Brake bias
Brake bias is how the total braking force is split between the front and rear axles, usually expressed as a front percentage.
Also called: brake balance, brake proportioning
When you brake, weight transfers forward. The front tires are pressed harder into the road and can do more work, while the rears get lighter. That is why almost every car is set up with more braking at the front, often somewhere around 60 to 75 percent depending on the car's weight distribution and grip.
Get the bias right and both axles approach their limits at the same moment, so the car stops in the shortest distance and stays straight. Too much front bias and the fronts lock early, the steering goes light and the car runs wide. Too much rear bias and the rears lock first, which can swing the back of the car around, especially when you are still turning in.
Road cars manage bias with fixed proportioning plus ABS and electronic brake-force distribution. Race cars often have an adjustable balance bar. Changing pads, tires or ride height also changes effective bias, so if the car suddenly feels nervous on the brakes after a parts swap, bias is a prime suspect.
Correct bias lets you use every tire's grip under braking, shortening stopping distances and keeping the rear stable on corner entry.
Rears lock first: the car wants to swap ends. Move bias forward.
At 0.90 g, load transfer puts about 72% of this car's weight on the front axle, so the ideal front bias is about 72%. Too much rear bias locks the rears first, which is unstable. Simplified, 1400 kg demo car.