A bicycle or bike, can be defined generally as a pedal-driven human-powered vehicle with two wheels attached to a frame, one behind the other. The International Union of Cycling adds the provision that the seat be more or less above the pedals, thus excluding recumbent bicycles.
The basic shape and configuration of the bicycle's frame, wheels, pedals, saddle, and handlebars have hardly changed since the first chain-driven model was developed around 1885, although many important details have since been improved, especially since the advent of modern materials and computer-aided design. These have allowed for a proliferation of specialized designs for individuals who pursue a particular type of cycling.
Kirkpatrick Macmillan, an inventor, was born in Keir (Dumfries and Galloway) in 1812 where he worked as a blacksmith at Courthill Smithy. He developed the first rear-wheel driven safety bicycle 1842, which allowed the rider to power the bicycle by means of pedals attached to levers and then attached to the rear wheel.
Macmillan held a variety of positions as a young man, before settling into the trade himself in 1824 and eventually returning to work with his father. At around that time he saw a hobbyhorse being ridden along a nearby road, and decided to make one for himself. Upon completion, he realised what a radical improvement it would be if he could propel it without putting his feet on the ground. Working at his smithy, he completed his new machine in around 1839.
This first pedal bicycle was propelled by a horizontal reciprocating movement of the rider's feet on the pedals. This movement was transmitted to cranks on the rear wheel by connecting rods; the machine weighed almost exactly half a hundredweight and the physical effort required to ride it must have been considerable. Nevertheless, he quickly mastered the art of riding it on the rough country roads, and was soon accustomed to making the fourteen-mile journey to Dumfries in less than an hour. His next exploit was to ride the sixty-eight miles into Glasgow in June 1842. The trip took him two days and he was fined five shillings for causing a slight injury to a small girl who ran across his path.
He never thought of patenting his invention or trying to make any money out of it, but others who saw it were not slow to realize its potential, and soon copies began to appear and be sold for six or seven pounds. Gavin Dalzell of Lesmahagow copied his machine in 1846 and passed on the details to so many people that for more than fifty years he was generally regarded as the inventor of the bicycle. However, Macmillan was quite unconcerned with the fuss his invention had prompted, preferring to enjoy the quiet country life he was used to. A plaque at the family smithy at Courthill reads, "He builded better than he knew" - a pun based on his unwillingness to seek fame and fortune for his momentous invention.
The bicycle has affected history considerably, in both the cultural and industrial realms. In its early years, bicycle construction drew on pre-existing technologies; more recently, bicycle technology has, in turn, contributed ideas in many new and emerging technologies.