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In the 1850s and 1860s, Frenchman Ernest Michaux and his pupil Pierre Lallement took bicycle design in a different direction, placing 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 America, where he recorded a patent on his bicycle in 1866 in [[New Haven, Connecticut]]. The Boneshaker was further refined by 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.
''[[Image:BicyclePlymouth.jpg|left|thumb|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.
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{{details|bicycle gearing}}
 
The ''drivetrain'' begins with [[bicycle pedal|pedals]] which rotate the [[crankset]], which fit into the [[bottom bracket]]. Attached to the crank is the ''chainring'' which drives the [[bicycle chain|chain]], which in turn rotates the rear wheel via the rear [[sprocket]]s. Between the chain and rear wheel may be interspersed various [[bicycle gearing|gearing systems]], described below, which 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 ''[[Cadence (cycling)|cadences]]'', a variable [[gear ratio]] is needed to maintain an optimum pedaling speed while covering varied terrain. The gear systems are hand-operated, via cables (or rarely, hydraulics), and are of two types.
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Variations on these styles exist. ''Bullhorn'' style handlebars are often seen on modern [[time trial bicycle]]s, equipped with two forward-facing extensions, allowing a rider to rest his 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 ''Bullhhorn'' was banned from ordinary road racing because it is difficult for the rider to control in bike traffic.
 
''Seats'', or ''saddles'', also vary with rider preference, from the cushioned ones favoured by short-distance riders to narrower seats 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.
 
[[Recumbent bicycle]]s have more chair-like seats, and so are much more comfortable to ride, although generally slower up hills due to this positioning. The reclined, low seating position does provide increased aerodynamics over standard seating.
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{{main|bicycle brake systems}}
 
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 cable]]s to the friction pads. In the late 1990s, [[disc brakes]] appeared on some off-road bicycles, [[tandem bicycle|tandem]]s and [[recumbent bicycle]]s, 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.
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For many people whose running might be limited by muscle and knee pain, cycling offers comparable outdoor exercise that can be enjoyed by people of a wide range of fitness levels: it is a "no-impact" sport that is easy on the body as long as the bike is properly "fit." In addition, since bicycling can also provide convenient transportation, less self-discipline may be required to keep to the activity, since it has a practical purpose. However, because of its efficiency, cycling requires a longer distance, and often greater time, than running to consume the same amount of energy.
 
The average "in-shape" man can produce about 3 watts/kg for more than an hour (e.g., around 200 watts for a 70 kg rider), with top amateurs producing 5 watts/kg and elite athletes achieving 6 watts/kg for similar lengths of time. Elite track sprinters are able to attain an instantaneous maximum output of around 2,000 watts, or in excess of 25 watts/kg; elite road cyclists may produce 1,600 to 1,700 watts as an instantaneous maximum in their burst to the finish line at the end of a five-hour long road race. Even at moderate speeds, most cycling energy is spent in overcoming aerodynamic [[drag (physics)|drag]], which increases with the square of speed; therefore, power needs increase approximately with the cube of speed.
 
Typical speeds for bicycles are 16 to 32 [[km/h]] (10 to 20 [[Miles per hour|mph]]). On a fast racing bicycle, a reasonably fit rider can ride at 50 km/h (30 mph) on flat ground for short periods. The highest speed ever officially attained on the flat, without using motor pacing and wind-blocks, is by Canadian [[Sam Whittingham]], who in 2002 set a 130.36 km/h (81.00 mph) record on his highly aerodynamic [[recumbent bicycle]]. This stands as the official record for all human-powered vehicles.
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* [[Art bike]]s: Some bikes are built so that the frame appears to be made of junk or found objects: [[Bongo the Clown]] built several ridable parade bikes which were as much kinetic sculptures as transport.
 
* A ''[[unicycle]]'' is not a bicycle, as it has only one wheel, but it is related.
 
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