Discs

On Wednesday, November 15, 2017 at 11:47:23 PM UTC-7, Tosspot wrote:
Why do they have holes in them?

Car discs don't, motorbike discs don't, aircraft discs don't. Why do
bicycle discs have them?

drill holes collect material melt for new ...cost effective

balance

heat dissipation more holes more surface area.

the manufacturer takes a thermal picture of his hot rotor then drills there n another hole over there to balance. Ceramic disc may avoid thermal hot spotting or boundaries

Harris Allen has info with an interesting NE obs on road bikes

https://www.sheldonbrown.com/disc-brakes.html