California Vehicle Code (38506 CVC) prohibits double riding on ATVs on public lands, unless the ATV is designed to carry a passenger.
ATVs are rider active, designed for a single rider who uses the entire seat while riding. A rider will use the entire seat area to negotiate turns and facilitate movement while going up or down hills. A passenger restricts the rider’s movement, interfering with the balance and handling of the vehicle. How? A passenger becomes a liability when traveling up a hill, making the vehicle too heavy in the back, and potentially causing it to flip backwards. Riders typically shift their weight to the front of the vehicle when ascending a hill. Conversely, a rider will shift their weight to the back of the vehicle when descending a hill, so the machine will not end over itself. As needed, riders also shift their weight either left or right when negotiating turns to keep the machine from rolling.