   #copyright

Bicycle

2007 Schools Wikipedia Selection. Related subjects: Road transport

   This racing bicycle is built using lightweight, shaped aluminium tubing
   and carbon fiber stays and forks. It sports a drop handlebar and thin
   tires and wheels for efficiency and aerodynamics.
   Enlarge
   This racing bicycle is built using lightweight, shaped aluminium tubing
   and carbon fibre stays and forks. It sports a drop handlebar and thin
   tires and wheels for efficiency and aerodynamics.
   This mountain bicycle features oversized tires, a sturdy frame, front
   shock absorbers, and handlebars oriented perpendicular to the bike's
   axis
   Enlarge
   This mountain bicycle features oversized tires, a sturdy frame, front
   shock absorbers, and handlebars oriented perpendicular to the bike's
   axis

   A bicycle, or bike, is 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.

   First introduced in 19th-century Europe, bicycles now number over one
   billion worldwide, providing the principal means of transportation in
   many regions, notably China and the Netherlands. They are also a
   popular form of recreation, and have been adapted for use in many other
   fields of human activity, including children's toys, adult fitness,
   military and local police applications, courier services, and cycle
   sports.

   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.

   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 both old and newer areas.

History

   A smartly dressed couple seated on an 1886 "quadricycle" for two
   Enlarge
   A smartly dressed couple seated on an 1886 " quadricycle" for two

   Several inventors and innovators contributed to the development of the
   bicycle. Its earliest known forebears were called velocipedes, and
   included many types of human-powered vehicles. One of these, the
   scooter-like dandy horse of the French Comte de Sivrac, dating to 1790,
   was long cited as the earliest bicycle. Most bicycle historians now
   believe that these hobbyhorses with no steering mechanism probably
   never existed, but were made up by Louis Baudry de Saunier, a
   19th-century French bicycle historian. However, the term hobbyhorse was
   later applied to the first documented ancestor of the modern bicycle,
   first introduced to the public in Paris by the German Baron Karl Drais
   in 1818..

   The ancestor of the bicycle was first created by a German Baron, Karl
   Drais, who invented and patented his machine in 1817. So the first
   bicycle ride was from his residence town Mannheim to the suburb
   Rheinau. A number of these draisines or dandy horses still exist,
   including one at the Paleis het Loo museum in Apeldoorn, the
   Netherlands. These were pushbikes, powered by the action of the rider's
   feet pushing against the ground. The Draisienne had two in-line wheels
   connected by a wooden frame. The rider sat astride and pushed it along
   with his feet, while steering the front wheel.

   Scottish blacksmith Kirkpatrick MacMillan refined this in 1839 by
   adding a mechanical crank drive to the rear wheel, thus creating the
   first true "bicycle" in the modern sense. His system employed a pair of
   treadle drives connected by rods to a rear wheel crank, rather like a
   steam locomotive's driveshaft. Although the design was copied by at
   least two other Scottish builders, it was overtaken in popularity and
   influence by an inferior one.

   In the 1850s and 1860s, Frenchmen Ernest Michaux and Pierre Lallement
   took bicycle design in a different direction, placing the pedals on an
   enlarged front wheel. Their creation, which came to be called the
   "Boneshaker", featured a heavy steel frame on which they mounted wooden
   wheels with iron tires. Lallement emigrated to the United States, where
   he recorded a patent on his bicycle in 1866 in New Haven, Connecticut.
   The Boneshaker was further refined by Englishman James Starley in the
   1870s. 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. With tires of solid rubber, his
   machine became known as the ordinary. British cyclists likened the
   disparity in size of the two wheels to their coinage, nicknaming it the
   penny-farthing. The primitive bicycles of this generation were
   difficult to ride, and the high seat and poor weight distribution made
   for dangerous falls.
   Bicycle in Victorian Plymouth, with a predecessor of the Starley
   diamond-frame
   Enlarge
   Bicycle in Victorian Plymouth, with a predecessor of the Starley
   diamond-frame

   The subsequent dwarf ordinary addressed some of these faults by adding
   gearing, reducing the front wheel diameter, and setting the seat
   further back, with no loss of speed. 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 the chain
   and producing rear-wheel drive. These models were known as dwarf
   safeties, or safety bicycles, for their lower seat height and better
   weight distribution. Starley's 1885 Rover is usually described as the
   first recognizably modern bicycle. Soon, the seat tube was added,
   creating the double-triangle, diamond frame of the modern bike.

   While the Starley design was much safer, the return to smaller wheels
   made for a bumpy ride. The next 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.
   Soon after, 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 only slowly 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 extremely popular.
   American bike from 1896. The frame is made of bamboo
   Enlarge
   American bike from 1896. The frame is made of bamboo
   A more-than-typical Amsterdam 'granny bike'
   Enlarge
   A more-than-typical Amsterdam 'granny bike'
   Plastic bicycle from the 80's
   Enlarge
   Plastic bicycle from the 80's

   Successful early bicycle manufacturers included Englishman Frank Bowden
   and German builder Ignaz Schwinn. Bowden started the Raleigh company in
   Nottingham in the 1890s, and was soon producing some 30,000 bicycles a
   year. Schwinn emigrated to the United States, where he founded his
   similarly successful company in Chicago in 1895. Schwinn bicycles soon
   featured widened tires and spring-cushioned, padded seats, sacrificing
   a certain amount of efficiency for increased comfort. Facilitated by
   connections between European nations and their overseas colonies,
   European-style bicycles were soon available worldwide. 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 levelled off or declined
   as motorized transportation became affordable and car-centred policies
   led to an increasingly hostile 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. However, in other parts of the world, such as China,
   India, and European countries such as Germany, Denmark, and the
   Netherlands, the traditional utility bicycle remained a mainstay of
   transportation; its design changed only gradually to incorporate
   hand-operated brakes, with internal hub gears allowing up to seven
   speeds. In the Netherlands, such so-called 'granny bikes' have remained
   popular, and are again in production. In the early 1980s, Swedish
   company Itera invented a new type of bicycle, called the Itera plastic
   bicycle, made entirely out of plastics. The plastic bicycle was however
   a commercial failure.

   In North America, increasing consciousness of physical fitness and
   environmental preservation spawned a renaissance of bicycling in the
   late 1960s. Bicycle sales in the US boomed, largely in the form of the
   racing bicycles, long used in such events as the hugely popular Tour de
   France. Sales were also helped by a number of technical innovations
   that were new to the US market, including higher performance steel
   alloys and gearsets with an increasing number of gears. While 10-speeds
   were very popular in the 1970s, 12-speed designs were introduced in the
   1980s, and today most bikes feature 18 or more speeds. By the 1980s,
   these newer designs had driven the three-speed bicycle from the roads.
   In the late 1980s, the mountain bike became particularly popular, and
   in the 1990s something of a major fad. These task-specific designs led
   many American recreational cyclists to demand a more comfortable and
   practical product. Manufacturers responded with the hybrid bicycle,
   which restored many of the features long enjoyed by riders of the
   time-tested European utility bikes.

Technical aspects

   Reflectors for night riding are one of many available safety
   accessories
   Reflectors for night riding are one of many available safety
   accessories

Legal requirements

   The 1968 Vienna Convention on Road Traffic considers a bicycle to be a
   vehicle, and a person controlling a bicycle is considered a driver. The
   traffic codes of many countries reflect these definitions and demand
   that a bicycle satisfy certain legal requirements, sometimes even
   including licensing, before it can be used on public roads. In many
   jurisdictions it is an offense to use a bicycle that is not in
   roadworthy condition. In most places, bicycles must have functioning
   front and rear lights or lamps when ridden after dark. 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

Frame

   Nearly all modern upright bicycles feature the diamond frame, a truss,
   consisting of two triangles: the front triangle and the rear triangle.
   The front triangle consists of the head tube, top tube, down tube and
   seat tube. The head tube contains the headset, the set of bearings that
   allows the fork to spin smoothly. The top tube connects the head tube
   to the seat tube at the top, and the down tube connects the head tube
   to the bottom bracket. The rear triangle consists of the seat tube and
   paired chain stays and seat stays. The chain stays run parallel to the
   chain, connecting the bottom bracket to the rear dropouts. The seat
   stays connect the top of the seat tube at or near the same point as the
   top tube) to the rear dropouts.
   Bike on the beach in Goa, India
   Enlarge
   Bike on the beach in Goa, India

   Historically, women's bicycle frames had a top tube that connected in
   the middle of the seat tube instead of the top, resulting in a lower
   standover height at the expense of compromised structural integrity,
   since this places a strong bending load in the seat tube, and bicycle
   frame members are typically weak in bending. This design purportedly
   allows the rider to mount and dismount in a dignified way while wearing
   a skirt or dress, although this is difficult on a properly-sized
   diamond frame. While some women's bicycles continue to use this frame
   style, there is also a hybrid form, the mixte or step-through frame,
   which splits the top tube into two small top tubes that bypass the seat
   tube and connect to the rear dropouts. The ease of stepping through is
   also appreciated by those with limited flexibility or other joint
   problems. Unfortunately for the old tall man, because of its persistent
   image as a "women's" bicycle, the vast majority of mixte frames are
   quite small.

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

Drivetrain

   Shimano XT rear derailleur on a mountain bike
   Enlarge
   Shimano XT rear derailleur on a mountain bike

   The drivetrain begins with pedals which rotate the cranks, which fit
   into the bottom bracket. Attached to the right crank is the chainring
   or sprocket which drives the chain, which in turn rotates the rear
   wheel via the rear sprockets, or cassette. Various gearing systems,
   described below, may be interspersed between the pedals and rear wheel;
   these gearing systems vary the number of rear wheel revolutions
   produced by each turn of the pedals.

   Since cyclists' legs produce a limited amount of power most efficiently
   over a narrow range of cadences, a variable gear ratio is needed to
   maintain an optimum pedaling speed while covering varied terrain. The
   gear systems are usually 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. Rear hub gears may offer 2, 3, 4, 5, 6, 7, 8, 9, 12, or
       14 speeds. Bottom bracket fittings offer a choice of 2 speeds, and
       are generally foot-operated.
     * External gearing utilizes derailleurs, which can be placed on both
       the front chainring and on the rear cluster or cassette, to push
       the chain to either side, derailing it from the sprockets. The
       sides of the gear rings catch the chain, pulling it up onto their
       teeth to change gears. There may be 1 to 3 chainrings, and 5 to 10
       sprockets on the cassette.

   Internal hub gears are immune to adverse weather conditions that affect
   derailleurs, and often last longer and require less maintenance.
   However, they may be heavier and/or more expensive, and often do not
   offer the same range or number of gears. Internal hub gearing still
   predominates in some regions, particularly on utility bikes, whereas in
   other regions, such as the USA, external derailleur systems
   predominate.
   Bicycles in the Netherlands
   Enlarge
   Bicycles in the Netherlands

   Road bicycles have close set multi-step gearing, which allows very fine
   control of cadence, while utility cycles offer fewer, more widely
   spaced speeds. Mountain bikes and most entry-level road racing bikes
   may offer an extremely low gear to facilitate climbing slowly on steep
   hills.

   Fixed-gear track racing bikes can achieve transmission efficiencies of
   over 99% (nearly all the energy put in at the pedals ends up at the
   wheel). Biomechanical factors however determine that a human can
   deliver maximum power only over a narrow range of crank rotational
   speed or cadence. To match the power source with the load under varying
   conditions, a variable gear ratio is needed, and they work very well,
   though at the expense of mechanical efficiency. The efficiency varies
   considerably with the gear ratio being used. In a typical hub gear
   mechanism the mechanical efficiency will be between 82% and 92%
   depending on the ratio selected. Which ratios are best and worst
   depends on the specific model of hub gear. Derailleur type mechanisms
   fare better, with a typical mid-range product (of the sort used by
   serious amateurs) achieving between 88% and 99% efficiency at 100W. In
   derailleur mechanisms the highest efficiency is achieved by the larger
   cogs. Efficiency generally decreases with smaller cog and chainwheel
   sizes. Derailleur efficiency is also compromised with cross-chaining,
   or running large-ring to large-cog or small-ring to small-cog. This
   also results in increased wear because of the lateral deflection of the
   chain.

   There have been, and still are, drivetrains that are quite different
   from these:
     * Retro-Direct drivetrains used on some early 20th century bicycles
       have been resurrected by bicycle hobbyists. These have two gears
       but no gear lever; the operator simply pedals forward for one gear
       and backward for the other.
     * Other bicycles of that era dispensed with the chain entirely and
       used an enclosed driveshaft and bevel gears. These shaft-driven
       bicycle were strongly built but were not mechanically efficient.
       They were primarily marketed to women, as the enclosed gears would
       not entangle clothing. In recent years, a small number of
       shaft-drive systems have reappeared on the market as a specialty
       item .
     * In recent years, Steve Christini and Mike Dunn added a two-wheel
       drive option to bicyclists. Their AWD system, aimed at mountain
       bikers, comprises an adapted differential that sends power to the
       front wheel once the rear begins to slip.

Steering and seating

   The handlebars turn the fork and the front wheel via the stem, which
   articulates with the headset. Three styles of handlebar are common.
   Upright handlebars, the norm in Europe and elsewhere until the 1970s,
   curve gently back toward the rider, offering a natural grip and
   comfortable upright position. Drop handlebars are "dropped", offering
   the cyclist either an aerodynamic "crouched" position or a more upright
   posture in which the hands grip the brake lever mounts. Mountain bikes
   feature a straight handlebar, which helps prevent the rider from
   pitching over the front in case of sudden deceleration.

   Variations on these styles exist. Bullhorn style handlebars are often
   seen on modern time trial bicycles, equipped with two forward-facing
   extensions, allowing a rider to rest the entire forearm on the bar.
   These are usually used in conjunction with the aero bar, a pair of
   forward-facing extensions spaced close together, to promote better
   aerodynamics. The Bullhorn was banned from ordinary road racing because
   it is difficult for the rider to control in bike traffic.

   Saddles also vary with rider preference, from the cushioned ones
   favoured by short-distance riders to narrower saddles which allow more
   free leg swings. Comfort depends on riding position. With comfort bikes
   and hybrids the cyclist sits high over the seat, their weight directed
   down onto the saddle, such that a wider and more cushioned saddle is
   preferable. For racing bikes where the rider is bent over, weight is
   more evenly distributed between the handlebars and saddle, and the hips
   are flexed, and a narrower and harder saddle is more efficient.

   A recumbent bicycle has a reclined chair-like seat that is more
   comfortable than a saddle, especially for riders who suffer from
   certain types of back pain.

Brakes

   Traditional L-shaped cantilever brake
   Enlarge
   Traditional L-shaped cantilever brake

   Modern bicycle brakes are either rim brakes, in which friction pads are
   compressed against the wheel rims, internal hub brakes, in which the
   friction pads are contained within the wheel hubs, or disc brakes. 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 drum 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, tandems and recumbent
   bicycles, but are considered impractical on road bicycles, which rarely
   encounter conditions where the advantages of discs are significant.

   The advantages of discs make them well-suited to steep, extended
   downhills through wet and muddy off-road terrain, which falls under the
   category of downhill and freeride bicycle riding. The use of tires as
   large as 3.0 inches in width also makes disc brakes a necessity, as rim
   brakes simply cannot straddle a tire that wide.

   Two main disc brake systems exist: hydraulic and mechanical
   (cable-actuated). Mechanical disc brakes have less modulation than
   hydraulic disc brake systems, and since the cable is usually open to
   the outside, mechanical disc brakes tend to pick up small bits of dirt
   and grit in the cable lines when ridden in harsh terrain. Hydraulic
   disc brake systems generally keep contaminants out better. However,
   since hydraulic disc brakes usually require relatively specialized
   tools to bleed the brake systems, repairs on the trail are difficult to
   perform, whereas mechanical disc brakes rarely fail. Also, the
   hydraulic fluid may boil on steep, continuous downhills. This is due to
   heat building up in the disc and pads and can cause the brake to lose
   its ability to transmit force through incompressible fluids, since some
   of it has become a gas, which is compressible. To avoid this problem,
   203 mm (8 inch) diameter disc rotors have become common on downhill
   bikes. Larger rotors dissipate heat more quickly and have a larger
   amount of mass to absorb heat. For these reasons, one must weigh the
   advantages and disadvantages of using a hydraulic system versus a
   mechanical system.

   For track cycling, track bicycles do not have brakes. Most track bike
   frames and forks do not have holes for mounting brakes, although with
   their increasing popularity among some road cyclists, some
   manufacturers have drilled their track frames to enable the fitting of
   brakes. Brakes are not required for riding on a track because all
   riders ride in the same direction and there are no corners or other
   traffic. Track rider are still able to slow down because all track
   bicycles are fixed, meaning that there is no freewheel. Without a
   freewheel, coasting is impossible, so when the rear wheel is moving,
   the crank is moving. To slow down one may apply resistance to the
   pedals. Cyclists who ride a track bike without brake(s) on the road can
   also slow down by skidding, by unweighting the rear wheel and applying
   a backwards force to the pedals, causing the rear wheel to lock up and
   slide along the road.

Accessories and Repairs

   Some components, which are often optional accessories on sports
   bicycles, are standard features on utility bicycles to enhance their
   usefulness and comfort. Chainguards and mudguards, or fenders, protect
   clothes and moving parts from oil and spray. Kick stands help with
   parking. Front-mounted wicker or steel baskets for carrying 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.
   Touring bicycle equipped with head lamp, pump, rear rack,
   fenders/mud-guards, and numerous saddle-bags.
   Enlarge
   Touring bicycle equipped with head lamp, pump, rear rack,
   fenders/mud-guards, and numerous saddle-bags.

   Toe-clips and toestraps, or clipless pedals, help to keep the foot
   planted firmly on the pedals, and enable the cyclist to pull as well as
   push the pedals. Technical accessories include solid-state speedometers
   and odometers for measuring distance. Other accessories include lights,
   reflectors, tire pump, security lock, mirror, and horn. A bicycle
   helmet is classified by some as an accessory, but as an item of
   clothing by others.

   Many cyclists carry tool kits, containing at least a tire patch kit
   (and/or a spare tube), tire levers, and allen wrenches. A single tool
   once sufficed for most repairs. More specialised parts now require more
   complex tools, including proprietary tools specific for a given
   manufacturer. Some bicycle parts, particularly hub-based gearing
   systems, are complex, and many prefer to leave maintenance and repairs
   to professionals. Others maintain their own bicycles, enhancing their
   enjoyment of the hobby of cycling.

   It is also possible to purchase road-side assistance from companys such
   as the Better World Club.

Performance

   In both biological and mechanical terms, the bicycle is extraordinarily
   efficient. In terms of the amount of energy a person must expend to
   travel a given distance, investigators have calculated it to be the
   most efficient self-powered means of transportation. From a mechanical
   viewpoint, up to 99% of the energy delivered by the rider into the
   pedals is transmitted to the wheels, although the use of gearing
   mechanisms may reduce this by 10-15%. 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.

   A human being travelling on a bicycle at low to medium speeds of around
   10-15 mph (16-24 km/h), using only the energy required to walk, is the
   most energy-efficient means of transport generally available. Air drag,
   which increases with the square of speed, requires increasingly higher
   power outputs relative to speed. A bicycle which places the rider in a
   seated position, supine position or, more rarely, prone position, and
   which may be covered in an aerodynamic fairing to achieve very low air
   drag, is referred to as a recumbent bicycle or human powered vehicle.
   Humans create the greatest amount of drag on an upright bicycle at
   about 75% of the total drag.

Dynamics

   A bicycle stays upright by being steered so as to keep its centre of
   gravity over its wheels. This steering is usually provided by the
   rider, but under certain conditions may be provided by the bicycle
   itself.

   A bicycle must lean in order to turn. This lean is induced by a method
   known as countersteering, which can be performed by the rider turning
   the handlebars directly with the hands or indirectly by leaning the
   bicycle.

   Short-wheelbase or tall bicycles, when braking, can generate enough
   stopping force at the front wheel in order to flip longitudinally. This
   action, especially if performed on purpose, is known as a stoppie or
   front wheelie.

Social and historical aspects

   Present day: Bikes still popular in Amsterdam
   Enlarge
   Present day: Bikes still popular in Amsterdam

Economic implications

   Bicycle manufacturing proved to be a training ground for other
   industries and 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 aircrafts. 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 (in Oxford) and Škoda also began in the
   bicycle business, as did Henry Ford and the Wright Brothers.

   Some bicycle clubs and national associations became prominent advocates
   for improvements to roads and highways. In the United States, the
   League of American Wheelmen lobbied for the improvement of roads in the
   last part of the 19th century, founding and leading the national Good
   Roads Movement. Both their model for political organization and the
   paved roads for which they argued facilitated the growth of the
   bicycle's rival, the automobile.

   Until recently cycle manufacturers in the west generally built their
   own frames and used components made by other companies to assemble a
   complete cycle, although very large companies such as Raleigh used to
   make almost every part of a bicycles including eg bottom bracket axles
   etc. In recent years, US and European bicycle makers have changed their
   methods of production. Many companies now only assemble, every part of
   the bicycle including the frame will have been made by other companies.
   Many newer or smaller companies do no manufacturing or even assembly at
   all, they only deal with design and marketing, actual manufacturing is
   done by other companies. 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 due to the increasing affordability of cars and
   motorcycles. One of the major reasons for the proliferation of
   Chinese-made bicycles in foreign markets is the lower cost of labour in
   China.

Female emancipation

   Woman with bicycle, 1890s
   Enlarge
   Woman with bicycle, 1890s

   The diamond-frame safety bicycle gave women unprecedented mobility,
   contributing to their emancipation in Western nations. As bicycles
   became safer and cheaper, more women had access to the personal freedom
   they embodied, and so the bicycle came to symbolise the New Woman of
   the late nineteenth century, especially in Britain and the United
   States.

   The bicycle was recognised by nineteenth-century feminists and
   suffragists as a "freedom machine" for women. American Susan B. Anthony
   said in a New York World interview on February 2, 1896: "Let me tell
   you what I think of bicycling. I think it has done more to emancipate
   women than anything else in the world. It gives women a feeling of
   freedom and self-reliance. I stand and rejoice every time I see a woman
   ride by on a wheel...the picture of free, untrammeled womanhood." In
   1895 Frances Willard, the tightly-laced president of the Women’s
   Christian Temperance Union, wrote a book called How I Learned to Ride
   the Bicycle, in which she praised the bicycle she learned to ride late
   in life, and which she named "Gladys", for its "gladdening effect" on
   her health and political optimism. Willard used a cycling metaphor to
   urge other suffragists to action, proclaiming, "I would not waste my
   life in friction when it could be turned into momentum."

   The male anger at the freedom symbolised by the New (bicycling) Woman
   was demonstrated when the male undergraduates of Cambridge University
   chose to show their opposition to the admission of women as full
   members of the university by hanging a woman in effigy in the main town
   square -- tellingly, a woman on a bicycle. This was as late as 1897.

   In the 1890s the bicycle craze led to a movement for so-called rational
   dress, which helped liberate women from corsets and ankle-length skirts
   and other restrictive garments, substituting the then-shocking
   bloomers.

Other social implications

   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 more spacious
   dwellings in the suburbs. They also reduced dependence on horses, with
   all the knock-on effects this brought to society. Bicycles allowed
   people to travel for leisure into the country, since bicycles were
   three times as energy efficient as walking, and three to four times as
   fast.

Cycling and public health

   The physical exercise gained from cycling is generally linked with
   increased health and wellbeing. According to the World Health
   Organisation, physical inactivity is second only to tobacco smoking as
   a health risk in developed countries, and this is associated with many
   tens of billions of dollars of healthcare costs . The WHO's report
   suggests that increasing physical activity is a public health 'best
   buy', and that cycling is a 'highly suitable activity' for this
   purpose. The charity Sustrans reports that investment in cycling
   provision can give a 20:1 return from health and other benefits .

   Cycling is not generally considered as a high-risk activity . In the
   UK, casualty rates per kilometer are comparable with walking, but are
   higher than for car occupants. Most cycle deaths result from a
   collision with a car or heavy goods vehicle .

   A Danish study in 2000 concluded that cycling to work was linked to a
   40% reduction in mortality rate; this included all causes of death,
   including road deaths.

Uses for bicycles

Bicycles at work

   Police officer on a bicycle
   Enlarge
   Police officer on a bicycle

   The postal services of many countries have long relied on bicycles. The
   British Royal Mail first started using bicycles in 1880; now bicycle
   delivery fleets include 37,000 in the UK, 25,700 in Germany, 10,500 in
   Hungary and 7000 in Sweden. The London Ambulance Service has recently
   introduced bicycling paramedics, who can often get to the scene of an
   incident in Central London more quickly than a motorised ambulance.

   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 the mobility of car-borne officers is becoming increasingly
   limited by traffic congestion and pedestrianisation. They also have the
   advantages that the officers are inherently more open to the public,
   and the transport is quieter to permit a more stealthy approach toward
   suspects. The pursuit of suspects can also be assisted by a bicycle.
   A bicycle loaded with tender coconut for sale. Karnataka, India
   Enlarge
   A bicycle loaded with tender coconut for sale. Karnataka, India

   Bicycles enjoy substantial use as general delivery vehicles in many
   countries. In the UK and North America, generations of teenagers have
   got their first jobs delivering newspapers by bicycle. London has many
   delivery companies that use bicycles with trailers. Most cities in the
   West, and many outside it, support a sizable and visible industry of
   cycle couriers who deliver documents and small packages. In India, many
   of Mumbai's Dabbawalas use bicycles to deliver hot lunches to the
   city’s workers. In Bogotá, 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.

Bicycle recreation

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

   Bicycles are used for recreation at all ages. Bicycle touring, also
   known as cyclotourism, involves touring and exploration or sightseeing
   by bicycle for leisure. A brevet or randonnée is an organized
   long-distance ride.

   One aspect of Dutch popular culture is enjoying relaxed cycling in the
   countryside of the Netherlands. The land is very flat and full of
   public bicycle trails where cyclist aren't bothered by cars and other
   traffic, which makes it ideal for cycling recreation. Many Dutch people
   subscribe every year to an event called fietsvierdaagse — four days of
   organised cycling through the local environment. Paris-Brest-Paris
   (PBP), which began in 1891, is the oldest bicycling event still run on
   a regular basis on the open road, covers over 1200 km and imposes a
   90-hour time limit.

Bicycles and war

   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 Second 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 Malaysia 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.
   British troops, designated Light Bicycle Infantry LBI were recently, as
   of 06 January 2005, using bicycles to patrol in Basra, Iraq.

   The only country to recently maintain a regiment of bicycle troops was
   Switzerland, who disbanded the last unit in 2003.

Bicycle racing

   Bicycle racing around 1909
   Enlarge
   Bicycle racing around 1909

   Shortly after the introduction of bicycles, competitions developed
   independently in many parts of the world. Early races involving
   boneshaker style bicycles were predictably fraught with injuries. Large
   races became popular during the 1890's "Golden Age of Cycling", with
   events across Europe, and in the U.S. and Japan as well. At one point,
   almost every major city in the US had a velodrome or two for track
   racing events. However since the middle of the 20th Century cycling has
   become a minority sport in the US whilst in Continental Europe it
   continues to be a major sport, particularly in France, Belgium and
   Italy. The most famous of all bicycle races is the Tour de France. This
   began in 1903, and continues to capture the attention of the sporting
   world.

   As the bicycle evolved its various forms, different racing formats
   developed. Road races may involve both team and individual competition,
   and are contested in various ways. They range from the one-day road
   race, criterium, and time trial to multi-stage events like the Tour de
   France and its sister events which make up cycling's Grand Tours.
   Recumbent bicycles were banned from bike races in 1934 after Marcel
   Berthet set a new hour record in his Velodyne streamliner (49.992 km on
   18 November 1933). Track bicycles are used for track racing in
   Velodromes , while cyclo-cross races are held on rugged outdoor
   terrain. In the past decade, mountain bike racing has also reached
   international popularity and is even an Olympic sport.

   The governing body of international cycle sport, the Union Cycliste
   Internationale, decided in the late 1990s to create additional rules
   restricting the design of racing bicycles. These rules met with
   considerable controversy and to some extent arrested the development of
   the racing bicycle. Their stated motive was so that developing
   countries could compete in international competitions without requiring
   large equipment budgets, and to re-focus attention on the athlete
   rather than the bicyle. For example, monocoque frames, such as used by
   Chris Boardman to win the Gold medal in 1992 Olympic individual pursuit
   event in Barcelona, were no longer permitted.

Modal share: cycle use in modern cities

   A parking lot for bicycles in Niigata,_Niigata, Japan.
   Enlarge
   A parking lot for bicycles in Niigata,_Niigata, Japan.

   Cyclists and motorists make different demands on road design which may
   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 collisions.

Cycling activism

   Cyclists 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). Two broad themes run in bicycle
   activism: one more overtly political with roots in the environmental
   movement; the other drawing on the traditions of the established
   bicycle lobby.

   Such groups promote the bicycle as an alternative mode of transport and
   emphasize the potential for energy and resource conservation and health
   benefits gained from cycling versus automobile use. Activists in both
   camps also argue for improved local and inter-city rail services and
   other methods of mass transportation, and also for greater provision
   for cycle carriage on such services. Many cities also have community
   bicycle programs that promote cycling, especially as a means of
   inner-city transport. [[Image:Critical Mass, San Francisco, April 29,
   2005.jpg|thumb|left|300px|San Francisco Critical Mass, 29 April 2005.]]
   Controversially, some bicycle activists (including some traffic
   management advisors) seek the construction of segregated cycle
   facilities for journeys of all lengths. Other activists, especially
   those from the more established tradition, view the safety,
   practicality, and intent of many segregated cycle facilities with
   suspicion. They favour a more holistic approach based on the 4 'E's;
   education (of everyone involved), encouragement (to apply the
   education), enforcement (to protect the rights of others), and
   engineering (to facilitate travel while respecting every person's equal
   right to do so). In some cases this opposition has a more ideological
   basis: some members of the Vehicular Cycling movement oppose segregated
   public facilities, such as on-street bike lanes, on principle. Some
   groups offer training courses to help cyclists integrate themselves
   with other traffic. This is part of the ongoing cycle path debate.

   Critical Mass is a worldwide activist movement of mass bicycle protest
   rides. It incorporates the themes of increasing the road- and
   mind-share given to bicycle transport, and has drawn support from
   environmentally minded campaigners and other schools of political
   thought. According to participants in Critical Mass, "We aren't
   blocking traffic, we are traffic!" However, their particular forms of
   protest has drawn criticism from the broader streams of activism.

   Midnight Ridazz is an massive established bicycle ride in Los Angeles
   based on recreational activism. The ride incorporates themes and ride
   routes designed to maximize fun and comraderie without any overt
   political agenda that might fracture the group of diverse riders. The
   one goal of Midnight Ridazz is to have fun riding a bike and thus
   inspire others to ride and have fun as well.

   There is a long-running cycle helmet debate among activists. The most
   heated controversy surrounds the topic of compulsory helmet use.

Types of bicycle

   Bicycles can be categorized in different ways: e.g. by function, by
   number of riders, by general construction, by gearing or by means of
   propulsion. The most common types are:
   Utility bicycles parked outside an academic building at Stanford
   University
   Enlarge
   Utility bicycles parked outside an academic building at Stanford
   University
     * Utility bicycles are designed for commuting, shopping and running
       errands. They employ middle or heavy weight frames and tires,
       internal hub gearing, and a variety of helpful accessories. The
       riding position is usually upright.
     * Mountain bicycles are designed for off-road cycling, and include
       other sub-types of off-road bicycles such as Cross Country
       (i.e."XC"), Downhill , and to a lesser extent Freeride bicycles.
       All mountain bicycles feature sturdy, highly durable frames and
       wheels, wide-gauge treaded tires, and cross-wise handlebars to help
       the rider resist sudden jolts. Some mountain bicycles feature
       various types of suspension systems (e.g. coiled spring, air or gas
       shock), and hydraulic or mechanical disc brakes. Mountain bicycle
       gearing is very wide-ranging, from very low ratios to high ratios,
       typically with 21 to 30 gears.
     * Racing bicycles are designed for speed, and include road, time
       trial, and track bicycles. They have lightweight frames and
       components with minimal accessories, dropped handlebars to allow
       for an aerodynamic riding position, narrow high-pressure tires for
       minimal rolling resistance and multiple gears. Racing bicycles have
       a relatively narrow gear range, and typically varies from medium to
       very high ratios, distributed across 18, 20, 27 or 30 gears. The
       more closely spaced gear ratios allow racers to choose a gear which
       will enable them to ride at their optimum pedaling cadence for
       maximum efficiency.
     * Touring bicycles are designed for bicycle touring and long
       journeys. They are durable and comfortable, capable of transporting
       baggage, and may feature any type of gearing system.
     * Cruiser bicycles feature balloon tires, curvy "cantilever" frames,
       upright riding position, and padded saddles. They are popular
       recreation bikes for those who value style and durability over
       performance, especially in resort areas. The many elaborate and
       fanciful cruiser designs of the 1930s-1950s have become a focus for
       bicyle collectors.
     * tandems or twins have two riders, one on the front and one on the
       back.
     * folding bicycles can be quickly folded for easy carrying, for
       example on public transport.
     * unicycles are not proper bicycles, as they have only one wheel.

Standards

   A number of formal and industry standards exist for bicycle components,
   to help make spare parts exchangeable:
     * ISO 5775 Bicycle tire and rim designations
     * ISO 8090 Cycles — Terminology (same as BS 6102-4)
     * ISO 4210 Cycles — Safety requirements for bicycles

   Retrieved from " http://en.wikipedia.org/wiki/Bicycle"
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   with only minor checks and changes (see www.wikipedia.org for details
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