How to Maintain Bicycle Disc Brakes

Written by : Mr Mamil
Last updated :

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Disc Brakes on Road Bikes

There’s a strong chance that all new bikes today come equipped with disc brakes. Disc brakes provide excellent and reliable stopping power in all weather. This is a massive leap forward from worrying about increased rim braking distances with alloy and carbon wheelsets in inclement conditions.

But how accustomed are they to basic disc brake maintenance and care?

  • When do the disc rotors and pads need to be changed?
  • Do I need to clean them regularly?

Here are eight basic disc brake maintenance do’s and don’ts to help you get the most out of your mechanical or hydraulic disc brake system.

Clean the rotors after a wet ride

The crud and grime would accumulate on the disc rotors and brake pads on wet rides. Every time you engage the brake, the crud and grime layer thickens, and eventually, the braking effectiveness and power will be compromised.

The grime that isn’t cleaned after a wet ride reduces rotor and pad life and the system’s efficiency.

There are many disc brake cleaners on the market today. An alternative is a DIY home method with clean towels and isopropyl alcohol. Apply your product to a clean cloth and wipe the disc in one direction only, don’t double back. Fold the material after each go so it’s grease and dirt free for the next pass.

More reading : How to Clean Disc Brake Pads and Rotors

Regularly check for rotor wear

Disc rotors are made of metal, sturdy stuff, but they have a life. It’s important to check their wear periodically, and it can be done without removing the disc from the wheel.

The new disc rotor thickness varies by brand and is approximately 1.8mm. Discs can normally be used down to 1.5mm. The minimum thickness is printed (Min.Th=1.5) on the rotor, or check the manufacturer’s website to verify.

The most reliable method to check rotor wear is a digital vernier caliper. The starting point is 1.8mm (new), so make your measurement and compare. You can also use rotor wear indicator tools such as Birzman and Lifeline.

Other signs of rotor wear can include;

  • Significant decrease in braking power
  • Brakes levers that almost touch your handlebar
  • Rotors that have a glossy hue.

That mirror-like finish on the rotors doesn’t mean you must change them if they’re within approved tolerances. That shine is caused by brake pad material transferred onto the rotors over time.

Give them a second life by removing that glaze with fine sandpaper (cut into small squares to keep the rest of the sheet clean).

More reading : How Long Can Disc Brake Pads and Rotors Last?

Check for warped rotors

If the disc rotors are warped, you’ll probably hear it when you’re riding. Sometimes, rotors can be warped, even if you detect nothing.

The disc rotors warp when they overheat from braking, get damaged in a crash, during travel, if the bike was resting on the rotor directly, or if something was placed on top of it (in your car?).

Here’s how to check for warped rotors,

  1. Remove the wheel
  2. Hold it by its axles
  3. Give it a good spin, so it turns in front of you.
  4. Watch the rotor.
  5. Does it have a wobble or turn true? If it’s extremely bent, it’s best to invest in a new one.

If you have the patience, try using a rotor truing tool that fits over the disc and can bend it back into shape.

Bed in new brake pads

Disc brake pads come in two materials, metal and resin.

Even though they don’t last quite as long and cost a bit more, the resin is preferred for its improved braking sensation and the fact that they aren’t as susceptible to squealing.

Whether you ride metal or resin, you need to bed-in fresh pads before you put them to full use. If installing new disc rotors, change the brake pads so they wear together.

Bedding the pads adapts them to the surface of your rotors.

Here’s how to bed in the new brake pads.

  • Pedal up to a good speed
  • Slowlyengage the brake, not all at once and not 100% (not to a dead stop).
  • Repeat this action at least 15 times per brake.
More reading : How to Bed in New Disc Brake Pads

Don’t pull the brake levers without the wheels on

When you brake, the hydraulic fluid activates the pistons on either side of the rotors to come together, grasping the disc and bringing you to a stop.

The brake pistons are self-centering, so if you pull the levers without the rotor, they have no limit guide and might pop out. They won’t return in place either, and you’ll have to retract them before reinstalling your wheel.

You can prevent this by using a disc brake bleed spacer in place of the rotor when the wheel is out. This is useful, especially if you’re leaving the bike without the wheels on for some time, such as during air travel.

Make sure the disc brake bleed spacer is clean, or you’ll contaminate your brake pads (if you haven’t removed them). These are sold separately, or you can make your own if you have a 3D printer. They’re essential when traveling with your bike (in a case) and useful when riding your home trainer.

Don’t spray water on hot rotors

Heat is built up on the rotor during braking. The heavier the rider, the larger the disc, and the more they are in use (long and steep descents), the hotter they get.

If your rotors are scorching after a long ride or a bombing downhill run, wait until they cool down before washing.

Cold water on hot rotors causes an immediate and drastic change in temperature that can cause your rotors to warp.

Don’t drag the brakes on long descends

Even in normal riding conditions, rotor heat buildup is a natural effect of disc brakes. Throw in long descents, especially steep ones, and we use our brakes even more, which can lead to overheating.

When the disc rotors are hot, they can become glazed with brake pad material which in turn reduces their stopping power. Larger and heavier riders should be even more attentive to this heat build-up since it will take even more force to bring them to a stop.

Dragging the brakes on a long or steep downhill causes overheating, which can lead to eventual brake failure. The wind plays a part in cooling your brakes, but if you’re going safe and slow, there’s not enough airflow for the job.

Pulse your brakes instead of constantly dragging them or alternate between the front and rear.

Reducing your speed is another strategy. Put technology to work for you by purchasing and installing disc rotors designed to dissipate heat better.