Calculate wheel rate from spring rate and motion ratio, including installation angle and helper springs, plus ride frequency from corner weight.

Linear, constant-geometry estimate. Basic motion ratio includes installation angle; the separate-angle mode uses a lever ratio before angle correction.

Measured travel ratio already includes spring angle.

Wheel Rate Formula

The following two example problems outline the steps and information needed to calculate the Wheel Rate.

WR = K ร— Mยฒ
  • Where WR is the Wheel Rate (e.g., lbf/in, N/m)
  • K is the spring rate (same force/length units as WR) 
  • M is the motion ratio (actual spring compression รท vertical wheel travel near ride height, dimensionless). A separately mounted shock may have a different ratio.

To calculate the wheel rate, multiply the spring rate by the motion ratio squared (with motion ratio defined as actual spring compression รท wheel travel). This measured ratio already includes installation angle. In the separate-angle mode, enter the geometric lever ratio before projection onto the spring axis; do not count the angle twice. Two series springs use their combined rate only while both deflect, not after a helper becomes coil-bound.

How to Calculate Wheel Rate?

The following example problems outline how to calculate Wheel Rate.

Example Problem #1:

  1. First, determine the spring constant (lbf/in).
    • The spring constant (lbf/in) is given as 400.
  2. Next, determine the motion ratio (dimensionless).
    • The motion ratio (spring/shock travel รท wheel travel) is provided as 0.80.
  3. Finally, calculate the Wheel Rate using the equation above: 

WR = K * M^2

The values provided above are inserted into the equation below and computed.

WR = 400 * 0.80^2 = 256.00 (lbf/in)

Example Problem #2: 

For this problem, the variables required are provided below:

spring constant (lbf/in) = 550

motion ratio (spring/shock travel รท wheel travel, dimensionless) = 0.70

Test your knowledge using the equation and check your answer with the calculator.

WR = K * M^2 = 550 * 0.70^2 = 269.5 lbf/in