Patent ID: 8152191

Claim:
A suspension system comprising: a front frame connected to a front wheel; a shock absorber pivotally connected to the front frame and having a preset pressure, wherein the shock absorber is adjustable to set the preset pressure; a rear frame connected to a rear wheel supported by a ground contact point, and structurally configured to maintain an instantaneous center point of movement of the rear frame relative to the front frame within an angle range of about 45°±15° relative to the ground contact point when the rear frame moves relative to the front frame; a drive unit having a crankshaft mounted directly to the front frame; wherein the front and rear frames are arranged to guide a virtual pivot point, which represents a rotating center of a center point of the rear wheel when the rear wheel moves upwardly relative to the front frame, to move from a first position, which is located rearward of a center of the crankshaft, to a second position that is rearwardly spaced away from the first position when the rear wheel moves away from a ground surface.