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This mountain bicycle features oversized tires, a sturdy frame, front shock absorbers, and handlebars oriented perpendicular to the bike's axis
"Bicycle" may also refer to Bicycle Playing Cards.

A bicycle, or bike, is a pedal-driven land vehicle with two wheels arranged in line. First introduced in 19th century Europe, it evolved quickly into its current design. With over one billion in the world today, bicycles provide the principal means of transportation in many regions and a popular form of recreation in others.

History

Main article: History of the bicycle

No specific time or person can be identified with the invention of the bicycle. Its earliest known forebears were called velocipedes, and included the scooter-like dandy horses of the French Comte de Sivrac, dating to 1790, and German tax collector Karl von Drais, who rode his 1816 machine on his rounds. All the aforementioned were literally pushbikes, in that they were powered by the action of the rider's feet against the ground. A Scottish blacksmith, Kirkpatrick MacMillan, is credited with adding a treadle drive mechanism in 1840, for the first time enabling the rider to lift his feet off the ground.

In the 1850s and 1860s, Frenchman Ernest Michaux and his pupil Pierre Lalloment placed pedals on an enlarged front wheel. Their creation, aptly called the Boneshaker, featured a heavy steel frame on which were mounted wooden wheels with iron tires. The boneshaker was further refined by James Starley in the 1870's. He mounted the seat more squarely over the pedals, so that the rider could push more firmly, and further enlarged the front wheel to increase the potential for speed. Shod with soild rubber tires, his machine became known as an ordinary. British cyclists likened the disparity in size of the two wheels to their coinage, nicknaming it the penny-farthing. This model was difficult to ride however, and the high seat and poor weight distribution made for dangerous falls.

The dwarf ordinary which followed addressed some of these faults, by reducing the front wheel diameter and setting the saddle farther back. Pedaling was accomplished by levers or off-set pedals, and gearing was added, thus compensating for speed loss. However, having to both pedal and steer via the front wheel remained a problem. Starley's nephew, J. K. Starley, J. H. Lawson, and Shergold solved this problem by introducing rear wheel drive, using a chain. Starley's 1885 Rover is usually described as the first recognisably modern bicycle. These dwarf safeties, or safety bicycles, were so-named for their lower seating height and better weight distibution. Soon the seat tube was added, creating the double-triangle, diamond frame of the modern bike.

Bicycle in Victorian Plymouth, with a predecessor of the Starley diamond-frame

While the Starley design was much safer, the return to a smaller wheels made for a bumpy ride. However, subsequent innovations increased comfort and ushered in the 1890s Golden Age of Bicycles. In 1888 Scotsman John Boyd Dunlop introduced the pneumatic tire, which soon became universal. Shortly thereafter the rear freewheel was developed, enabling the rider to coast without the pedals spinning out of control. This refinement led to the 1898 invention of coaster brakes. Derailleur gears and hand-operated, cable-pull brakes were also developed during these years, but were slow to be adopted by casual riders. By the turn of the century, bicycling clubs flourished on both sides of the Atlantic, and touring and racing were soon the rage.

Successful early bicycle manufacturers included Englishman Frank Bowden and German builder Ignaz Schwinn. Bowden started the Raleigh company in Nottingham in the 1890s, and soon was producing some 30,000 bicycles a year. Schwinn emigrated to the United States, where he founded a similarly successful company in Chicago in 1895. Schwinn bicycles soon featured widened tires and spring-cushioned padded seats, sacrificing some efficiency for increased comfort. Facilitated by connections between European nations and their overseas colonies, European-style bicycles were soon available worldwide. With mass production and reduced prices, by the mid-20th century bicycles had become the primary means of transportation for millions of people around the globe.

In many western countries the use of bicycles leveled off or declined as motorized forms of transport became affordable and as car-centered policies lead to an increasingly hostile road environment for bicycles. In North America, bicycle sales declined markedly after 1905, to the point where by the 1940s, they had largely been relegated to the role of children's toys. In other parts of the world, such as China, India, and some European countries such as the Netherlands, Germany, and Denmark, the traditional utility bicycle remains a mainstay of transportation, their design only gradually changing to incorporate hand-operated brakes and the internal hub gears alowing up to 7 speeds.

In North America, increasing consciousness of physical fitness and environmental preservation spawned a renaissance of bicycling in the late 1960s. Bicycle sales in the United States boomed, largely in the form of the racing bicycles long used in such events as the hugely popular Tour de France. First these cycles, and then the mountain bikes which followed, virtually eliminated the three-speed bicycle from American roads. These specialized designs led many American recreational cyclists to demand a more comfortable and practical product. Manufacturers responded with the hybrid bicycle.

Technical aspects

Reflectors for night riding are one of many available safety accessories

The Vienna Convention on Road Traffic considers a bicycle a vehicle and a person controlling a bicycle a driver. The traffic codes of many countries reflect these definitions and demand that a bicycle satisfy certain legal requirements, including licencing, before it can be used on public roads. In many jurisdictions it is an offence to use a bicycle that is not in roadworthy condition and which does not have functioning front and rear brakes. In some places, bicycles must have functioning front and rear lights or lamps. As some generator or dynamo-driven lamps only operate while moving, rear reflectors are frequently also mandatory. Since a moving bicycle makes very little noise, in many countries bicycles must have a warning bell for use when approaching pedestrians, equestrians and other bicyclists.

Construction and parts

Modern bicycles retain the same diamond frame design, incorporating a pair of contiguous triangles, introduced a century ago. The front wheel attaches to the fork, which in turn links via bearings to the head set on the front of the frame. The handle bars attach atop the headset via a stem. Some mountain bicycles substitute a fork-like system on the rear as well, adding suspension systems for a smooth ride over rough ground. The pedals rotate cranks which fit into the bottom bracket. Attached to the crank is the chainring which drives the chain, which in turn rotates the rear wheel. Within this drive train may be interspersed various gearing systems, described below, which vary the number of rear wheel revolutions produced by each turn of the pedals.

Since cyclists' legs can only produce a limited force and work best at specific speeds, or cadences, a variable gear ratio allows one to maintain an optimum pedaling speed while covering varied terrain. The gear systems are hand-operated, via cables, and are of two types. Internal hub gearing works by planetary or epicyclic gearing, in which the outer case of the hub gear unit turns at a different speed relative to the rear axle depending on which gear is selected. External gearing involves derailleurs, which can be placed on both the front chainring and on the rear cluster or cassette, to push the chain to either side. The sides of the gear rings catch the chain, pulling it up onto their teeth to change gears. Road bicycles have close set multi-step gearing, which allows very fine control of cadence, while three-speed or utility cycles offer a lesser number of more widely spaced speeds. Mountain bikes may offer an extremely low gear to facilitate climbing slowly on steep hills. Internal hub gearing still predominates in some regions, particularly on utility bikes, whereas in other regions external derailleur systems predominate.

Three handlebar styles are common. Touring handlebars, the norm in Europe and elsewhere until the 1970s, curve gently back toward the rider, offering a natural grip and comfortable upright position. Racing handlebars are "dropped", offering the cyclist either an aerodynamic "hunched" position or a more upright posture in which the hands grip the brake lever mounts. Mountain bikes feature a crosswise handlebar which helps prevent the rider from pitching over the front in case of sudden deceleration. Seats also vary depending on rider preference, from the cushioned saddles favored by short-distance riders to narrower seats which allow more free leg swings.

Main article: Bicycle brake systems

Bicycle brakes are either rim brakes, in which friction pads are compressed against the wheel rims, or internal hub brakes, in which the friction pads are contained within the wheel hubs. A rear hub brake may be either hand-operated or pedal-actuated, as in the back pedal coaster brakes which were the rule in North America until the 1960s. Hub brakes do not cope well with extended braking, so rim brakes are favoured in hilly terrain. With hand-operated brakes, force is applied to brake handles mounted on the handle bars and then transmitted via Bowden cables to the friction pads. In the late 1990s, disc brakes appeared on some off-road bicycles and on tandems, but are considered impractical on road bicycles, which rarely encounter conditions where the advantages of discs are significant.

File:Utility bicycle.jpg
Dutch utility bicycle featuring basket, chainguard and mudguards, kickstand for parking, and permanently attached dynamo-powered lamps

Utility bicycles have many features intended to enhance their usefulness and comfort. Chainguards and mudguards, or fenders (U.S.), protect clothes and moving parts from oil and spray. Kick stands help with parking. Front-mounted wicker or steel baskets for holding shopping and other goods are often used. Rear racks or carriers can be used to carry items such as school satchels. Parents sometimes add rear-mounted child seats and/or an auxiliary saddle fitted to the crossbar to transport children.

Historically, materials used in bicycles have followed a similar pattern as in aircraft, the goal being strength and low weight. Since the late 1930's alloy steels have been used for frame and fork tubes in higher quality machines. Celluloid found application in mudguards, and aluminum alloys are increasingly used in components such as handle bars, seat stems, and brake levers. In the 1980s aluminum alloy frames became popular, and their affordability makes them still common. More expensive carbon fibre and titanium frames are now also available.

Performance

Racing bicycles have dropped handlebars, a narrow seat, and minimal accessories.

In both biological and mechanical terms, the bicycle is extraordinarily efficient. In terms of the number of calories of energy a person must expend to travel a given distance, investigators have calculated it to be the most efficient self-powered means of transportation1. From a mechanical viewpoint, engineers studying the efficiency of the chain drive mechanism have also determined that more than 98% of the energy delivered by the rider into the pedals is transmitted to the wheels, with less than 2% sacrificed to friction2. In terms of the ratio of cargo weight a bicycle can carry to total weight, it is also a most efficient means of cargo transportation.

Typical speeds for bicycles are 16 to 32 km/h (10 to 20 mph). On a fast racing bicycle, a reasonably fit rider can ride at 50 km/h (30 mph) on flat ground for short periods. The highest speed ever attained on the flat, without using motor pacing and wind-blocks, is by Canadian Sam Whittingham, who in 2001 set a 142.51 km/h (80.55 mph) record on his highly aerodynamic recumbent bicycle. This stands as the record for all human-powered vehicles.

Bicycle physics

A rider stays upright on a bicycle by steering the bicycle so that the point where the wheels touch the ground stays underneath the center of gravity. Once underway, this effort is largely replaced by physical forces generated by the rotation of the wheels which produce a remarkable "self-steering" effect3. The angular momentum of the wheels and the torque applied to them by the ground generates a phenomenon called precession, by which the wheel turns, or trails, toward whichever side to which the bicycle tilts. Like the rider's steering adjustments, this motion automatically returns the contact point of the wheel directly under the center of gravity. These forces, perhaps aided at very high speeds by the gyroscopic effect of the spinning wheels4, are sufficiently strong that a riderless bicycle going down a slope will stay upright by itself. Conversely, a bicycle whose steering fork is locked in a perfectly straight ahead position is virtually impossible to balance.

Accessories and repairs

Accessories are numerous, and include, lights, pump, lock, and additional (pedal or wheel-mounted) reflectors. Technical accessories include solid-state speedometers and odometers for measuring distance. Toe-clips help to keep the foot planted firmly on the pedals, and enable the cyclist to pull as well as push the pedals. Some accessories show a cultural bias. In North America, a large minority, possibly up to 25% in the US, of bicyclists wear plastic bicycle helmets for safety. In Australia and New Zealand, such helmets are required by law. In most European countries, helmets are viewed as an indicator of inexperience or recklessness, and their use is considered unusual for adult utility cyclists. The use of helmets by utility cyclists is practically unknown in most other regions.

Many cyclists also carry tool kits, containing at least a patch kit for tires and some wrenches. At one time it was possible to use a single tool to carry out most common bicycle repairs. More specialised parts now often require more complex tools, including proprietary tools specific for a given manufacturer. Some bicycle parts, particularly hub-based gearing systems, are complex, and many people prefer to leave most maintenance and repairs to professionals. Others maintain their own bicycles, finding it enhances their enjoyment of the hobby of cycling.

For more information on the technical aspects of bicycles, see also:

Social and historical aspects

Economic and social implications

Bicycle manufacturing proved to be a training ground for other industries. Building modern bicycle frames led to the development of advanced metalworking techniques, both for the frames themselves and for special components such as ball bearings, washers, and sprockets. These techniques later enabled skilled metalworkers and mechanics to develop the components used in early automobiles and aircraft. J. K. Starley's company became the Rover Cycle Company Ltd. in the late 1890s, and then the Rover auto maker. The Morris Motor Company and Skoda also began in the bicycle business, as did Henry Ford and the Wright Brothers.

In the Netherlands, bicycles are made available for use in national parks

The evolution of the bicycle had less tangible effects as well, extending early to areas as diverse as fashion and politics. In the 1890s the cycling craze led to a new set of fashions, including bloomers, which helped liberate women from corsets and other restrictive clothing. A British perfumer marketed Cycling Bouquet, which came in a tiny vial designed to fit into a lady cyclist's purse. The diamond-frame safety bicycle gave women unprecedented mobility, contributing to their emancipation in Western nations. Sociologists suggest that bicycles enlarged the gene pool for rural workers, by enabling them to easily reach the next town and increase their courting radius. In cities, bicycles helped reduce crowding in inner-city tenements by allowing workers to commute from single-family dwellings in the suburbs. They also reduced dependence on horses, and allowed people to travel into the country, since bicycles were three times as energy efficient as walking, and three to four times as fast. In North America, the political organization of bicycle enthusiasts, in such groups as the League of American Wheelmen, led to further changes. Both their model for political organization and the paved roads for which they argued facilitated the growth of the bicycle's rival, the automobile.

In recent years, US and European bicycle makers have moved much of their production to Asia. Some sixty percent of the world's bicycles are now being made in China. Despite this shift in production, as nations such as China and India become more wealthy, their own use of bicycles has declined. One of the major reasons for the proliferation of Chinese-made bicycles in foreign markets is the increasing affordability of cars and motorcycles for its own citizens 5.

Bicycles at work

Police officer on a bicycle. Image courtesy of USAID

The postal services of many countries have long relied on bicycles. The Royal Mail first started using bicycles in 1880. Bicycle delivery fleets include 37,000 in the UK, 25,700 in Germany and 10,500 in Hungary. Police officers adopted the bicycle as well, initially using their own. However they eventually became a standard issue particularly for police in rural areas. The Kent police purchased 20 bicycles in 1896, and by 1904 there were 129 police bicycle patrols operating. Some countries retained the police bicycle while others dispensed with them for a time. Bicycle patrols are now enjoying a resurgence in many cities, as traffic congestion has limited mobility for car-borne officers.

Bicycles have enjoyed substantial use as general delivery vehicles in many cities. In the UK, this use persisted for some purposes with generations of teenagers getting their first jobs delivering newspapers by bicycle. In India, many of Mumbai's Dabbawallas use bicycles to deliver hot lunches to the city’s workers. In Bogota, Colombia the city’s largest bakery recently replaced most of its delivery trucks with bicycles. Even the car industry uses bicycles. At the huge Mercedes-Benz factory in Sindelfingen, Germany workers use bicycles, colour-coded by department, to move around the factory.

Bicycles and war

Main article: Bicycles in warfare.

The bicycle is not suited for combat, but it has been used as a method of transporting soldiers and supplies to combat zones. Bicycles were used in the Boer War, where both sides used them for scouting. In World War I, France and Germany used bicycles to move troops. In its 1937 invasion of China, Japan employed some 50,000 bicycle troops, and similar forces were instrumental in Japan's march through Malaya in World War II. Germany used bicycles again in World War II, while the British employed airborne Cycle-commandos with folding bikes.

In the Vietnam War, communist forces used bicycles extensively as cargo carriers along the Ho Chi Minh Trail. There are reports of mountain bicycles being used in scouting by U.S. Special Forces in the U.S. invasion of Afghanistan and in subsequent battles against the Taliban. The only country to recently maintain a regiment of bicycle troops was Switzerland, who disbanded the last unit in 2003.

Cyclists and motorists make different demands on road design which may be lead to conflicts both in politics and on the streets. Some jurisdictions give priority to motorised traffic, for example setting up extensive one-way street systems, free-right turns, high capacity roundabouts, and slip roads. Other cities may apply active traffic restraint measures to limit the impact of motorised transport. In the former cases, cycling has tended to decline while in the latter it has tended to be maintained. Occasionally, extreme measures against cycling may occur. In Shanghai, a city where bicycles were once the dominant mode of transportation, bicycle travel on city roads was actually banned temporarily in December 2003.

In areas in which cycling is popular and encouraged, cycle-parking facilities using bicycle racks, lockable mini-garages, and patrolled cycle parks are used to reduce theft. Local governments also promote cycling by permitting the carriage of bicycles on public transport or by providing external attachment devices on public transport vehicles. Conversely, an absence of secure cycle-parking is a recurring complaint by cyclists from cities with low modal share of cycling.

Extensive bicycle path systems may be found in some cities. Such dedicated paths often have to be shared with inline skaters, scooters, skateboarders, and pedestrians. Segregating bicycle and automobile traffic in cities has met with mixed success, both in terms of safety and bicycle promotion. At some point the two streams of traffic inevitably intersect, often in a haphazard and congested fashion. Studies have demonstrated that, due to the high incidence of accidents at these sites, such segregated schemes can actually increase the number of car-bike collisions7.

Bicycle activism

Cyclists of many types form associations, both for specific interests (trails development, road maintenance, urban design, racing clubs, touring clubs, etc.) and for more global goals (energy conservation, pollution reduction, promotion of fitness). In English speaking countries, but also elsewhere, there tend to two broad factions associated with bicycle activism. One faction tends to be more overtly political and frequently has roots in the Environmental movement while the other faction tends to draw on the traditions of the established bicycle lobby. The trend has been for groups associated with the environmental movement to focus their activism on seeking the construction of segregated cycle facilities. In contrast, activists from the more established tradition tend to view such devices with suspicion and favour a more holistic approach based on planning, road design, road user education and enforcement of the existing traffic regulations. The opposition to segregated cycle facilities has well-founded historical roots regarding the safety, practicality and intent of such systems. However in some cases this opposition has a more ideological basis, some members of the US Vehicular Cycling Movement oppose the use of segregated cycling facilities as a matter of principle.

Critical Mass is a worldwide activist movement of mass bicycle protest rides that may have more overt political overtones. A recent focus, especially for European bicycle activists, has been the perceived threat of compulsory bicycle helmet legislation. Their concerns have been raised by evidence suggesting that compulsory helmet laws and helmet promotion have been associated with significant reductions in bicycle use and with simultaneous increases in the risk of injury and/or death for cyclists. As a consequence, activists from both sides have put aside their differences in order to fight the helmet lobby.

Types of bicycle

A modern touring bicycle, with accessories and baggage

By function, the four major groups of bicycles are:

  • Mountain bicycles, designed for off-road cycling, must combine relatively light weight with durability, and feature wide-gauge treaded tires, cross-wise handlebars to help the rider resist sudden jolts, and sometimes coiled-spring suspension systems.
  • Racing bicycles have lightweight frames with minimal accessories, dropped handlebars to allow for an aerodynamic riding position, and derailleur gears offering a wide variety of speeds.
  • Touring bicycles are more durable and comfortable, capable of transporting baggage, and may feature any type of gearing system.
  • Utility bicycles, designed for commuting, shopping and running errands, are the norm in Europe, and employ middle or light weight frames and tires, dependable internal hub gears, and a variety of helpful accessories.

By number of riders:

  • A tandem or twin has two riders.
  • A triplet has three riders; a quadruplet has four.
  • The largest multi-bike had 40 riders.

In all these types the riders ride one behind the other.

By general construction:

  • A penny-farthing or ordinary has one high wheel directly driven by the pedals and one small wheel.
  • On an upright bicycle the rider sits astride the saddle.
  • On a recumbent bicycle the rider reclines or lies supine.
  • A Pedersen bicycle has a bridge truss frame.
  • A folding bicycle can be quickly folded for easy carrying, for example on public transport.
  • A Moulton bicycle has a traditional seating position, and utilises small diameter, high pressure tyres and front and rear suspension.
  • An exercise bicycle doesn't go anywhere at all.

By gearing:

  • Internal hub gearing is still most common in European bicycles, usually ranging from three-speed bicycles to five and seven speed options.
  • derailleur gears, featured on most racing and touring bicycles, offering from 5 to 27 speeds
  • Fixed gear bicycles have only one gear and no freewheel mechanism, so whenever the bike is in motion the pedals continue to spin. These bikes are mainly used in track cycling or by bicycle messengers
  • Single speed bicycles have only one gear and have a freewheel mechanism.

By sport:

  • Track bicycles are ultra-simple, light bikes with but one speed which are designed for track cycling on purpose-built cycle tracks, often in velodromes.
  • Cyclo-cross bicycles are lightweight enough to be carried over obstacles, and robust enough to be cycled through mud.
  • Down-hill racers are similar to mountain bikes but have long travel suspension.
  • BMX bicycles have small wheels and are used for bicycle motocross racing, as well as for wheelies, jumps, and other acrobatics.

By means of propulsion:

  • A pedal cycle is driven by pedals.
  • A hand-cranked bicycle is driven by a hand crank.
  • An electric bicycle assists the rider with an electric motor.
  • A moped propels the rider with a motor, but includes bicycle pedals for human propulsion.
  • Shaft drive bicycles connect the pedals to the rear hub with a shaft instead of a chain.

Other types:

  • Road bicycle is a generic term which may refer to a bicycle with both racing and touring features
  • Hybrid bicycles are a compromise between the mountain and racing style bicycles which replaced European-style utility bikes in North America in the early 1970s. They have a light frame, medium gauge wheels, and derailleur gearing, and feature straight or curved-back, touring handle bars for more upright riding.
  • Cruisers are designed for comfort, with curved back handlebars, padded seats, and balloon tires. Cruisers typically have minimal gearing and are often available for rental at beaches and parks which feature flat terrain.
  • Freight bicycles are designed for transporting large or heavy loads.
  • Velotaxis, pedicabs and trishaws are used to transport taxi passengers.
  • Velomobiles provide all-weather pedal-powered transportation.

See also

Notes

  • 1 Scientific American, March 1973: "Bicycle Technology", by S.S.Wilson.
  • 2 "Johns Hopkins Gazette", Aug.30, 1999
  • 3 "The Stability of the Bicycle", David Jones, "Physics Today", April 1970: pp.34-40
  • 4 Townsend (external link, below)
  • 5 The Economist, Feb.15, 2003
  • 6 "Cities for Cyclists" (external link, below)
  • 7 "Bicycling Life" (external link, below)
  • 8 "John Forester's Effective Cycling" (external link, below)


References

  • All About Bicycling, Rand McNally.
  • Dick Teresi, Popular mechanics book of bikes and bicycling, Hearst Corp, 1975.
  • The New Columbia Encyclopedia
  • Richard Ballantine, Richard's Bicycle Book, Pan, 1975.
  • Roni Sarig, The Everything Bicycle Book, Adams Media Corporation, 1997
  • David B. Perry, Bike Cult: the Ultimate Guide to Human-powered Vehicles, Four Walls Eight Windows, 1995.
  • Caunter C. F. The History and Development of Cycles Science Museum London 1972.

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