Carvology - Spring Engineering

Don’t confuse Seismic with spring-based trucks from the 1970s!

Spring Engineering

A New Approach to Springs
In the 1970s, several truck manufacturers briefly tried using coil springs. Trucks like the X-Caliber and the Speed Spring didn’t succeed because they were too heavy, too squirrelly, and/or too complex (and thus vulnerable to damage and breakdown).

Seismic trucks incorporate springs, too, but the similarities end there. Unlike the poorly-constructed spring-based gizmos seen in the 1970s, they’re light, stable, simple to handle, and durable.

Our custom-made springs lie at a perfect 90° angle to the pivot axis, so they provide direct, precise opposition to the hanger’s motion. To prevent buckling, Seismic springs pivot at both ends on ball-and-socket joints. Small inner springs expand when necessary to keep those joints working smoothly. Also, Seismic trucks were patented long before scaled-up, stripped-down imitations began appearing on off-road skateboards and surfing cross-trainers.

Calculating the Spring Rates
Seismic springs are custom-made to the most exacting specifications. The spring rates (the power of the spring throughout its compressive range) are calculated using a set of extremely complex mathematical equations and the most advanced theories of skateboarding bio-dynamics. The inventor, Dan Gesmer, spent over ten years deriving and refining these equations, which can only be efficiently solved with mathematical analysis software. Click here to see article: "Mathmatics Steers Skateboards Into 21st Century"

Through kinematic and force-vector analysis, Dan determined the precise mathematical relationships amongst every variable relevant to truck performance. These variables include numerous key dimensions of the truck itself; carefully-measured average values for wheel diameter, wheel clearance, wheel base, deck width, and skater size; the tilt angle of the skateboard deck; the lean angle of the skater’s body; the lateral distribution of the skater’s weight; forward velocity; and the coefficient of friction between wheels of average hardness and average riding surfaces. Through careful study and scientific experiment (including video analysis of skaters making turns at varying speeds), Dan developed original theories on the relationship of turning radius with velocity, knee bend, and deck weighting. He also corroborated his research with two American professors of engineering who may be the only ones in the world to have studied the dynamics of skateboard turns.