New brake pads and rotors need to go through a wearing-in process called “bedding” before they can be used properly. Brake and pad manufacturers publish their own very similar pad bedding protocols and expect you to do this every time you install new pads and rotors.
Unfortunately, many mountain bikers don’t bed-in their brakes properly.
Properly bedded pads are key to a happy bike, happy rider and a setup that works as intended. PC Tyler PerrinIn general, all pad bedding recommendations call for a series of even and controlled brake events. During these, the brake pads are bed-in to the rotor by creating a transfer layer from the pads to the rotor through a process called thermal decomposition. Since brakes convert your kinetic [moving] energy to heat, brakes that are evenly cycled in a controlled manner are expected to apply an even transfer layer to the disc, resulting in the best braking possible for your setup.
Skipping the proper bed-in process can lead to lousy stopping power, damage to the pads and rotor, inconsistent bite or feel of the brakes, and noisy braking.
We did a survey on our Instagram and found that only 50% of respondents follow the manufacturer's bedding procedure every time they install new pads or rotors, with 31% only sometimes, and 19% not even caring enough to know what bedding is or does.
Most surprising of all was that 57% of respondents have bed-in their new pads simply by riding them down the trail! In terms of braking science, this is the antithesis of performance since uneven terrain and variable braking could lead to uneven bedding.
Do riders properly bed-in brakes? Kind of. Have they ever bed-in new pads down the trail? Uhm, yes....Given the widespread practice of skipping proper pad bedding and opting for trail-based bed-in methods, we decided to delve into the braking data. Our objective was to compare the braking during regular trail riding with braking during a controlled bed-in procedure. The aim was to identify any potential issues that riders who choose the trail method might face, and ultimately to see if there is indeed an easier way.
To get started, we installed BrakeAce PF2 wireless brake sensors on the front and rear brake mounts of a Giant Reign Advanced 29er. Brand new Magura Storm HC rotors in 203mm were installed, and Radic Kaha brakes were mounted with organic pads. Braking data was recorded wirelessly using the BrakeAce app.
Tires were relatively new Maxxis 2.5 Assegai/2.4 DHR combo, in 3C compound. The bike also had a crank-based Quarq power meter which was recorded onto a Wahoo ELEMNT.
The testing setup: Radic Kaha brakes with new organic pads mounted to BrakeAce PF2 brake sensors front and rear. Totally untouched rotors.Nothing like some freshies! We cleaned the new rotors with IPA, and apart from centering the caliper, didn't use the brakes at all until we started recording.THE PROCEDUREWe followed Radic’s pad bedding procedure which called for us to accelerate up to moderate speed and brake moderately 20 times with each brake, and then to brake harder 10 more times from a higher speed. No skidding or braking to a stop were allowed. We did exactly this, and for the “harder” brake events, we simply used both brakes. (As you’ll see, we lost count a bit and did some extra braking).
Brake pad bedding procedure from RadicWe did all testing by riding back and forth across a relatively flat, paved carpark in Rotorua, New Zealand. It was a dreary day with light mist and 16°C temperatures - maybe not ideal bedding conditions, but this certainly created a real-world scenario.
The entire bedding-in ride took 12 minutes, and 3.5km of ground was covered.
All up, 62 brake events were completed during the bedding procedure. These 62 brake events absorbed 80kJ of energy over 1:52.4 of total brake time. The average brake event was 1.8 seconds long with an average power of 712W.
Event-by-event analysis showed us that the first rear-only event had an average brake power of 549W for 1.2 seconds, but increased to over 700W for 1.7 seconds by the 20th rear-only event. The same story was true for the front brake, with events increasing from 449W for 0.4s to 687W for 1.7s later on. In the final events with both brakes, total brake power increased to over 1,000W with a slightly higher bias towards the front brake.
Across the whole ride, Brake Balance was 53% (rear)/47% (front), and estimated max rotor surface temperature was 130°C(rear)/105°C(front). Toasty!
Braking data from the BrakeAce app after following manufacturer's ped bedding protocol. From L-R: ride plot & map; ride braking stats; stats from one of the highest power events at the end of bedding.While it may have been possible to achieve a higher brake power in the very first event, the braking bite had what can be described as a “dead” feel, for lack of a better word. The brakes just didn’t feel like they wanted to do much. It may have been possible to simply squeeze harder to get higher power, but we weren’t explicitly heading out to ruin a set of braking bits, so we released the levers and squeezed based on feel.
Read on brakeace.com