BACK-TO-BASICS

FRICTION IS YOUR FRIEND

BRAKE PAD AND ROTOR CLEANING TIPS & TRICKS

Tech Tuesday Presented by TRP

Wondering why your mountain bike’s brakes aren’t feeling as good as they used to? Looking for the best solution to cure contamination or fade? Or are you just looking to make your brakes work powerfully and reliably as they can for as long as they can? We sat down with TRP, World Cup racer Neko Mulally and TRP’s lead engineer Colin Esquibel to give you some tips on cleaning and maintaining mountain bike disc brakes. If you don’t like to read, just check out our in-depth YouTube video and please be sure to subscribe as we’re really trying to grow our channel! Enjoy.

Brake Rotors
Brake rotors are available in a range of diameters, from weight-weenie approved 140mm discs to monstrous 223mm units that are appropriate for stopping a tank. A larger rotor will add weight overall, but at The Loam Wolf we’d always err on the side of bigger is better. The increased control and confidence in your brakes at the end of a long descent pays dividends. It’s important to make sure your bike will accept a larger rotor and you won’t void any warranties, but it’s one of the simplest upgrades you can make to your stoppers.

Rotor thickness is something that’s often overlooked, but it can make a big difference. Standard rotors are 1.8mm-2mm thick, whereas TRP brakes use a thicker 2.3mm rotor. This not only lets the rotors handle and dissipate the heat a little better, but makes them much less prone to warping or bending. Again, we like to opt for thicker rotors where possible, but it’s important to ensure your brake caliper will accept some of the thicker units.

Brake Pad Material
Depending on the brand, there are usually two or three options for brake pad materials. The standard options are Metallic (Sintered), Semi-metallic (Hybrid material) or Organic (Resin). The resin pads will deliver a softer, more delicate lever feel upon initial pad contact to the rotor, making them the choice for World Cup downhill superstar Neko Mullaly. Once up to temperature, the initial bite is awesome on resin pads, however they can be more susceptible to heat fade, don’t work as well in wet, and don’t last as long as the alternatives.

Metallic pads solve some of the issues from the resin option, however they are louder, slightly more “harsh” in their initial pad contact with less ramp up, and have less initial bite when hot. They resist heat fade a lot better and last a lot longer though, especially in wet, gritty, or sandy conditions. The folks at TRP, and our own personal experience suggest that if you’re a heavier rider or someone who’s on the brakes a lot, metallic pads are the way to go.

Semi-metallics strike a middle ground between the two, not quite reaching the bite levels of a Resin pad nor the longevity of the Metallic. What they do however is blend some of the bite, and lever-feel traits with longevity and heat management. Not quite the best of both worlds, but a good all-rounder.

Cleaning Brakes
When it comes to braking, friction is your friend! It’s essential to be very cautious when handling, washing and lubing your bike and to ensure any products that find their way onto the braking system don’t contain any lubricating ingredients like silicon.

Colin Esquibel at TRP won’t even touch a brake rotor with his bare hands, you really don’t want to risk the residue of your Cheetos or natural oil finding its way onto your brakes. TRP and TLW recommend only using Isopropyl alchohol or IPA for brake cleaning as it leaves behind no residue and is safe on o-rings and seals. A spray bottle is particularly useful here to help get it into hidden areas. Isopropyl is probably the cheapest and best hack to keeping your brakes running stronger longer! Use it!

Another thing to consider is your driving situation when transporting your bikes. If you’re carrying your bikes outside your car or truck, driving in the wet, through snow and de-icer, or dried dust, all this crud will cause issues. The debris will fly up onto your rotors and pads, and when you start your first downhill the contaminants will bake into the pads and rotor and ultimately lower friction and overall brake performance. Consider adding a cover to the brakes to keep them safe. Something like Muc-Off’s rotor protectors are a great option, but if you’re budget minded, Neko says he used to use Shower Caps from the .99 Cent store. Also a great reason to carry a spray bottle of Iso. Get to the trail, pull our your sprayer and a rag, and clean all that road gunk off your brakes.

If you’re starting to feel a lack of bite in the pads or they’re making noise, it’s worth popping the pads out and refreshing the braking surface. This is as simple as sanding off the top surface of the pads, which may be glazed or dirty, to reveal the fresh pad surfaced below. Colin at TRP recommends drywall sandpaper for brake pad sanding, as it has holes that let old pad material fall through, preventing it from being rubbed back into the pads. Rubbing the pads face-down onto a piece of sandpaper using a figure of 8 movement, you can quickly reset the pad surface – just keep on sanding on a flat surface until you get a uniform brake surface without the shine of a used pad. If there is oil on your pads or disc, you’ve got to throw away the pads as the oil will seep into the pores and it’ll leach out no matter the cleaning you do. You may clean them and find they feel good initially, but after a few hard braking efforts this oil will find its way onto the braking surfaces again, so be safe and chuck them.

Resurfacing brake rotor is a similar process to the pads but can be done with the rotors still mounted to the bike. It’s always a good idea to check your caliper and rotor bolts are torqued adequately, as a loose brake can spell disaster, or annoying vibrating harmonics. You’ll want to start by wiping them off with some Isopropyl alcohol on a rag. Then take some steel wool with some IPA, and go around the rotor rubbing away any baked in dirt and debris, until you’re left with a renewed, cleaned braking surface. Give the rotor a final wipe with a rag and IPA to make sure it’s as clean as possible, and you should be good to go. At the World Cups, Colin will go so far as to blowtorch the rotor to burn off any remaining steel wool, rag etc. Overkill perhaps for the average joe, but a sure-fire way to ensure the rotor is as clean as possible for his team riders.

IMPORTANT STEP – Once the pads and rotors are resurfaced and cleaned, it’s time to bed in the rotors and pads again before hitting the trails, give this a watch for bed-in tips. After a few minutes getting the rotor surfaces primed for some hard braking, you can enjoy your stoppers that should now be feeling damn good.

TRP kindly provided us with their essential DO’s and DON’Ts list, which even taught us veterans a thing or two, and will hopefully keep us from ever re-living the PTSD-inducing times running old Hayes and Avid brakes back in the day.

DO’S:

Use Isopropyl alcohol and a clean towel for anything and everything. It is your best friend.
Torque all bolts and screws to manufacture guidelines
Bed your brakes in every time you change pads, rotors or reset the pad surface by sanding them down.
Clean your rotors with Iso after extremely muddy or dusty rides.
Clean your rotors after driving long distances if you use a hitch rack
Clean your rotors after driving down a dusty dirt road
Clean your rotors after washing your bike
Clean your rotors before installing new pads.

DON’TS:

No touching of the rotor track or pad surface with fingers, tools, or dirty surfaces.
Do not use lubricants such as WD-40 on the rotors, pads, or calipers. Ever. Even if you think you should. Don’t do it. Yes, we actually get lots of messages from people trying this.
Do not use grease to lubricate pistons, only use mineral oil.
Do not use soap or any other degreasing agents to wash the rotors or calipers
Do not use automotive or name brand disc brake cleaners. Only use isopropyl alcohol.
Do not use aerosol lubricants (tri-flow among others) or sunscreen near rotors or pads
Do not use excessive amounts of chain lube without wiping it off with a rag
Do not leave new pads sitting out in the open. Always keep them in an enclosed package or bag or it could lead to contamination.
Do not swap pads from one side of the rotor to the other, or from the front brake to the rear brake. This will cause glazing and heavy vibrations. You must sand the pads and bed them in again if you want to do this.
Do not change pad compounds on the same rotors. Different compounds will create different footprints on the rotor track and mixing compounds will result in glazing and heavy vibration.
Avoid locking your brakes out during the bedding process. It will lead to possible pad glazing and heavy vibration.

MOST COMMON ISSUES CUSTOMERS FACE AND BIKE SHOPS SEE:

Glazed pads: from not bedding them in, from locking their brakes up during bedding, or from swapping compounds on a used rotor.
Contaminated pads: Mostly from customers using WD-40 to try and get any sounds to go away but also very common to see people being less-than-precise with how they apply chain lube other lubricants.
Contaminated rotors: This will lead to contaminating a new set of pads, so always clean the rotors thoroughly before installing a new set of pads.
Loose rotor bolts causing shuddering while braking. Check torque specs every once in a while.
Loose caliper mounting bolts causing shuddering while braking. Check torque specs every once in a while.
Loose compression fittings around the lever and hose connection. This can lead to contamination as the oil runs down the hose to the caliper. Check torque specs every once in a while.

TLW: WHAT GRIT AND HOW DO YOU KNOW YOU”VE SANDED ENOUGH? SAME FOR PAD REFRESH/CONTAMINATION TREATMENT?
TRP: We like to use medium grit sand paper or drywall sand paper. When sanding the pads, we do it in a circular figure-8 motion about a dozen times. You should see the pad material begin to draw out that figure-8. Once you have done a dozen or so you can flip the pad over and look at the material and if you still see some old surface (old surface will be darker compared to freshly sanded surface) then keep until you see a consistent color across the pad surface to ensure the surface is perfectly planed.

This is only for a pad refresh to get rid of glazing or any vibration/noises during braking. If your pads are contaminated, throw them away and get new ones because no amount of sanding can remove the contamination as it will soak into the pores of the pad material like a sponge and be present at every point within the pad life from that point forward.

TLW: WHY SHOULDN’T WE USE AUTOMOTIVE OR BIKE-SPECIFIC BRAKE CLEANER?
TRP: While some aftermarket cleaners are safe to use, some (specifically automotive) can leave a thin film of chemical residue on the rotors because they are commonly made with a combination of different chemicals. This film on the rotors can then be transferred to the pads and change the friction profile between the surfaces introducing possible glazing, vibrations, and noise. Because isopropyl alcohol is an isomer of propyl alcohol, it is an extremely effective solvent against all unsaturated oils (mineral oil) and lipo-proteins allowing it to dissolve and remove pretty much any all organic and inorganic contaminants that might be present on a rotor and because it is a pure (sometimes diluted with water ie 70% isopropyl alcohol like you would find on the shelves of CVS) and colorless chemical with a very low boiling point, it has the ability to completely evaporate off the surface of the rotor in room temperatures leaving it crystal clean and free of harmful contaminants. This is the main reason why we say use only Isopropyl, because it is the only way to assure that the system is completely clean.

TLW: WHAT ABOUT SCORCHED ROTORS, WHEN THEY GET DISCOLORED/BLACK? DOES THAT CAUSE ANY ISSUES?
TRP: A scorched rotor can sometimes lead to issues of warping or a decrease in surface friction depending on how scorched it is and where it is scorched. If the track of the rotor (where the pads contact) is discolored with brown/purple/blue coloring it indicates that the rotor surface has reached a temperature range of about 700-1000 degrees Fahrenheit. At this temperature, the rapid cooling and reheating of the metal can induce structural changes to the track causing it to warp leaving you with imperfect pad contact (less stopping power and screeching sounds) or glazed pads (superheats the material and melts the surface). This is one of the main reasons why we started using thicker 2.3 mm rotors back in 2017 because they provide 47% more lateral rigidity so even at these temperatures and beyond they prevent warping issues ensuring the brakes are trouble free and safer to use on E-Bikes and heavier DH/Enduro. If you see this discoloring on the spiders (below the rotor track bolting to the wheel) it just indicates that the material below the track was heated but most of the time it won’t produce any issues. Just bragging rights at that point!

If you see the color black – like sharpie black – your rotors are likely contaminated as the black coloring is not a natural temperature indicator of stainless steel, it is just burnt contaminants. Clean those rotors super good with Iso and if the black coloring stays, replace the rotors as you’ll just contaminate new pads if you leave it on.

TLW: WHAT ABOUT BOILING FLUID ETC? HOW DO YOU KNOW IT’S BOILED? DOES THAT MATTER? INCREASE BLEED FREQUENCY? SAY AFTER A TRIP TO WHISTLER WHERE YOU RODE 100,000 FEET OVER 6 DAYS.
TRP: Boiling fluid is certainly possible if you are dragging the rear brake for an extended downhill, but it is actually super rare with our brakes because we use mineral oil with a BP of 270 deg. C (~500 deg. F) and house more of it in the caliper making it a larger heat sink and much harder to reach that boiling point. We also use a thicker rotor and hybrid composite pistons making it much harder for heat to reach the caliper. However, you will know if it’s boiled when you start being able to pull the lever past your normal bite point and to the bar more and more on the way down the hill and when stopped. Often referred to as “heat fade”, the oil will begin to boil in the caliper, releasing gas (air) which is compressible compared to mineral oil leaving you with a very spongey and unresponsive feel (no bite point and no power) and some white knuckles as you squeeze the levers for dear life trying to stop. If you do experience heat fade and your bite point is different/non-existent, then it is a great idea to do a full bleed of your brakes to remove that air and any of that boiled oil (after boiling the composition will be altered rendering it less compressible than before) so your brakes are once again working properly and safely.

If you just get off a 100K descent whistler trip, it all depends on how your brakes “feel” afterwards because a 250 lb. rider on a XXL frame will introduce much more heat into the system than your flyweight buddy. In any case, it is never a bad idea to bleed your brakes or increase your service intervals If you are riding consistently steep descents like that, but it really does all go off lever feel and if it is solid or squishy.

School is out for summer folks. We hope you enjoyed the tech heavy 411 feature and that we’ve saved you some potential grief or even resolved some problems you’ve been having with your brakes. Keep your braking surfaces clean, ensure everything’s tight and straight and don’t forget the Isopropyl Alcohol.

To check out TRP’s awesome products head over to TRPcycling.com