Gulak drew up a plan for an all-electric unicycle that would emit no fumes and, he figured, be easier to weave through crowded streets than a standard two-wheeler. To give the ride more stability, he put the wheels side-by-side just an inch apart and directly under the rider, who accelerates by leaning forward, as he would on a Segway. When the rider leans into a turn, the inside wheel lifts and the outside wheel lowers, so both stay firmly on the ground.