Evolution of the Original Seismic Technology Throughout skateboarding’s brief history, nearly every truck on the market has been based on 1930’s roller-skate technology. Skateboard manufacturers have improved materials and construction, but the outdated design standard suffers from sloppy geometry, poor steering control, and sluggish axle rebound. Freestyle innovator and Yale graduate Daniel Gesmer (profiled in the widely-seen 1988 Powell-Peralta video Public Domain) wasn’t satisfied with the old roller-skate technology. For his unique artistic style, he needed trucks with greater power, sensitivity, and control. Determined to systematically rectify the problem, in 1983 Dan painstakingly developed a precise mathematical model of conventional trucks’ steering response. Though studying philosophy and psychology at Yale, he had picked up enough math and physics for the task at hand. Excerpts from Dan’s 1984 analysis of skateboard steering dynamics. Special thanks to ice skate engineering guru Sidney Broadbent.

Like in the mid-1970s and mid-1980s, all-around skateboarding is once again enjoying a renaissance. Approaches that were considered “alternative” throughout most of the 1990s – such as longboarding, slalom, downhill, all-purpose cruising, and flatland freestyle – are now mainstream. Seismic Skate Systems is proud to have helped propel that movement. Since 1994, when turning on skateboards was considered highly unfashionable, our trucks have offered the world’s most progressive carving performance. For even longer, we’ve pro-actively supported carving, racing, and freestyle by writing for magazines, lobbying movers-and-shakers in mainstream skateboarding, and helping produce elite competitions.

Two years after graduating, and at the height of his professional skateboard career, Dan teamed up with a machine tool builder in his hometown of Rockford, Illinois. Together they developed an assortment of prototypes for advanced trucks, all incorporating metal springs set at a 90-degree angle to a fixed steering axis. The goal was to create sharper steering with better energy return.

Simultaneously, Dan began to expand his mathematical model of skateboard steering performance to encompass control dynamics. Through kinematic and force-vector analysis, he modeled the relationships between spring power and the skateboarder’s motion forces, determining the precise mathematical relationships amongst literally 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 deck; the lean angle of the rider; the lateral distribution of the skater’s weight; forward velocity; and the coefficient of friction between wheels of average hardness and average riding surfaces.

After his Illinois partner’s fortunes took a turn for the worse, Dan joined forces with a group of German manufacturers. A four-year period of intensive development work began.