Originally Posted by
spelger
So what exactly is brake fade?
"Brake fade" generally means a reduction in braking performance, which can be different things.
Friction fade: If a brake pad gets hotter than its rated max. temperature, the pad can begin to break down, and the friction between the pad and the braking surface will decrease. The cyclist will need to squeeze the brake lever harder to achieve the same stopping force.
Fluid fade: With hydraulic brakes, brake fluid may get hot enough to boil, making the brake feel "spongy" as you squeeze the brake lever. The gas in the piston is the equivalent of a spring that has to be compressed, so the brake lever needs to moved farther to achieve the same stopping force.