Shopping on line can be easy, simple and save you lots of money. It can also take a lot of your time, frustrate you, and result in unwanted purchases. Now the same can be said for regular high street shopping, but with the vast opportunity presented by the Internet it will pay you to spend a few minutes reading this and understanding how to better optimize your Bicycle shopping experience:

1. Compare - without doubt the biggest advantage that the Bicycle offers shoppers today is the ability to compare thousands of Bicycle at a time. This is a great thing, but not necessarily all the time! Too much can be daunting at times so take advantage of the great comparison sites and where possible let them do the hard work for you.

2. Research - if it has been said it will be on the internet. Ignorance is no longer a justifiable reason for buying the wrong thing. Take the time to research in detail everything that you could possible want to know about

3. Testimonials - don't know anybody that has bought a Bicycle? Wrong! If the Bicycle is good the internet will let you know. Use the Internet as a friend and get testimonials before you buy.

4. Questions - Got a question about Bicycle then search the Forums, FAQ's, Blogs etc. Don't be afraid to ask .....

5. Reputation - Never heard of the company selling Bicycle? Don't worry, no reason why you should know every company in the world, but you know someone that does! Use the internet to find out what people are saying about Bicycle and build up a picture of their reputation for sales, returns, customer service, delivery etc.

6. Returns - still worried that even after all of the above your Bicycle wont be what you want? Check out the returns policy. There is so much competition now that someone, somewhere is bound to offer the terms that you are comfortable with.

7. Feedback - happy with your Bicycle then let people know, after all you are depending on others people input in your buying decision, so why not give a little back.

8. Security - check for the yellow padlock on the Bicycle site before you buy, and the s after http:/ /i.e. https:// = a secure site

9. Contact - got a question about Bicycle, or want to leave a comment then check out the sites contact page. Reputable companies have them and respond.

10. Payment - ready to pay for your Bicycle, then use your credit card or PayPal! Be aware of companies that don't accept them, there may be genuine reasons but given the huge amount of choice you have when buying online there is no reason at all not to buy via credit card or PayPal.



is built using lightweight, shaped aluminium tubing and Graphite-reinforced plastic stays and forks. It sports a drop handlebar and thin tires and wheels for efficiency and aerodynamics. features oversized tires, a full-suspension frame, two disc brakes and handlebars oriented perpendicular to the bike's axis is sometimes called a chainless bicycle

The bicycle, bike, or cycle, is a bicycle pedal, human-powered transport with two bicycle wheel attached to a bicycle frame, one behind the other.

First introduced in 19th century, bicycles now number approximately one billion worldwide,DidYouKnow.cd. There are about a billion bicycles in the world. Retrieved 30 July 2006. providing the principal means of transportation in many regions, notably China and the Netherlands. They also provide 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 police applications, courier services, and cycle sports.

The basic shape and configuration of a typical bicycle has hardly changed since the first chain-driven model was developed around 1885,{{cite book].

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

Several innovators contributed to the history of the bicycle by developing precursor human-powered vehicles, including the velocipede. The documented ancestors of today's modern bicycle were known as pushbikes, Dandy horse or hobby horses. To use the Draisine, first introduced to the public in Paris by the Germany Freiherr Karl Drais in 1818{{cite web| title = Canada Science and Technology Museum: Baron von Drais’ Bicycle| year = 2006| url = http://www.sciencetech.technomuses.ca/english/collection/cycles2.cfm| accessdate = 2006-12-23-->, the operator sat astride a wooden frame supported by two in-line wheels and pushed the vehicle along with his/her feet while steering the front wheel.

or ordinary bicycle photographed in the Škoda museum in the Czech Republic

Scotland blacksmith Kirkpatrick MacMillan refined this in 1839 by adding a mechanical Crank (mechanism) drive to the rear wheel, thus creating the first true "bicycle" in the modern sense. In the 1850s and 1860s, Frenchmen Pierre Michaux and Pierre Lallement took bicycle design in a different direction, placing the pedals on an enlarged front wheel. Their creation, of wrought iron and wood, developed into the "penny-farthing" (more formally an penny-farthing), featuring a tubular steel frame on which were mounted wire spoked wheels with solid rubber tires. These bicycles were not, however, for the faint hearted, due to the very high seat and poor weight distribution.

The subsequent dwarf ordinary addressed some of these faults by reducing the front wheel diameter and setting the seat further back, necessitating the addition of gearing, effected in a variety of ways, to attain sufficient speed. However, having to both pedal and steer via the front wheel remained a problem. Starley's nephew, John Kemp Starley, J. H. Lawson, and Shergold solved this problem by introducing the chain drive connecting the pedals held with the frame to the back wheel. 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.



New innovations increased comfort, and ushered in a second bicycle craze, 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 Bicycle brake systems were also developed during these years, but were only slowly adopted by casual riders. By the turn of the century, cycling clubs flourished on both sides of the Atlantic, and touring and racing were soon extremely popular.

Bicycles and horse buggies were the two mainstays of private transportation just prior to the automobile, and the grading of smooth roads in the late 19th century was stimulated by the wide use of these devices.

Technical aspects Legal requirements image:Bycicle_diagram.svg

The 1968 Vienna Convention on Road Traffic of the United Nations 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 offence to use a bicycle that is not in roadworthy condition. In most places when ridden after dark, bicycles must have functioning front and rear bicycle lighting, or "lamps". As some generator or dynamo-driven lamps only operate while moving, rear retroreflectors are frequently also mandatory. Since a moving bicycle makes little noise, some countries insist that bicycles have a warning bell for use when approaching pedestrians, equestrians and other bicyclists.

Standards A number of formal and industry standards exist for bicycle components, to help make spare parts exchangeable:



Construction and parts Wheels 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 (bicycle part), the set of bearings that allows the bicycle fork to turn smoothly for steering and balance. 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 bicycle chain, connecting the bottom bracket to the rear Dropout (bicycle part). The seat stays connect the top of the seat tube (at or near the same point as the top tube) to the rear dropouts.

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. 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. Because of its persistent image as a "women's" bicycle, step-through frames are not common for larger builds.

Historically, materials used in bicycles have followed a similar pattern as in aircraft, the goal being high 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 fiber and titanium frames are now also available, as well as advanced steel alloys.

Drivetrain on the rear wheel of a shaft-driven bicycleThe drivetrain begins with bicycle pedal which rotate the Crank set, which are held in axis by the bottom bracket. Attached to one crank arm may be one or more chainrings or sprockets which drive the bicycle chain, which in turn rotates the rear wheel via the rear sprockets (cassette (bicycle part) or freewheel). A bicycle gearing is used to vary the number of rear wheel revolutions produced by each turn of the pedals.

Since cyclists' legs are most efficient over a narrow range of Cadence (cycling), a variable gear ratio is helpful to maintain an optimum pedalling speed while covering varied terrain.

When the bicycle chain shifts to a larger rear sprocket, or to a smaller front sprocket (a lower gear) every turn of the pedal leads to fewer rotations in the freewheel (and hence the rear wheel). This allows the force required to move the same distance to be distributed over more pedal cycles, reducing fatigue when riding uphill, with a heavy load, or against strong winds. The reverse process allows the cyclist to make fewer pedal cycles to maintain a higher speed, but with more effort per cycle.

Road bicycles have close set multi-step gearing, which allows fine control of cadence, while utility bicycles offer fewer, more widely spaced speeds. Mountain bikes, Touring bicycle and many entry-level racing bicycles offer an extremely low gear to facilitate climbing slowly on steep hills. Single-speed bicycles have only one gear combination.

Steering and seating The Bicycle handlebar turn the bicycle fork and the front wheel via the Stem (bike), which rotates within the headset (bicycle part). 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 can provide better low-speed handling due to the wider nature of the bars.

Bicycle saddle also vary with rider preference, from the cushioned ones favoured by short-distance riders to narrower saddles which allow more room for 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. Differing saddle designs exist for male and female cyclists, accommodating the genders' differing anatomy, although bikes typically are sold with saddles most appropriate for males.

A recumbent bicycle has a reclined Bicycle seat that some riders find more comfortable than a saddle, especially riders who suffer from certain types of seat, back, neck, shoulder, or wrist pain. Recumbent bicycles may have either under-seat or over-seat Recumbent bicycle#Steering.

Brakes

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. Disc brakes are common on off-road bicycles, tandem bicycles and recumbent bicycles, but are considered impractical on road bicycles, which rarely encounter conditions where the advantages of discs are significant. Hub drum brakes do not cope well with extended braking, so rim or disc brakes are favoured in hilly terrain.

With hand-operated brakes, force is applied to brake levers mounted on the handlebars and transmitted via Bowden cables or hydraulic lines to the friction pads. A rear hub brake may be either hand-operated or pedal-actuated, as in the back pedal coaster brakes which were popular in North America until the 1960s, and are still common in children's bicycles.

Track bicycles do not have brakes. Brakes are not required for riding on a track because all riders ride in the same direction around a track which does not necessitate sharp deceleration. Track riders are still able to slow down because all track bicycles are Fixed-gear bicycle, 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. While it is illegal in most jurisdictions to cycle on roads without brakes, a fixed-gear bike without brakes can be slowed by skidding the rear wheel. This involves unweighting the rear wheel and applying a backwards force to the pedals, causing the rear wheel to lock up and slide along the road. 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 designed their track frames to enable the fitting of brakes.

Suspension Bicycle suspension refers to the system or systems used to suspend the rider and all or part of the bicycle in order to protect them from the roughness of the terrain over which they travel. Bicycle suspension are used primarily on mountain bicycles, but are also common on hybrid bicycles, and can even be found on some road bicycles as they can help deal with problematic vibration.

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. Mudguards (or fenders) protect the cyclist and moving parts from spray when riding through wet areas and chainguards protect clothes from oil on the chain. Kick stands keep a bicycle upright when parked. Front-mounted bicycle basket for carrying goods are often used. Bicycle rack#Bicycle mounted bike racks and panniers or other carriers can be used to carry equipment or cargo. Parents sometimes add rear-mounted child seats and/or an auxiliary saddle fitted to the crossbar to transport children.

Toe-clips and toestraps and Bicycle pedal#Clipless pedals help to keep the foot planted firmly in the proper position on the pedals, and enable the cyclist to pull as well as push the pedals. Technical accessories include cyclocomputers for measuring speed and distance. Other accessories include bicycle lighting, reflectors, Bicycle pump, Bicycle lock, mirror, and bell.

Bicycle helmets may help reduce injury in the event of a collision or accident, and a certified helmet is legally required for some riders in some jurisdictions. Helmets are classified as an accessory or 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 hex wrenches. 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 repair and maintenance to professional bicycle mechanics. Others maintain their own bicycles, enhancing their enjoyment of the hobby of cycling.

In some areas it is possible to purchase road-side assistance from companies 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."Bicycle Technology", S.S. Wilson, Scientific American, March 1973 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%. "Johns Hopkins Gazette",30 August 1999{{cite book] 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. On an upright bicycle, the rider's body creates about 75% of the total drag of the bicycle/rider combination.

In addition, the carbon dioxide generated in the production and transportation of the food required by the bicyclist, per mile traveled, is less than 1/10th that generated by energy efficient cars.http://www.kenkifer.com/bikepages/advocacy/bike_co2.htm

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 bike, 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, endo or front wheelie .

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



Social and historical aspects

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 Bearing (mechanical), washer (mechanical)s, 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 (car) auto maker. The Morris Motor Company (in Oxford) and Škoda Auto also began in the bicycle business, as did the Wright Brothers.{{cite web] 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.The Economist, 15 February 2003

Female emancipation The diamond-frame safety bicycle gave women unprecedented mobility, contributing to Emancipation of women 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, untrammelled 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 University of Cambridge 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.http://www.newn.cam.ac.uk/about/about_history2.shtml

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 (clothing).

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.

Uses for bicycles Bicycles have been and are employed for many uses.

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 common types include utility bicycles, mountain bicycles, racing bicycles, touring bicycles, cruiser bicycles, and BMX bicycles. Less common types include tandem bicycle, recumbent bicycle, Lowrider bicycle, tall bikes, Fixed-gear bicycle, and folding bicycle. Unicycles, tricycles and quadracycles are not strictly bicycles, as they have respectively one, three and four wheels, but are often referred to informally as "bikes".

See also

General

Special uses and related vehicle types Other

Notes

References

External links



is built using lightweight, shaped aluminium tubing and Graphite-reinforced plastic stays and forks. It sports a drop handlebar and thin tires and wheels for efficiency and aerodynamics. features oversized tires, a full-suspension frame, two disc brakes and handlebars oriented perpendicular to the bike's axis is sometimes called a chainless bicycle

The bicycle, bike, or cycle, is a bicycle pedal, human-powered transport with two bicycle wheel attached to a bicycle frame, one behind the other.

First introduced in 19th century, bicycles now number approximately one billion worldwide,DidYouKnow.cd. There are about a billion bicycles in the world. Retrieved 30 July 2006. providing the principal means of transportation in many regions, notably China and the Netherlands. They also provide 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 police applications, courier services, and cycle sports.

The basic shape and configuration of a typical bicycle has hardly changed since the first chain-driven model was developed around 1885,{{cite book].

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

Several innovators contributed to the history of the bicycle by developing precursor human-powered vehicles, including the velocipede. The documented ancestors of today's modern bicycle were known as pushbikes, Dandy horse or hobby horses. To use the Draisine, first introduced to the public in Paris by the Germany Freiherr Karl Drais in 1818{{cite web| title = Canada Science and Technology Museum: Baron von Drais’ Bicycle| year = 2006| url = http://www.sciencetech.technomuses.ca/english/collection/cycles2.cfm| accessdate = 2006-12-23-->, the operator sat astride a wooden frame supported by two in-line wheels and pushed the vehicle along with his/her feet while steering the front wheel.

or ordinary bicycle photographed in the Škoda museum in the Czech Republic

Scotland blacksmith Kirkpatrick MacMillan refined this in 1839 by adding a mechanical Crank (mechanism) drive to the rear wheel, thus creating the first true "bicycle" in the modern sense. In the 1850s and 1860s, Frenchmen Pierre Michaux and Pierre Lallement took bicycle design in a different direction, placing the pedals on an enlarged front wheel. Their creation, of wrought iron and wood, developed into the "penny-farthing" (more formally an penny-farthing), featuring a tubular steel frame on which were mounted wire spoked wheels with solid rubber tires. These bicycles were not, however, for the faint hearted, due to the very high seat and poor weight distribution.

The subsequent dwarf ordinary addressed some of these faults by reducing the front wheel diameter and setting the seat further back, necessitating the addition of gearing, effected in a variety of ways, to attain sufficient speed. However, having to both pedal and steer via the front wheel remained a problem. Starley's nephew, John Kemp Starley, J. H. Lawson, and Shergold solved this problem by introducing the chain drive connecting the pedals held with the frame to the back wheel. 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.



New innovations increased comfort, and ushered in a second bicycle craze, 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 Bicycle brake systems were also developed during these years, but were only slowly adopted by casual riders. By the turn of the century, cycling clubs flourished on both sides of the Atlantic, and touring and racing were soon extremely popular.

Bicycles and horse buggies were the two mainstays of private transportation just prior to the automobile, and the grading of smooth roads in the late 19th century was stimulated by the wide use of these devices.

Technical aspects Legal requirements image:Bycicle_diagram.svg

The 1968 Vienna Convention on Road Traffic of the United Nations 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 offence to use a bicycle that is not in roadworthy condition. In most places when ridden after dark, bicycles must have functioning front and rear bicycle lighting, or "lamps". As some generator or dynamo-driven lamps only operate while moving, rear retroreflectors are frequently also mandatory. Since a moving bicycle makes little noise, some countries insist that bicycles have a warning bell for use when approaching pedestrians, equestrians and other bicyclists.

Standards A number of formal and industry standards exist for bicycle components, to help make spare parts exchangeable:



Construction and parts Wheels 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 (bicycle part), the set of bearings that allows the bicycle fork to turn smoothly for steering and balance. 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 bicycle chain, connecting the bottom bracket to the rear Dropout (bicycle part). The seat stays connect the top of the seat tube (at or near the same point as the top tube) to the rear dropouts.

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. 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. Because of its persistent image as a "women's" bicycle, step-through frames are not common for larger builds.

Historically, materials used in bicycles have followed a similar pattern as in aircraft, the goal being high 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 fiber and titanium frames are now also available, as well as advanced steel alloys.

Drivetrain on the rear wheel of a shaft-driven bicycleThe drivetrain begins with bicycle pedal which rotate the Crank set, which are held in axis by the bottom bracket. Attached to one crank arm may be one or more chainrings or sprockets which drive the bicycle chain, which in turn rotates the rear wheel via the rear sprockets (cassette (bicycle part) or freewheel). A bicycle gearing is used to vary the number of rear wheel revolutions produced by each turn of the pedals.

Since cyclists' legs are most efficient over a narrow range of Cadence (cycling), a variable gear ratio is helpful to maintain an optimum pedalling speed while covering varied terrain.

When the bicycle chain shifts to a larger rear sprocket, or to a smaller front sprocket (a lower gear) every turn of the pedal leads to fewer rotations in the freewheel (and hence the rear wheel). This allows the force required to move the same distance to be distributed over more pedal cycles, reducing fatigue when riding uphill, with a heavy load, or against strong winds. The reverse process allows the cyclist to make fewer pedal cycles to maintain a higher speed, but with more effort per cycle.

Road bicycles have close set multi-step gearing, which allows fine control of cadence, while utility bicycles offer fewer, more widely spaced speeds. Mountain bikes, Touring bicycle and many entry-level racing bicycles offer an extremely low gear to facilitate climbing slowly on steep hills. Single-speed bicycles have only one gear combination.

Steering and seating The Bicycle handlebar turn the bicycle fork and the front wheel via the Stem (bike), which rotates within the headset (bicycle part). 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 can provide better low-speed handling due to the wider nature of the bars.

Bicycle saddle also vary with rider preference, from the cushioned ones favoured by short-distance riders to narrower saddles which allow more room for 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. Differing saddle designs exist for male and female cyclists, accommodating the genders' differing anatomy, although bikes typically are sold with saddles most appropriate for males.

A recumbent bicycle has a reclined Bicycle seat that some riders find more comfortable than a saddle, especially riders who suffer from certain types of seat, back, neck, shoulder, or wrist pain. Recumbent bicycles may have either under-seat or over-seat Recumbent bicycle#Steering.

Brakes

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. Disc brakes are common on off-road bicycles, tandem bicycles and recumbent bicycles, but are considered impractical on road bicycles, which rarely encounter conditions where the advantages of discs are significant. Hub drum brakes do not cope well with extended braking, so rim or disc brakes are favoured in hilly terrain.

With hand-operated brakes, force is applied to brake levers mounted on the handlebars and transmitted via Bowden cables or hydraulic lines to the friction pads. A rear hub brake may be either hand-operated or pedal-actuated, as in the back pedal coaster brakes which were popular in North America until the 1960s, and are still common in children's bicycles.

Track bicycles do not have brakes. Brakes are not required for riding on a track because all riders ride in the same direction around a track which does not necessitate sharp deceleration. Track riders are still able to slow down because all track bicycles are Fixed-gear bicycle, 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. While it is illegal in most jurisdictions to cycle on roads without brakes, a fixed-gear bike without brakes can be slowed by skidding the rear wheel. This involves unweighting the rear wheel and applying a backwards force to the pedals, causing the rear wheel to lock up and slide along the road. 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 designed their track frames to enable the fitting of brakes.

Suspension Bicycle suspension refers to the system or systems used to suspend the rider and all or part of the bicycle in order to protect them from the roughness of the terrain over which they travel. Bicycle suspension are used primarily on mountain bicycles, but are also common on hybrid bicycles, and can even be found on some road bicycles as they can help deal with problematic vibration.

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. Mudguards (or fenders) protect the cyclist and moving parts from spray when riding through wet areas and chainguards protect clothes from oil on the chain. Kick stands keep a bicycle upright when parked. Front-mounted bicycle basket for carrying goods are often used. Bicycle rack#Bicycle mounted bike racks and panniers or other carriers can be used to carry equipment or cargo. Parents sometimes add rear-mounted child seats and/or an auxiliary saddle fitted to the crossbar to transport children.

Toe-clips and toestraps and Bicycle pedal#Clipless pedals help to keep the foot planted firmly in the proper position on the pedals, and enable the cyclist to pull as well as push the pedals. Technical accessories include cyclocomputers for measuring speed and distance. Other accessories include bicycle lighting, reflectors, Bicycle pump, Bicycle lock, mirror, and bell.

Bicycle helmets may help reduce injury in the event of a collision or accident, and a certified helmet is legally required for some riders in some jurisdictions. Helmets are classified as an accessory or 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 hex wrenches. 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 repair and maintenance to professional bicycle mechanics. Others maintain their own bicycles, enhancing their enjoyment of the hobby of cycling.

In some areas it is possible to purchase road-side assistance from companies 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."Bicycle Technology", S.S. Wilson, Scientific American, March 1973 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%. "Johns Hopkins Gazette",30 August 1999{{cite book] 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. On an upright bicycle, the rider's body creates about 75% of the total drag of the bicycle/rider combination.

In addition, the carbon dioxide generated in the production and transportation of the food required by the bicyclist, per mile traveled, is less than 1/10th that generated by energy efficient cars.http://www.kenkifer.com/bikepages/advocacy/bike_co2.htm

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 bike, 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, endo or front wheelie .

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



Social and historical aspects

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 Bearing (mechanical), washer (mechanical)s, 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 (car) auto maker. The Morris Motor Company (in Oxford) and Škoda Auto also began in the bicycle business, as did the Wright Brothers.{{cite web] 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.The Economist, 15 February 2003

Female emancipation The diamond-frame safety bicycle gave women unprecedented mobility, contributing to Emancipation of women 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, untrammelled 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 University of Cambridge 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.http://www.newn.cam.ac.uk/about/about_history2.shtml

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 (clothing).

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.

Uses for bicycles Bicycles have been and are employed for many uses.

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 common types include utility bicycles, mountain bicycles, racing bicycles, touring bicycles, cruiser bicycles, and BMX bicycles. Less common types include tandem bicycle, recumbent bicycle, Lowrider bicycle, tall bikes, Fixed-gear bicycle, and folding bicycle. Unicycles, tricycles and quadracycles are not strictly bicycles, as they have respectively one, three and four wheels, but are often referred to informally as "bikes".

See also

General

Special uses and related vehicle types Other

Notes

References

External links



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