How wheel rate and ride frequency work
The suspension linkage means the spring moves less than the wheel, and rate scales with the square of that ratio:
wheel rate = spring rate × motion ratio² · f = (1 / 2π) × √(wheel rate ÷ sprung mass)
Because of the square, a motion ratio of 0.7 means the wheel only feels about half the spring's rate — which is why installed spring rates look so high. Ride frequency normalises rate against the weight it carries, so you can compare cars of different mass and balance the front-to-rear feel.
What ride frequency should I target?
Rough guide (sprung natural frequency): 1.0–1.5 Hz comfortable street, 1.5–2.0 Hz sport / fast road, 2.0–2.5 Hz track, and 2.5 Hz+ race with aero. Many setups run the rear ~5–10% higher than the front so the car settles flat over bumps.
FAQ
Where do I find my motion ratio?
It's the wheel travel divided by spring travel for that corner, often between 0.6 and 1.0. Strut cars are near 1.0; many wishbone rear ends are lower. If you don't know it, 1.0 gives you the spring rate as the wheel rate (a slight overestimate).
Sprung or total corner weight?
Use sprung mass — the corner weight minus the unsprung parts (wheel, tyre, brake, roughly half the arm/spring). As a rough cut, subtract ~40–50 kg per corner from the scaled weight.