Ride frequency

Ride frequency is a measure of an axle's tendency to bounce. It essentially is a measure of stiffness of the axle as it is proportional to the square root of the spring rate. An axle with a greater ride frequency will bounce of bumps more rapidly. Race cars often have a ride frequency between 2 to 5hz.

A stiffer suspension setup increases ride frequency. The ride frequency of the rear axle is often higher than the front to reduce pitching. Otherwise, the pitching occurs because a bump is hit by the front wheels first and then the rear wheels. Thus, the rear ride frequency must be greater to "catch up" to the movement of the front suspension in order to reduce pitching of the car as the suspension settles.

ride height over time when the front axle has a greater ride frequency than the front axle. This graph does not incorporate the eventual settling of the suspension.

ride height over time when the rear axle has a greater ride frequency than the front axle. This graph does not incorporate the eventual settling of the suspension.

To Calculate

To calculate an induvial corner's ride frequency use:

$f=\frac{1}{2\pi }\times \sqrt{\frac{k}{m}}$

• f is the corner's ride frequency
• k is the suspension's spring rate
• m is the sprung mass supported by the corner

Sources

• Natural Frequency, Ride Frequency and their Influence in Suspension System Design