The ordinary or penny-farthing is an early model of bicycle, produced largely in England and the United States in the mid to late 19th century.
The earliest bicycles had pedals mounted directly on the front wheel. In order to increase speeds in the absence of any practical method of gearing, larger and larger wheels were built, culminating in the classic penny-farthing where the wheel could be 1.5m (60") or more in diameter. The name refers to the English penny and farthing coins of the time, the former being large and the latter unusually small. Other popular names include high-wheeler, high bicycle and boneshaker, although this last generally referred to any early bicycle before the invention of the pneumatic tyre.
It had only a brief vogue, arriving and departing within a couple of decades, but it has caught the imagination as visually representing the late Victorian era. This brief lifetime coincided almost exactly with the birth of cycle sport.
The ordinary is a direct-drive bicycle, meaning that the cranks and pedals are affixed directly to the hub. Instead of using a relatively complex and heavy gear system to multiply the revolutions of the pedals, the driven wheel was enlarged to its maximum radius -- up to a length close to the rider's inseam -- to increase the maximum speed. This shifted the position of the rider upward, placing him nearly on top of the wheel. This meant that the rider's feet could not reach the ground while riding, making it effectively little more than a unicycle with an extra wheel for stability.
The frame is a single tube following the circumference of the front wheel for around 1/4 arc, then diverting at a tangent to a fork in which is mounted a small trailing wheel. A mounting peg is attached above the rear wheel. The front wheel is mounted in a rigid fork with little if any trail. A spoon brake is usually fitted on the fork crown, operated by a lever from one of the handlebars. The bars are usually moustache shaped, dropping down from the level of the headset. The saddle mounts on the frame somewhat less than 0.5m (18") behind the headset.
Mounting a wheel is a process requiring some skill. One foot is placed on a small peg on the frame above the back wheel. The rider then grasps the handlebar, scoots using the other foot, and when sufficient speed has been gained to effect balance, lifts himself (almost all high-wheel riders were and are men) into the saddle.
Although very stable due to the pendulum effect, the penny-farthing was notoriously prone to accidents. To slow and stop a high wheel, as with a fixed gear bicycle, the rider applies a backwards pedaling motion, augmented by use of a spoon-shaped brake pressing on the tyre. The center of mass being both high and not far behind the contact point of the front wheel meant that any attempt to stop suddenly, or any collision with a large pothole or other obstruction, would be likely to send them flying over the handle bars (known as "taking a header" or "coming a cropper"). On long downhill stretches it was recommended that riders take their feet off the pedals and hook them over the handlebars, so that in case of a crash they would land (hopefully) on their feet. This made for quick descents but left almost no chance of stopping should the need arise.
The appearance of the bike, with the one wheel dominating, led to their riders being referred to in America especially as "wheelmen", a name which lived on for nearly a century in the League of American Wheelmen until it was renamed the League of American Bicyclists. Clubs of racing cyclists would wear uniforms comprising peaked caps, tight jackets and knee-length breeches, with leather shoes, the caps and jackets displaying the club's colors.
Some tremendous feats of balance were reportedly exhibited by high wheel riders, including negotiating a narrow bridge parapet for a dare.
The high-wheeler lives on in spirit in the gear inch units used by cyclists to describe gear ratios. These are generally calculated by multiplying the wheel diameter by the number of teeth on the chain wheel and dividing by the number of teeth on the sprocket. The result, in inches, is the equivalent diameter of a wheel (for example a typical bike might have a 26" wheel, a 48T chain ring and a 14T sprocket, giving an 89" gear). A 60" gear, the largest reasonably practicable size for a high-wheeler's front wheel, is nowadays a middle gear of a typical utility bicycle, while top gears on many bikes exceed 100".
Ironically the nephew of one of the men responsible for the popularity of the penny-farthing was also largely responsible for its death. James Starley had originally built the Aerial high-wheeler in 1870, but this was a time of rapid innovation (almost all recent innovations in bicycle design are actually reinventions of late 19th Century experiments) and small-scale chain drives became practical within ten years, making it possible to achieve the same speeds without the need for the large wheel. In 1885, James Starley's nephew John Kemp Starley launched the Rover Safety Bicycle, so called because the rider was seated much lower down and much further behind the front wheel contact point. Over the next ten to fifteen years the ordinary in all its forms practically vanished.
Today there are enthusiasts who ride restored ordinaries, and even a few who will build a new one, but the shape of the Rover Safety and its development of the diamond-framed bicycle has come to dominate the public perception of what a bicycle looks like. Only historically-aware cyclists generally understand that the term "ordinary bicycle" does not mean a standard diamond-frame.