The right way to check the thickness of your brake pads
Whichever type of bike you ride, what kind of engine it has (or even whether it's electric),
and how harsh or delicate you are behind the handlebar, the brake pads will eventually wear
out. Most automotive parts are built to endure, but brake pads are designed to wear
gradually with usage, preventing much more expensive parts from needing to be replaced.
Everyone who rides should be concerned about brake wear since, while it will not result in a
catastrophic failure, it will increase stopping times.
You should change your brake pads before the metal baking plate comes into contact with
the brake rotor, since this can quickly wear grooves in it. As a result, it is critical to check the
thickness of your brake pads at least once a year.
While they are little, brake pads perform an important function! Inside the brake callipers,
hydraulically activated pistons form the braking system. The pistons press the brake pads
against the brake discs, converting kinetic energy (motion) into thermal energy (heat), which
is why brakes become hot when in operation.
The friction material's composition determines how strongly the pads grip or bite and how
fast they wear. Various pad formulations may last longer but not bite as hard or prevent
heat-induced brake fade.
When the pads wear down, they must be replaced before the steel backing makes contact
with the disc. Your brake pads require a visual inspection in most cases. Certain
manufacturers may stipulate a minimum pad material thickness. Most of the time, this is
between 2.0 and 1.5mm.
The discs are fixed to the wheels and the brake calipers, in which your pads live, ‘clamp’
down onto the discs when you use the brakes. Think of it like a dog chomping down on a
spinning Frisbee, without all the slobber.
So how do I measure it?
The open face of each caliper is positioned over the edge of the brake disc. Get down at
wheel level and shine your torch into that area – it might take a moment to get the angle just
right. You should see one pad at either side of the disc, right up against it. Unless your
calipers are unbearably filthy, you’ll be able to see that there are two distinct layers to the
pads – the layer closest to the disc is the friction material and the layer behind that is the
metal backing plate that the friction material is bonded to. The cylinders you see behind the
backing plates are your brake pistons.
As a rule of thumb, the layer of friction material should be thicker than the metal backing
plate. If it is a little thinner, don’t panic – simply continue to check your brake pads every
week. You’ll start to get an idea of how quickly or slowly they are wearing, and whether
they’ll make it to your next scheduled service before needing to be replaced.
If the friction material is very thin, just a millimetre or two, don’t take chances. You should
have new pads fitted
The wear indications may be seen without removing the calliper pads, however a better way
is to remove and inspect them. The auditory approach is by far the worst way to evaluate the
pads, as it essentially equals to not inspecting them at all.
Other Indications That Pads Are Worn
Brake and lever pedal Sensitivity
When riding, you may find that you need to press the brake pedal harder to achieve the
same amount of braking. That’s an obvious indicator that the brake pads are on their way
out. Stepping on the brakes moves the pads very little, but multiplies the power you apply to
the pedal, resulting in hundreds of pounds of clamping. The hydraulic system is designed to
automatically adapt for friction material wear, however it isn’t flawless.
If your brakes are severely worn, the system may require the whole amount of brake fluid in
the master cylinder to compensate. If you run the master cylinder reservoir dry, you’ll get air
in the brake lines and a really mushy pedal feel.
Noises
If you have to stop hard, a deep whooshing or moaning sound indicates that your brake pads
are going low. Most current brake pads include small metal tabs that make contact with the
disc when the pad is 3/2nds or 3/4ths worn, resulting in a high-pitched screech. When you
step on the brakes, the wear indicator scream will temporarily disappear.
Rubbing the tabs on the disc will not harm anything, but if you leave it too long, you may
wind up with no friction material. If the metal backing plates grind on the discs, it not only
makes stopping less efficient, but it also destroys the discs.
Mileage
There is no hard and fast rule for how long a set of pads should endure, but you may use
common sense. Pads typically last between 5,000 and 15,000 kilometres. If you are touring
most of the time with heavy luggage you’re looking at a lower figure. But also, seriously
consider your riding. Are you an early bird? Are you hitting the brakes too late? Do you come
to a gentle halt or do you slam on the brakes? All of this might shorten the life of the pads.
What Are Brake Pads Made Of 101?
There are lots of different types of friction material but the main types are are:
Non-metallic/Organic – a combination of substances bonded together, originally they were
mostly asbestos. Short service life, but quiet and reduced brake disc wear. These are the
most common pads fitted to bikes.
Semi-metallic – Synthetic substances, plus metal compounds. Harder wearing than non-
metallic, but harder on brake discs, and can give poor pedal feel until warm/hot.
Fully-metallic – Generally reserved for race and street applications. Can withstand high
temperatures, but need to be hot to work effectively and are very hard on discs.
Ceramic-metallic – Composed of a dense ceramic material and copper strands. The most
expensive of all the pad materials, consistent performance whatever the temperature,
extremely quiet operation.
Pad material is chosen to perform within an optimal temperature range, thus you’ll need to
assess what you’re using your bike for, track, street or just commuting.
Like tyre checks, chain and sprocket maintenance, checking your brake pads is one more
simple task that can help you stay safe and in touch with your bike’s mechanical ‘health’. Get
into a routine and you’ll find there’s real peace of mind in knowing for sure the state of your
bike’s vital systems before you head out for a ride.
