RIDEFAST AUG 21

When the rotor is subjected to serious heat, it expands. By allowing it to float
separately from the mounting face it is free to expand and shrink again at will
without being constrained by its mounting. When this expansion takes place is
does so in all directions at once and it will not be constrained.
If you prevent this from happening in one direction (by fixing it on its mounting
face) it has no choice but to warp, so floating discs and semi-floating discs are
made in two parts to allow the discs to expand and prevent them from warping.
These are a high performance type brake disc.
Bikes of more moderate performance can use fixed brake discs perfectly
happily and you will also see that most rear brake discs are fixed. This is because
they don’t get used as hard and therefore subjected to as much heat.
Even so, most rear brake discs are thicker than the front brake discs and
this is a compromise because the cooling is not as good as the front discs.
They don’t get as hot but don’t cool as well either, so the thicker material
helps prevent them from warping.
Ventilated brake discs:
Possibly the most common type of disc, (more on cars than bikes), a
cast design that sees the two ‘faces’ of the disc spaced apart, giving
room for cooling channels which allow heat to escape, preventing the
disc from getting too hot and cracking, while also increasing the life
of the pads. Initially they featuring straight channels but they have
evolved through the years to improve airflow.
Drilled Brake discs:
Under heavy braking or in race conditions gases and particles are released
forming a layer that prevents the pad from touching the disc
effectively. Holes drilled through the disc give the gases and particles
an escape route with a positive spin off of reducing weight
of the part. However, if not done correctly, this process can
also compromise the structural integrity of the disc. The
brake disc acts as a big heat sync and by drilling it full
of holes means there’s less of it to dissipate the heat
generated by the friction of braking. However, with
the evolution of braking technology and materials
modern brake pads use are not as gassy as
their predecessors thus reducing the need
for drilling and the discs are manufactured
more than strong enough. Fracturing is an
exceptionally rare occurrence.
Slotted or Grooved brake discs:
The slotted, or grooved design is
another attempt to answer the
same issue. Slots or grooves in the
surface of the disc allow gases to
escape with the additional benefit
of the scraping action introduced
by the slots assist with cleaning
the pad as well as the edges of
the grooves increasing friction,
(albeit at the expense of increased
pad wear), and stopping
power. And just like drilled discs,
they look pretty awesome.
Wave brake discs:
Wave discs have been around in
the motorcycle world for years.
Wave discs place the mass closer
to the axle for reduced inertia,
better heat dissipation and lower
weight. They were originally developed
for Motocross bikes; however
they see use on road going motorcycles
too.