Unicycle

A unicycle is a one-wheeled, human powered vehicle. Unicycles are similar to, but less complex than, bicycles.

Unicycles comprise a few key parts: the wheel and axle, the frame, the seat, and cranks and pedals. The wheel is the main part of the unicycle; it is essentially a bicycle wheel with a special hub so that the frame and cranks can attach to the side. The frame sits above the wheel, and the seat is located on top of the frame.

Unicycles are thought to descend from the penny-farthing bicycles of the late 19th century. These bicycles had a large wheel in front, to which the pedals were attached, and a much smaller wheel behind for balance. When these bicycles hit a bump, the rear wheel would come off the ground, forcing the rider to balance on one wheel. Early unicycle photographs, which show unicycles with very large wheels, support this explanation.

Unicycles are more difficult to ride than bicycles. They require the rider to maintain balance in two dimensions rather than one, and with their slower speeds their motion has less gyroscopic assistance for maintaining stability.

Unicycles have traditionally had circus connotations, but in recent years unicycles have gained a following as a means of everyday transportation. Unicycling has also gained popularity as a sport. The bi-annual world championship UNICON[?] holds Unicycle races. Riding a unicycle in off-road conditions is known as mountain unicycling, which is similar to mountain biking. In unicycle trials the unicyclist aims to negotiate a series of obstacles without any part of the rider touching the ground.

Variations on the standard unicycle include:

• Giraffe unicycles: tall, chain-driven unicycles.
• Mountain unicycles: unicycles made for the sport of mountain unicycling.
• Kangaroo unicycles[?]: unicycles with an off-center wheel and cranks that face the same direction. The rider of a kangaroo unicycle appears to be hopping about like a kangaroo, hence the name.
• Ultimate wheel[?]: a unicycle with no frame or seat, just a wheel, cranks, and pedals.
• Impossible wheel: a wheel with pegs sticking out for the rider to stand on. Theoretically, this works like log-rolling.

Balancing a robotic unicycle forms an interesting problem in control theory.

External Links

• International Unicycling Federation (http://www.unicycling.org/iuf/)
• IUF Skill Levels (http://www.unicycling.org/iuf/levels/)
• Unicycling Society of America (http://www.unicycling/usa)