〰️ Suspension Spring Rate

Written and maintained by the PhDino author · Last reviewed 21 September 2026 · Checked against 2 independent reference calculations · how PhDino checks its numbers

The difference between a spring's own stiffness and the stiffness it actually delivers at the wheel, and the ride frequency that results.

A suspension spring's rate — how much force it takes to compress it a given distance — isn't the same as the stiffness actually felt at the tire's contact patch. Most suspension designs don't compress the spring by the same amount the wheel itself moves; a lever-like linkage (control arms, rockers) usually moves the wheel more than it moves the spring, which is captured by the motion ratio. Squaring that ratio when converting to wheel rate reflects that the mechanical leverage affects both the force and the distance in the relationship.

Ride frequency — how many times per second the car naturally bounces on its suspension if disturbed — is a genuinely useful single number that combines wheel rate with the actual weight it's supporting. Race cars deliberately run much higher ride frequencies (stiffer suspension relative to weight) than road cars, trading a harsher ride for less body movement and more consistent tire contact under hard cornering, braking, and acceleration.

Key formula

Wheel rate = spring rate × motion ratio²
Ride frequency (Hz) = (1 ÷ 2π) × √(wheel rate ÷ mass)

Notes & limitations

• Typical ride frequencies run roughly 1–1.5 Hz for a comfortable road car, up toward 2–5+ Hz for a stiffly sprung race car — there's no single "correct" number, since the right frequency depends on the specific track, tire, and aerodynamic package a car is set up for.
• This calculates one corner's ride frequency in isolation — front and rear ride frequencies are usually tuned to a deliberate ratio relative to each other (commonly slightly higher at the rear) to control the car's pitch behavior, not just set independently to the same number.