braking.
Frequently Asked Questions About Brake Bedding-In
Why do brakes need to be broken in and bedded in?
Brakes need to be broken in to achieve optimal friction and performance. This process, also known as burnishing, removes manufacturing residues from the pads and, most importantly, transfers an even layer of brake pad material onto the rotor surface. This 'transfer layer' is crucial for maximum stopping power, consistent feel, and preventing noise.
Does breaking in brakes make a big difference?
Absolutely. All brake manufacturers agree that proper bedding-in is vital for maximising brake performance. Hayes states, “Hard braking before proper burnish can result in a reduction in brake performance.” TRP emphasises, “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.” Neglecting this step will leave you with sub-par braking power, increased noise, and potentially shorter pad life.
How many times should I repeat the process?
The number of repetitions varies slightly by manufacturer, but on average, most recommend approximately 20-50 cycles per brake. Many brands suggest around 30 cycles as a good benchmark to properly burnish the brake pads and rotors.
Why shouldn’t I come to a complete stop while bedding in disc brakes?
With the notable exception of Magura, most manufacturers advise against coming to a complete stop during the bedding-in process. TRP explains that coming to a complete stop “can lead to uneven pad material deposition and can affect the performance of the brakes while riding.” When you stop fully, the pad remains stationary on one spot of the rotor while hot, potentially leaving an uneven deposit of material. This can create 'hot spots' or inconsistencies on the rotor, leading to pulsing or reduced performance during subsequent rides.
How do I bed in rim brakes?
This article specifically focuses on mountain bike disc brakes. The procedure for bedding in rim brakes is entirely different due to the fundamental differences in braking surfaces, materials, and mechanisms. Rim brakes involve direct contact with the wheel rim, and their break-in process is generally less defined and more related to initial wear of the pad material against the rim.
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