History
One theory of the advent of the unicycle stems from the popularity of the penny-farthing (or "Ordinary") during the late 19th century. Since the pedal and cranks were connected directly to the front axle, the rear wheel would go up in the air and the rider would be moved slightly forward. Many penny-farthing owners discovered they could dispense with the frame and just ride the front wheel and handlebars. Evidence for this theory of development can reportedly be found in pictures from the late 19th century showing unicycles with large wheels.
Over the years, unicycle enthusiasts have inspired manufacturers to create new designs, such as seatless ("ultimate wheel") and tall ("giraffe") unicycles. During the late 1980s some extreme sportsmen took an interest in the unicycle and started off-road unicycling.
Types of unicycles
<dl><dt></dt><dt>Freestyle unicycles</dt><dd>Generally used for flatland skills and routines. Usually have a relatively high seatpost, a narrow saddle, a squared fork (used for one-footed tricks), and square taper cranks and hub, as they usually do not need to withstand as much pressure as afforded by more expensive splined cranks. These unicycles are used similarly to flatland bicycles. Some examples of freestyle unicycles include Miyata, Nimbus, Schwinn, and Semcycle brands. This type of unicycle is often less expensive than some other types due to the less robust construction. Wheel size is usually 20 inches (510 mm), but smaller riders may use 16-inch (410 mm) or 12-inch (300 mm) unicycles. Some people prefer 24-inch (610 mm) wheels.</dd><dt>Trials unicycles</dt><dd>Designed for unicycle trials, trials 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. Most modern trials unicycles include splined hubs and cranks, which are stronger and less prone to damage in the event that the crank bolts come loose while riding. This feature was less common in the past, when splined hubs were much more expensive. Many trials unicycles also have wide, 19- or 20-inch (510 mm) knobby tires to absorb some of the impact on drops.</dd><dt>Offroad unicycles ("munis") </dt><dd>"MUni" or "muni" is an abbreviation for mountain unicycling. MUnis have many of the same components as trials unicycles, but have a few key differences. Usually, the tire diameters on mountain unicycles are either 24 or 26 inches (660 mm), allowing the rider to more easily roll over obstacles such as roots and rocks. The seat is also thicker and more comfortable on MUnis to compensate for the rough terrain. Brakes are sometimes used for steep descents.</dd><dt>Touring unicycles</dt><dd>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 to achieve such high candances as direct-drive wheels, but demand greater force per pedal stroke.</dd></dl>
Speed
The pedals of a typical unicycle (e.g. not a giraffe or guni) connect directly to the wheel. This means that there are no gears to shift and provides a very direct feel of the wheel contact with the ground. It also means that wheel size is a major factor in unicycle speeds:
<table title="wikitable mceItemTable"><tbody><tr> <th>Wheel size</th> <th>Avg</th> <th>High</th> </tr> <tr align="right"> <td>20"</td> <td>4 mph (6.4 km/h)</td> <td>8 mph (13 km/h)</td> </tr> <tr align="right"> <td>24"</td> <td>5 mph (8.0 km/h)</td> <td>10 mph (16 km/h)</td> </tr> <tr align="right"> <td>29"</td> <td>7 mph (11 km/h)</td> <td>14 mph (23 km/h)</td> </tr> <tr align="right"> <td>36"</td> <td>11 mph (18 km/h)</td> <td>22 mph (35 km/h)</td></tr></tbody></table>
