THE LEVERAGE RATIO CONCEPT

"Back in the day" shocks were mounted at the rear axle and life for the suspension tuner was simple. Just setup the suspension based on bike and rider weight and type of use. Along came long travel and linkages and life became a little more complicated.

What if the suspension could be soft on the little bumps and stiff on the big bumps? This is the main idea behind linkages. Linkages can make the Leverage change through the stroke.

Leverage Ratio is defined as:

LR = Change in Wheel Travel / Change in Shock Travel
      = Shock Force / Wheel Force

By measuring Wheel Travel and Shock Travel simultaneously (one transducer mounted vertically at the wheel and one mounted on the shock), we can calculate the Leverage Ratio with the LR Software.

Don't expect to be an expert by doing one Leverage Ratio Curve. When I did my first one back in 1980 I looked at it and thought, "huh?" Now, after doing hundreds of curves for both dirt and street, they make a lot more sense.

Rear Wheel Force Curves

From Leverage Ratio we can determine Rear Wheel Force if we know the Spring Rate and the Preload (Rear Wheel Force = the force created by the Shock Spring at the rear wheel). Using "Compare LR Files", up to 4 different wheel force curves can be simultaneously viewed. Spring rate and preload can be changed to show the result different settings will have on wheel force.

See Help 8.5.2

Convert Wheel to Shock (or Shock to Wheel)

Leverage ratio files can be used to convert ShockClock recordings. For instance, a ShockClock recording taken from the rear of a bike can be converted into "as if recorded from the Shock". For tuners who want to know shock velocities, but are unable to mount a transducer directly to the shock.

See Help 8.6

Leverage Ratio Kit

The Leverage Ratio Kit (MSLR 01 - $249.99) includes the Leverage Ratio Software (unlock code) and Hardware to convert a standard Transducer into a Leverage Ratio Transducer. It requires a Pro Kit (2 ShockClocks) so you can measure rear wheel travel and shock travel at the same time.


Have Fun,
Paul Thede
President, Race Tech

P.S. If you want to understand this better we have Suspension Seminars 951.279.6655.

Click on the following link to view the Leverage Ratio Software Help Guide.

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