Lab Reports

Gorilla Brakes & HINE-R Engineering Collaboration – Bicycle Brake Pad Testing

Carried out 8th September 2026 at ‘The Lab’, Darwen, North West England, UK

Personnel

Lee Hine of Gorilla Brakes provided all the materials for testing and was present throughout, adding his knowledge and experience of working with and selling bike brakes since 2012. His customer-focused mindset helped to bring the ‘human’ side to this test to help ensure it was as relevant as possible.

HINE-R Engineering was represented by Adam Read, previously of TartyBikes. With cycling industry experience dating back to 2001 and his general engineering background including building and racing cars, building bike frames and many other practical projects requiring a wide range of manufacturing and design skills, this allowed him to understand and consider a huge range of related aspects during testing. Adam has written this document from his perspective, with Lee’s experience and expertise also noted and included.

Aims and Objectives

To design and carry out a testing protocol to measure and record bicycle disc brake pad functionality, specifically braking power, disc rotor temperature and caliper temperature.

Testing was carried out with impartial gathering of raw data in mind, rather than trying to ensure one brand / model of brake pad ‘won’ the test. We believe it can be said that each individual rider and cycling discipline will have different preferences and suitability – for example a road bike may only have one brake application every few minutes (junctions, etc) and therefore a pad that works from cold may be best suited. A discipline such as downhill mountain biking in a location like the Alps may require a brake pad that can withstand extremely high temperatures without ‘brake fade’ (reduction of braking power), but will not be concerned with cold performance.

The main aim was to record useful data to help allow customers make more informed brake pad purchasing decisions, as well as learning about the finer points of brake systems – again allowing this to be passed on to the wider community.

Test Equipment

A custom brake testing rig built by Adam fitted to a Warco GH1232 gearbox lathe with constant speed motor, power meter to read lathe power consumption, K-Type thermocouples with skid for reading rotor temperature and surface probe for caliper body temperature.

Brake system was a Shimano M9100 lever mated to a HINE-R Wilfred caliper and HINE-R brake hose, bled with Shimano LV Mineral oil, and running on a Shimano RT86 6-Bolt rotor in 203mm diameter. We had two of these rotors available for the test, both had been used on a bike previously but with minimal miles and less than 0.05mm of wear – just enough to ensure completed bedding in.

The brake lever was operated by a fixed and known force throughout – a weight hanging from a piece of paracord, running over a roller on a dummy handlebar to which the lever was fitted, and then attached to the end of the lever blade via a 3D printed hook to ensure the force was being applied in the same location as a human finger.

The M9100 lever was chosen since it does not use the servo wave system of the higher end levers. We believed this would help with consistency of results should any brake ‘pump up’ or change of lever throw happen due to heat expansion of the fluid, affecting the mechanical advantage of the brake system and thus braking power results.

The HINE-R caliper was selected as this study was to be part of durability testing during development of the caliper.

Test Protocol Design and Considerations

We needed to develop a test protocol that gave multiple data points throughout a wide range of brake temperatures. This was tricky, as applying the brakes hard (high lever force) or for a long time per application was required to reach the fade point of some pads – but it heated the brake quickly and left poor resolution at low braking temperatures. Conversely, a protocol that allowed good resolution at low temperatures did not build sufficient brake temperature to test the high end. We had to manually switch the on/off brake application ratio at a certain temperature.

We wanted to use a cooling fan to simulate airflow over the bike while riding, but the limitations of our test equipment meant that we were unable to build enough brake temperature with the fan running, so had to test with the fan off. It was noted that this may reduce real-world significance. We were able to use the fan between tests to cool the system, however.

Bedding in of brake pads is critical to their proper function, and with brake new brake pads being used for each test we needed to design a procedure for this. Part of the bedding in process is to create a ‘transfer layer’ of brake pad material onto the rotor surface, but also to flatten off and remove surface imperfections from the pad. A third consideration for pads using resin-based compounds is to generate sufficient heat to cure these resins fully. This process can release gases from the pad and this may ‘push’ the pad away from the rotor during a braking effort, causing a notable drop in performance. This is known as ‘green fade’ and usually only happens once, but can be quite scary and cause the rider to lose confidence in the pads. We attempted to design a procedure that would ensure that each set of pads was fully bedded in before the testing begun.

Temperature of the brake caliper was logged since the NBR (Nitrile Butadiene Rubber) seals used in the brake caliper have a maximum operating temperature of around 150°C before they start to degrade. They are generally quite happy to be momentarily subjected to 120°C. We wanted to ensure we used the same brake system for all the testing to ensure consistency, so decided not to exceed this temperature.

The surface temperature of the brake rotor was logged as this is the temperature that the brake pad friction surface is operating at. We were specifically looking at braking power vs temperature so it was vital that this was logged accurately. The K-type thermocouple used was attached to a stainless steel ‘skid’ which ran against the rotor at all times. This was sensitive enough to detect the increase in rotor temperature created just from the skid itself being run against the rotor, and with a maximum temperature rating of 1200°C it turned out to be more than adequate for our testing.

A power meter was used to measure the power consumption of the lathe (in watts, or Joules per second) before each test began, without any braking effort being applied. This was the datum from which braking power was calculated. Once the brake was applied the lathe kept spinning at a constant rpm, andthe power meter showed how much power the lathe was now consuming. The difference between this value and the unloaded datum showed how much power the brake was generating.

Test Protocol

The following procedures and conditions were used:

- Before the start of each process (both the bedding in and main test protocol), the caliper was allowed to cool to below 35°C and the rotor below 30°C.

- The cooling fan was not running.

- Lathe operating at 200rpm.

- 2.3kg weight hung from the lever blade (22.5N force).

Bedding in procedure. This was carried out every time a new set of pads was fitted:

- Brake was applied in 2 second intervals, 2s on / 2s off, until rotor temperature was 150°C.

- Brake system was allowed to cool, until the caliper was below 35°C and rotor was below 30°C. From here, this will be described as ‘The Cooling Process’.

- Brake was applied in 2 second intervals, 2s on / 2s off, until rotor temperature was 225°C.

- The Cooling Process was allowed to take place.

Brake pad test procedure:

- Run the lathe without any braking load for a few seconds to allow the power meter to stabilise. The unloaded power consumption was recorded.

- Brake was applied in 3 second bursts followed by a 7 second rest.

- During the final one second time period of each brake application ‘block’, all three data points were recorded (caliper temp, rotor temp, lathe power consumption).

- This procedure was repeated until rotor temperature reached 200°C.

- After 200°C, this was switched to 7 second bursts of braking effort with a 3 second rest.

- Brake applications were continued until the caliper temperature reached 120°C.

Brake pads were then swapped out while the test kit was cooling down to the required temperatures, and the complete protocol was carried for all pads.

Extra test:

At the very end of the day, we then decided to run a test which would continue until something failed. The brake pads fitted were Gorilla Enduro Pro Ultimate (Orange).

Around 450°C rotor temperature, the Shimano RT86 buckled to the point it became unusable.

We switched out for a TRP R1 rotor in the same 203mm diameter, which continued to 650°C rotor temperature, at which point it began to glow orange.

The failure modes were as follows:

Firstly it appears that the PTFE liner on the brake hose melted at the caliper end, causing a pressure loss in the system.

After this, the continued heat soak melted the caliper seals and stuck the pistons into the caliper body. We did not notice any leaks here, however.

It was noted that there was no brake fade even at this temperature. Upon inspection after cooling down, the brake pads showed slight signs of degrading, with the very edges a little crumbly and the odd crack across the pad surface, but the main bulk of the pad was still intact and would still function well despite the extreme heat it had been subjected to.

Main Findings

It was difficult to draw detailed conclusions from our testing. There were a few factors involved, noted below, that may have affected the results. However, we learned a lot, devised plans for further testing, and some general trends have stood out. These are listed in no specific order:

- Pads with a higher metal content seem to transfer heat into the caliper faster. The sintered pads reached 120°C caliper temperature at nearly half the rotor temperature of the semi-metallic and ceramic pads, and their test had to be cut short.

- The Trickstuff Power pads, which appear to be of ceramic material, were the best at insulating the caliper (ie. they achieved the highest rotor temperature before the caliper reached 125°C).

- None of the pads exhibited any particular noise, though it must be noted that the lathe is quite loud and the skid operating against the rotor makes a high-pitched metallic sound throughout. Other noises such as resonance or vibration never occurred, indicating that perhaps these are down to brake setup / caliper alignment issues and / or unique resonant frequencies of individual brake rotor / frame / fork setups. It can also be said that the pads themselves are not capable of making noise since they are one single piece, it is always an interaction between two items that creates noise.

- It was clear that some pads performed significantly better from cold / the first brake application. This could be felt through the testing rig, and it matched human experience out on the trail.

- It was easy to detect even a 10% change in braking power from how the test machine ‘felt’, and this matched real-world experience. This is significant in easing arm pump on a long descent, for example, since the rider is having to do a lot less work when a pad generates more braking power for the same finger effort. This is especially pronounced when a pad ‘ramps up’ and gives more friction at a higher temperature (Trickstuff Power, Gorilla Enduro Pro Ultimate), as opposed to ‘fading’ and reducing friction coefficient with increased temperature. It can also be noted that once a pad reaches the limit of its temperature window, it generally starts to increased wear significantly as well as drop power.

- There was a general but loose trend that pads which produced less braking power from cold had more power once fully warm / hot. This makes sense given what we know about brake pad material composition.

- The back plate material or design did not make a noticeable difference to caliper / rotor temperature or braking power. Perhaps this would have been different with a cooling fan running.

- We now feel that the pad bedding in process needed to continue to a higher temperature than 225°C. We saw braking power dropping off around 250°C and then recovering around 350°C for many of the pads. This is an indication of green fade, and significantly affects the validity of the results.

- There was a clear correlation between pads with higher braking power at high temperatures ending their test at a higher rotor temperature. We believe there are a few factors at play here, most notably a higher coefficient of friction provided by the brake pad (ie. higher braking power) ramping up temperatures in the rotor faster without this heat having time to soak into the caliper. Related: it was also noted that the pads with lower power readings tended to need more blocks of brake applications before the caliper temperature reached the point at which the test was stopped. This would make sense. An example: There are 19 rows of data / 19 brake application blocks for the Enduro Pro Ultimate (Orange) pads, but 32 rows of data for the Enduro Pro Resin (Black).

- The rotor type appeared to make as much if not more difference to braking power than the pad type. Braking power was instantly and significantly increased upon fitting the TRP rotor – especially from cold. For this reason, we plan to carry out further testing in the future concerned specifically with rotor design.

Other notes

Fast wear was seen on the Trickstuff and ceramic based Gorilla pads once up to higher temperatures – a visible pile of dust was on the caliper at the end of the test.

The Uberbike Heat Escape pads had a noticeably soft feeling at the lever – this makes sense given the hollow back plate.

It is not covered in the scope of our testing, but a general note is that pads with higher metal content create faster rotor wear. This may be a factor to consider for some riders.

We wondered if many brake pads never see a full and proper bedding in process. It appears that the resins are not cured until at least 350°C in most pads – this is enough to leave them smoking, an indication that the gases are escaping, and discolour the rotor slightly to a brown or purple colour where the friction band meets the arms. I cannot remember the last time I had my brakes hot enough to do this. Gorilla Brakes have a commercially available pad bedding in machine, but my opinion has always been that it simply cannot get brakes hot enough to bed them in properly, so perhaps this is a further test to be carried out.

Limitations

Again, these are in no specific order:

- Despite an extra bedding in process as we were aware they would take longer to bed in, the sintered pads were still not fully bedded in even after the main test! This will have affected the results significantly, so we need to be aware of and plan for this next time.

- We were not able to run the fan due to limitations with the test equipment – how significant is this given that we are trying to replicate real-world conditions as closely as possible?

- The testing only shows data for dry and clean conditions, which are hardly common for mountain biking. Could it be said that this fact reduces the value of our testing?

- Pad wear wasn’t measured, and would be tricky to add into the procedure accurately, but we will try for future testing.

- The power monitor for the lathe appears to display an average reading of the last 3s. This was recognised during testing, and I then began waiting for 4th ‘update’ on the screen. This meant that sometimes brake applications were closer to 3.5 or 4s, and this is likely to have affected rotor vs caliper temp plots since temperatures will have been built more quickly. To get around this, any future testing will have a minimum of 4s brake application blocks, even though this is likely to require longer cooldown periods.

- Switching test protocol half way through each pad test from 3s on / 7s off to 7s on / 3s off left a ‘gap’ in testing and this was very hard to be consistent with. We believe this has affected the rotor vs caliper temperature results to some degree, but has had little effect on the rotor temp vs brake power results.

- There were often lots of data points very close together when rotor temperatures rose, and (we now believe) due to the bedding in process being incomplete this led to some variances in power readings which may not have been due to the pads. For this reason, some of the data has been omitted to smooth out the plots.

Further Testing

For a further round of pad testing, the brake system will be updated to a HINE-R Wilfred caliper, TRP Trail Evo lever, HINE-R hose and TRP R1 rotor. We will then have two identical brake setups available at all times to ensure a seamless transition should one system fail mid-testing. We also believe the 2.3mm solid rotor is a closer match to the demands of current MTB riding, which is where the majority of our interest lies.

A more consistent and accurate test protocol is needed for the ‘switch point’ between low and high temperature testing at 200°C, and this needs to be more closely adhered to. At the moment, the following is being considered, but further lab testing will be needed to confirm this will be suitable:

- From cold, 4s on / 10s off until rotor temperature reaches 200°C.

- Then 6s on / 8s off for two ‘rounds’ as a transition.

- Then 8s on / 6s off until caliper temperature reaches 120°C.

We will also add a third stage to the bedding in process, heating the rotor to 350°C, and increase the temperature of the second stage to 250°C.

On top of the more strenuous bedding in process, we plan to carry out two main tests per pad instead of just one. This should help to further confirm accuracy and consistency of the results.

We plan to check pad wear in future tests by weighing the brake pads when new, after bedding in, and after the full test protocol using a scale with 0.01g resolution.

It is possible that we could add a wet test if we can devise a method of applying a consistent amount of water per brake application. This may involve one ‘pump’ of a spray bottle per brake application, for example, or a consistent ‘drip feed’ of water onto the rotor. We believe that pad compound and rotor design make a significant difference in wet conditions.

We are wondering if, for many riders, getting sufficient heat into the brake system is more of a consideration than dissipating it. This will of course be rider, terrain and weather specific, but with much of current marketing and testing being aimed at maximum fade resistance, little of it appears to concerned with cold performance. The Enduro Pro Ultimate pads were still performing faultlessly even when the hose melted and the rotor was glowing orange, yet this is not a condition we see very often – perhaps a rear brake on Alpine descents in the middle of summer. From personal experience, the first brake application during a wet, muddy ride in the North of England in the depth of winter is a more common condition and perhaps investigating / designing a brake pad and rotor combination for this would be beneficial. For this reason, we have purchased equipment to log real-time brake temperatures for an average rider on wet and muddy UK trails – it will be interesting to see what data comes back!

Back-to-back testing of multiple rotor designs, styles and thicknesses to assess how these affect braking performance has already been planned. Rotors have been sourced, and these tests will be carried out in the very near future.