A unicycle is a vehicle that touches the ground with only one wheel. The most common variation has a frame with a saddle, and has a pedal-driven direct drive. A two speed hub is commercially available for faster unicycling. Unicycling is practiced professionally in circuses, by street performers, in festivals, and as a hobby. Unicycles have also been used to create new sports such as unicycle hockey. In recent years, unicycles have also been used in mountain unicycling, an activity similar to mountain biking or trials.
US patents for single-wheeled ‘velocipedes’ were published in 1869 by Frederick Myers and in 1881 by Battista Scuri.
Unicycle design has developed since the Penny Farthing and later the advent of the first unicycle into many variations including: the seatless unicycle (“ultimate wheel”) and the tall (“giraffe”) unicycle. During the late 1980s some extreme sportsmen took an interest in the unicycle and modified unicycles to enable them to engage in off-road or mountain unicycling, trials unicycling and street unicycling.
Bicycles, tricycles and quadracycles share (with minor variations) several basic parts including wheels, pedals, cranks, forks, and the saddle with unicycles. Without a rider, unicycles lack stability – however, a proficient unicyclist is usually more stable than a similarly proficient rider on a bicycle as the wheel is not constrained by the linear axis of a frame. Unicycles usually, but not always, lack brakes, gears, and the ability to freewheel. Given these differences, the injuries that can occur from unicycle use tend to be different from that of bicycle use. In particular, head injuries are significantly less likely among unicycle use compared to bicycle use.
Unicycles have a few key parts: the wheel (which includes the tire, tube, rim, spokes, hub and axle), the cranks (which attach the pedals to the wheel hub), the hub (connects the spokes to a central point and also transfers pedaling power to the wheel), pedals, a fork-style frame, the seatpost, and the saddle (the seat of the unicycle).
The wheel is usually similar to a bicycle wheel with a special hub designed so the axle is a fixed part of the hub. This means the rotation of the cranks directly controls the rotation of the wheel (called direct drive). The frame sits on top of the axle bearings, while the cranks attach to the ends of the axle, and the seatpost slides into the frame to allow the saddle to be height adjusted.
Used for long distances, these unicycles are specially made to cover distances. They have a large wheel diameter, between 26 and 36 in., so more distance is covered in less pedal rotation. A 36" unicycle made by the Coker Tire company started the big wheel trend. Some variations on the traditional touring unicycle include the Schlumpf “GUni” (geared unicycle), which uses a two-speed internal fixed-geared hub. Larger direct-drive wheels tend to have shorter cranks to allow for easier cadence and more speed. Geared wheels, with an effective diameter larger than the wheel itself, tend to use longer cranks to increase torque as they are not required.
Designed for unicycle trials, these unicycles are stronger than standard unicycles in order to withstand the stresses caused by jumping, dropping, and supporting the weight of the unicycle and rider on components such as the pedals and cranks. Many trials unicycles also have wide, 19- or 20-inch (510 mm) knobby tires to absorb some of the impact on drops.
Generally used for flatland skills and freestyle routines, freestyle unicycles typically have a relatively high seatpost, a narrow saddle, and a squared fork (used for one-footed tricks). These unicycles are used similarly to flatland bicycles. Wheel size is usually 20 inches (510 mm), but smaller riders may use 16-or-12-inch (410 or 300 mm) unicycles. Some people prefer 24-inch (610 mm) wheels.
Mountain unicycling (abbreviated to muni or mUni) consists of riding specialized unicycles on mountain bike trails or otherwise off-roading. Mountain unicycles have thicker, wider tires for better traction. Riders may occasionally lower air pressure for increased shock absorption. Many riders choose to use long cranks to increase power when riding up hills and over rough terrain. A disc brake is sometimes used for descents; the brake handle is attached to the underside of the handle on the front of the saddle.
Traditionally, unicycling has been seen as a circus skill which has been performed at events to entertain the public in the circus or during parades, carnivals or street festivals. Recent developments in the strength and durability of bicycle (and consequently unicycle) parts have given rise to many new activities including trials unicycling and mountain unicycling. Unicycling is arguably now as much a competitive sport and recreational pursuit as an entertainment activity.
Perhaps the oldest form of unicycling, traditional freestyle riding is based on performance. Freestyle tricks and moves are derived from different ways of riding the unicycle, and linking these moves together into one long flowing line that is aesthetically pleasing. Competitions look very similar to figure skating.
Along with freestyle it is a performance style of unicycling. Often employed by clowns and other circus skills performers. Comedy unicycling exaggerates the perceived difficulty of riding a unicycle to create a comedic performance.
Street unicycling as a style involves riders using a combination of objects found in urbanized settings (such as ledges, handrails, and stairs) to perform a wide variety of tricks. Many tricks are similar to those performed in other extreme sports, such as BMX and skateboarding.
Often abbreviated to “MUni,” off-road or mountain unicycling involves riding on rough terrain and has developed as a form of unicycling in recent years.
This style concentrates on distance riding. With a 29-or-36-inch (740 or 910 mm) wheel cruising speeds of 10 to 15 mph (24 km/h) or more can easily be reached.
This style of unicycling is similar to freestyle in that various tricks and movements are performed on flat ground.