How ideal brake bias works
Braking throws weight forward. The amount that transfers to the front axle depends on how hard you brake, how tall the centre of gravity is and how long the wheelbase is:
front load % = static front % + (CG height ÷ wheelbase) × g × 100
Each tyre can only brake in proportion to the load on it, so the ideal brake bias matches the dynamic load split at your target deceleration. Bias the fronts too little and the rears lock first — the scary one, because it spins the car. Bias them too much and you leave rear grip unused and overwork the fronts.
A tall, short car transfers more weight, so it needs more front bias. A low, long car transfers less. This calculation gives the theoretical ideal; real cars add a margin toward the front for safety, and a bias valve or different pad compounds fine-tune it.
FAQ
Why bias the front more?
Because weight shifts forward when you brake, loading the front tyres and unloading the rears. The front brakes must do more work to use that extra grip; if the rears do too much they lock and the car becomes unstable.
What's a typical brake bias?
Road and track cars commonly run around 60–70% front, but it depends entirely on weight distribution, CG and grip. Use the number here as a target and adjust for how the car actually behaves at the limit.
How do I change brake bias?
Via front/rear caliper piston area, rotor size, master-cylinder sizing, a proportioning or balance-bar adjustment, and pad friction levels. Small changes matter, so adjust and test in a safe environment.