Disc brakes are unquestionably the most powerful brakes you can have on your bike, but for them to be quiet, consistent and powerful, they need some dedicated and careful maintenance and regular cleaning. There are many opinions on how to clean your disc brakes, so we've talked to industry experts to clarify what really is the best way to keep your disc brakes clean and avoid brake contamination.
Whether you have mechanical or hydraulic disc brakes, the issues with disc brakes include all sorts of noise; usually characterised by rubbing and squealing. These are all indicators that you need to clean your disc rotors. The common culprit to these brake noises is simple brake contamination or dirt on the disc rotor surface. Oil or any other substances on the disc rotor or pads will reduce friction between the two surfaces, therefore, affecting performance which is as important if you're riding singletrack trails, downhill mountain biking or gravel racing.
The obvious solution to the problem is to always have clean disc brakes and brake pads, but there's a lot of uncertainty as to what is the best way to clean your disc brakes. First, you don't want anything that might leave a residue, but at the same time, you don't want to harm the braking surfaces and system you're cleaning.
We chatted with industry experts; Shimano, Fibrax, SRAM, Juice Lubes and Hope Technology, to see what they recommend for cleaning brake rotors and pads and if there's anything that can be done to save a contaminated brake pad.
How to clean disc rotors?
When it comes to cleaning bike disc rotors, the general consensus is to use a specialist product that doesn't leave any residue, such as isopropyl alcohol. Hope says: "We recommend either methylated spirits or isopropyl alcohol as these both leave no residue on the rotors. Keep away from white spirit as this will leave an oily film.
"If using brake cleaners make sure you use a bicycle-specific one as car brake cleaners sometimes include oil to stop cast iron discs from rusting."
"Disc brakes work best when there is a consistent braking surface created by material transfer from the pad to the rotors. We have found that cleaning with isopropyl alcohol does a good job of maintaining this relationship while removing grime," James Alberts, SRAM's brakes Product Manager confirms.
"We recommend a mild soap and water to clean disc brakes. This is to help avoid contamination of the pads and rotor. Brake cleaners and other sprays are unnecessary. Do not use compressed sprays to clean brakes as these can cause seal swell. We try and protect sealing surfaces as best we can with our design, but spraying a lubricant at the end of your lever will certainly contaminate your seals making your lever feel sluggish, so stick to soap, water, and isopropyl alcohol," Alberts continues.
Finding the right disc brake cleaner isn't too hard as many brands have a product dedicated to this purpose.
"Our Juice Lubes Brake Juice is a bike-specific cleaner, that is formulated to be low in toxicity - this is what makes it kind of seals and pads which are a lot more delicate than say those of a car where seals are much larger and therefore tougher/more resistant to more aggressive and toxic cleaners. This also helps break juice to prolong pad life by not causing any deterioration to the pads. Our brake cleaner won't corrode or cause oxidization to metal either so your callipers remain looking tip top and shiny," Rob Cook of Juice Lubes explains.
What is disc brake contamination and how to avoid it?
Disc brakes are notorious for getting contaminated, and it really doesn't take much for this to happen. It might be a case of you grabbing the rotor with bare hands, some chain lube spraying onto the disc brake, or tubeless sealant getting onto the braking surfaces. It's really easy to contaminate the disc pads or rotors when you're maintaining or cleaning your bike. But this is not the end of them - all you need to do is to give your disc brakes a good clean.
How and when you clean your bike's disc brakes is important.
"Our advice is that disc rotors should be cleaned after you clean your bike to help avoid contamination. Many people will use a hose to wash dirt and grease off their bikes but the spray can find its way onto your rotors. That's why it's best to leave cleaning the rotors until last. It's important also not to use the brakes during cleaning because the grease from the rotors can make its way onto the pads, Ben Hillsdon from Shimano points out.
"The most common contaminants we see are from chain lube overspray and tire sealants. Be careful to get your chain lube where you want it. Also, removing the rotor from a wheel when replacing tire sealant or installing a new tire can help prevent accidental contamination," SRAM's Alberts confirms.
Ellis Blackman from Fibrax points out another frequent reason for contamination: "With the ever-increasing use of spray lubes, silicone polishes etc. contamination by overspray is a HUGE issue - If anything is sprayed near a bike, it'll contaminate the brakes.
"Don’t use sprays near your bike, if you have to use something, walk several meters away from the bike, spray into a rag and then wipe over [the parts]."
How to fix contaminated disc brake pads?
Once a contaminator gets to your disc brakes, it will contaminate the disc rotor and the brake pad. The disc rotor clean might be as easy as a wipe with some isopropyl alcohol, but cleaning disc brake pads is a more complicated matter.
Bicycle disc brake pads are made of different compounds, the most general ones being sintered or organic, and they absorb the contaminator, whether it's oil, sealant or anything else. If you've had a look at contaminated disc brake pads, you might have noticed they have a shiny layer to them. That layer doesn't grip the rotor very effectively, meaning that your braking power is compromised.
There are many ways to clean contaminated brake pads, but you should be cautious when trying some of the home remedies. Some suggest giving them a good rub with sandpaper to remove the top layer, some say you should stick them in the oven or bake them with a blowtorch to burn off the contaminants. None of our experts suggested this and suggested that the only way to remedy a contaminated disc brake pad is to replace it.
"To maintain consistent performance we recommend replacing disc brake pads should they become contaminated," SRAM's Alberts comments.
That's a stance backed up by pad manufacturer Fibrax, who says contaminated brake pads are fit only for the bin.
Hope was the only one suggesting there might be a way to salvage those contaminated brake pads: "If the pads have surface contamination you can sometimes resurrect them by rubbing the surface on sandpaper. Just make sure you put the pads back on the same side as they may be worn at an angle."
In summary - to keep your disc brakes clean
- Avoid contamination in the first place by not using sprays near your bike and/or removing your wheels while you wash or lube the bike
- Clean your brake system with normal soap and water
- Avoid white spirit and instead use isopropyl alcohol, meths or another solvent that doesn't leave a residue to clean your rotors
- Never touch any of the braking surfaces with bare hands
- If you want to use a brake cleaning spray, buy a bike-specific one and try to avoid spraying it on the lever and calliper seals
- Contaminated pads should generally be replaced, but you might be able to save light surface issues with a spot of sandpaper
With thanks to Fibrax, Hope Technology, Juice Lubes, Shimano and SRAM.
You might also like:
- SRAM mountain bike disc brakes explained - Level T, TLM, Ultimate, Guide R, RS and RSC, plus G2 and Code models
- Shimano mountain bike disc brakes - Deore, SLX, XT, XTR, Saint, Zee models and more