Unicycle

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

1 Construction
2 Riding
3 History
4 Theory
5 Recent developments
6 Unicycle Hockey
7 Variations
8 External links

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Construction

Unicycles are comprised of a few key parts: the wheel, which includes the tire, tube, rim, spokes, hub and axle; the cranks and pedals; the frame; the seatpost; and the saddle. The wheel is the main part of the unicycle; it is basically a bicycle wheel with a special hub that doesn't freewheel, which means the axle can't turn independently of the hub. This makes it so the rotation of the cranks directly control the rotation of the wheel. This is called direct drive. The frame sits on top of the axle, and cranks attach to the ends of the axle. The seatpost links the frame to the saddle. Some modern unicycles are using gears in the hub to increase riding distance, but the basic construction remains the same: the seat is located on the frame and the frame sits above the wheel.

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Riding

Riding a unicycle typically takes between 5 and 10 hours of practice time to learn to ride forwards with some control, and several more hours to turn, unless one has an inherent natural ability for riding one. Mastery of the skill however takes a lifetime as there are always new things to learn. At slower speeds steering motions need to be exaggerated to achieve the same angle of turn as at higher speed. The biggest problem for beginners is mounting unaided (freemounting) and this can take a number of days to learn; due to the number of different mounts it can take a long time to learn them all.

Idling is when a unicyclist maintains their position by moving the pedals forwards and backwards between the 5:00 and 7:00 positions.

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

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History

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, or the rider attempted to slow suddenly, 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 have long been a component of traditional circus performance, often with refinements such as juggling while riding, or riding across a tightrope.

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Theory

A unicycle is a Nonholonomic system because its outcome is path-dependent.

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Recent developments

In recent years unicycles have gained a following as a means of everyday transport. Unicycling has also gained popularity as a sport. The annual national NAUCC and bi-annual world championship UNICON hold Unicycle races. Riding a unicycle in off-road conditions is known as mountain unicycling, commonly called MUni. In unicycle trials the unicyclist aims to negotiate a series of obstacles, usually done by hopping, without any part of the rider touching the ground or using the hand to grasp onto an obstacle. Freestyle Unicycling contains a style of tricks similar to those seen in skateboarding, aggressive in-line skating, BMX, and freestyle biking including jumps, spins, and grinds. The newest style of riding is street unicycling. It is a mix of unicycle trials and freestyle unicycling. It consists of stair riding, jumps, grinds, spins, and rail riding usually on urban obstacles.

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Unicycle Hockey

Unicycle Hockey is a growing niche sport, with 5 members on each team and played with ice-hockey sticks and a street hockey ball or a deadened tennis ball as favoured by the Germans (some clubs have been known to use a puck). A league operates in Germany/Switzerland; in other countries such as Great Britain clubs typically meet and play individually, and competitively at Uni and club meets and conventions. The world championships sometimes take place at the biennial UNICON event.

International rules: http://www.mpch-mainz.mpg.de/~sander/uni/iuf_03e.html

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Variations

Giraffe unicycles: tall, chain-driven unicycles.
Mountain unicycles or munis: unicycles made for the sport of mountain unicycling, usually with thicker wheels.
Kangaroo unicycles: unicycles with an off-center wheel and cranks that face the same direction.
Trials unicycle: unicycle meant for drops and hops, usually with a smaller wheel diameter, for more controllability.
Ultimate wheel: a unicycle with no frame or seat, just a wheel, cranks, and pedals.
Impossible wheel:(Also known as a BC wheel) a wheel with pegs or metal plates sticking out for the rider to stand on.
Coaster Uni: a unicycle where the hub freewheels, giving a cross between a traditional unicycle (where one pedals to maintain forward velocity and balance) and an impossible wheel (where instead of standing on pegs or platforms, the rider stops pedalling and stands on the pedals.)
Multi-wheeled unicycle: Still a unicycle since the wheels are stacked on top of each other so only one touches the ground. The wheels are linked together by chains or friction.
A quick list of other variations: Tandem, Recumbent, Hydraulic Giraffe, Unibike, Motorized unicycle [1], Suicycle
Monowheel (also known as a monocycle) : a large wheel in which the rider sits inside (like a hamster wheel) and either pedals an internal drive or is motorized. It is not plagued by the normal unicycle balance problems because of the greater gyroscopic properties and lower center of mass.
Eunicycle : a computer-controlled self-balancing unicycle.