Theories about truck geometry assumes that the truck pivots exactly about the pivot axis. The roll center (the
X-axis which the board / baseplate rotates about the hanger / wheels) is the intersection where a vertical line
above the axle meets the pivot axis. While this is useful to demonstrate the effects of things like axle offset, it
appeared that there are many other contributing variables. According to conventional truck geometry theory,
when riding a 45 degree truck, there is a 1:1 relationship between board lean and truck turning. Based on this,
if you lean 15 degrees, each truck turns the same 15 degrees. As we began to study truck dynamics and test
results proved the theories to be oversimplifications. Truck dynamics are far more complicated than we may
have been led to believe.
Testing on specialized fixtures proved that trucks do not pivot exactly at the pivot axis, and that there were
several other variables that affected the way a truck behaves. The largest contributor besides geometry was the
design of the bushing seat and the interaction between it and the bushings.
On-board filming confirmed that the interaction between the bushing and the hanger bushing seat causes the
hanger to shift, providing a responsive, fluid feel. We experimented with different bushing seat designs, refining
handling, eventually leading to this model.