Eli5: Why do bicycle disk breaks have “%” and “V”s stamped through them. Is this the most efficient way of displacing heat / reducing cost ( materials ) or does it just look cool?

Question

Eli5: Why do bicycle disk breaks have “%” and “V”s stamped through them. Is this the most efficient way of displacing heat / reducing cost ( materials ) or does it just look cool?

In: Engineering

Answer 1

Those disc brakes are likely going on mountain bikes. Dirt, mud and water are likely to get on the brake rotor surface. The cross drilling and slots serve 2 purposes:

1. Allow the debris to get wiped off as the rotor rotates
2. Allow the hot gasses that build up from heavy braking to escape