Glossary
What is Ride Frequency? Formula, Typical Values & Spring Selection
Ride frequency is the natural frequency at which one corner of the car would bounce on its spring if undamped, expressed in hertz (cycles per second). It normalises spring stiffness against the weight it carries, which makes it the best way to compare suspension stiffness across cars. Road cars sit near 1.0–1.5 Hz, non-aero race cars 1.5–2.5 Hz and high-downforce cars 3.0–5.0 Hz or more.
| Car type | Front (Hz) | Rear (Hz) | Reason |
|---|---|---|---|
| Road car | 1.0–1.5 | 1.1–1.7 | Comfort |
| Club / production race car | 1.6–2.2 | 1.8–2.5 | Mechanical grip on bumpy circuits |
| GT3 / touring car | 2.0–2.8 | 2.2–3.0 | Moderate aero plus kerbs |
| Formula / prototype | 3.0–5.0+ | 3.2–5.5+ | Hold ride height under downforce |
Worked example
Suppose a corner carries 280 kg of sprung mass and the wheel rate is 35 N/mm (35,000 N/m). f = (1 / 6.283) × √(35,000 ÷ 280) = 0.159 × 11.18 = 1.78 Hz. To reach 2.2 Hz you would need a wheel rate of about 53 N/mm, so with a 0.75 motion ratio the spring would need to be roughly 95 N/mm (540 lb/in).
Why the rear runs higher
When a car hits a bump the front axle hits it first. If the rear bounces slightly faster, both ends complete their oscillation at about the same time and the car settles flat instead of pitching. A rear frequency 10–20% above the front achieves this at typical speeds.
Frequently asked questions
Should I include the tyre spring rate?
For stiff aero cars, yes. The tyre and suspension springs act in series, so the true ride rate is lower than the wheel rate. For softer cars the difference is small.
What is roll frequency?
The equivalent calculation for the car rotating about its roll axis, using total roll stiffness (springs plus anti-roll bars) and roll inertia. It is used to compare roll stiffness between cars.
Does damping change ride frequency?
Damping slightly lowers the frequency of the damped oscillation and controls how fast it decays, but spring selection is done on the undamped natural frequency.
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