What is brake bias?

Brake bias is the percentage of total braking force applied to the front wheels. A car with 70% front bias sends 70% of its braking force to the front and 30% to the rear. Most street and track cars target 60–75% front bias depending on weight distribution and tire grip.

How is it calculated?

Brake torque at each axle depends on three things:

• Piston area: total area of all caliper pistons (determines clamping force for a given line pressure)
• Effective radius: the radial distance from rotor center to where the pad applies force, weighted across the pad’s contact area
• Number of wheels: 2 front, 2 rear (equal line pressure assumed)

bias_front = T_front / (T_front + T_rear)

• T: braking torque = piston area × effective radius

Pad outlines & effective radius

A good estimate for effective radius is taking the pad height at the centerline and choosing the midpoint. This calculator goes beyond that and uses the pad shape to calculate the true effective radius. Using digitized Hawk pad outlines, the effective radius is computed by numerically integrating the moment arm across the actual contact area (7-point Gaussian quadrature over fan-triangulated polygons).

r_eff = (1/A) ∫∫ r dA

• r_eff: effective radius - the single radius that produces equivalent braking torque
• A: total pad contact area
• r: radial distance from rotor center to a point on the pad

What the visualization shows

The diagram draws each brake to scale: rotor diameter, pad shape and position, piston diameters and locations, and a 275/40R17 tire outline for wheel clearance reference. The dashed circle shows where an 18" wheel’s inner rim would sit.