ratio of word probabilities predicted from brain for cow and bicycle

cow	bicycle
top 10 words in brain distribution (in article): animal species cat breed male human dog wild record female	top 10 words in brain distribution (in article): fiber city build town state century Unite produce country time
top 10 words in brain distribution (not in article): wolf hunt card bear lion elephant tiger service prey information	top 10 words in brain distribution (not in article): sheep house store wool cotton street fabric weave home hamlet
times more probable under cow 30 20 10 6 4 2.5 1.25 1 1.25 2.5 4 6 10 20 30 times more probable under bicycle (words not in the model)
Cattle'", colloquially referred to as "'cows'", are domesticated ungulates, a member of the subfamily Bovinae of the family Bovidae. They are raised as livestock for meat (called beef and veal), dairy products (milk), leather and as draft animals (pulling carts, plows and the like). In some countries, such as India, they are honored in religious ceremonies and revered. It is estimated that there are 1.3 billion cattle in the world today. Species of cattle. Cattle were originally identified by Carolus Linnaeus as three separate species. These were "Bos taurus", the European cattle, including similar types from Africa and Asia; "Bos indicus", the zebu; and the extinct "Bos primigenius", the aurochs. The aurochs is ancestral to both zebu and European cattle. More recently these three have increasingly been grouped as one species, with "Bos primigenius taurus", "Bos primigenius indicus" and "Bos primigenius primigenius" as the subspecies. Complicating the matter is the ability of cattle to interbreed with other closely related species. Hybrid individuals and even breeds exist, not only between European cattle and zebu but also with yaks (called a dzo), banteng, gaur, and bison ("cattalo"), a cross-genera hybrid. For example, genetic testing of the Dwarf Lulu breed, the only humpless "Bos taurus"-type" cattle in Nepal, found them to be a mix of European cattle, zebu and yak. Cattle cannot successfully be bred with water buffalo or African buffalo. The aurochs originally ranged throughout Europe, North Africa, and much of Asia. In historical times, their range was restricted to Europe, and the last animals were killed by poachers in Masovia, Poland, in 1627. Breeders have attempted to recreate cattle of similar appearance to aurochs by crossing of domesticated cattle breeds, creating the Heck cattle breed. (See also aurochs and zebu articles.) Word origin. "Cattle" did not originate as a name for bovine animals. It derives from the Latin "caput", head, and originally meant movable property, especially livestock of any kind. The word is closely related to "chattel" (a unit of personal property) and "capital" in the economic sense. Older English sources like King James Version of the Bible refer to livestock in general as cattle (as opposed to the word deer which then was used for wild animals). Additionally other species of the genus "Bos" are sometimes called wild cattle. Today, the modern meaning of "cattle", without any other qualifier, is usually restricted to domesticated bovines. Terminology of cattle. In general, the same words are used in different parts of the world but with minor differences in the definitions. The terminology described here contrasts the differences in definition between the United States and other British influenced parts of world such as Canada, Australia, New Zealand, Ireland, and the United Kingdom. Singular terminology dilemma. "Cattle" can only be used in the plural and not in the singular: it is a plurale tantum. Thus one may refer to "three cattle" or "some cattle", but not "one cattle". There is no universally used singular equivalent in modern English to "cattle", other than the gender and age-specific terms such as cow, bull, steer and heifer. Strictly speaking, the singular noun for the domestic bovine was "ox", however, "ox" today is rarely used in this general sense. An ox today generally denotes a draft beast, most commonly a castrated male (but is not to be confused with the unrelated wild musk ox). "Cow" has been in general use as a singular for the collective "cattle" in spite of the objections of those who say that it is a female-specific term, so that that phrases such as "that cow is a bull" would be absurd from a lexicographic standpoint. However, it is easy to use when a singular is needed and the gender is not known, as in "There is a cow in the road". Further, any herd of fully mature cattle in or near a pasture is statistically likely to consist mostly of cows, so the term is probably accurate even in the restrictive sense. Other than the few bulls needed for breeding, the vast majority of male cattle are castrated as calves and slaughtered for meat before the age of three years. Thus, in a pastured herd, any calves or herd bulls usually are clearly distinguishable from the cows due to distinctively different sizes and clear anatomical differences. The Oxford English Dictionary lists the use of "cows" as a synonym for "cattle" as an American usage. Merriam-Webster, a U.S. dictionary, recognizes the non-gender-specific use of "cow" as an alternate definition, whereas Collins, a UK dictionary, does not. Colloquially, more general non-specific terms may denote cattle when a singular form is needed. Australian, New Zealand and British farmers use the term "beast" or "cattle beast". "Bovine" is also used in Britain. The term "critter" is common in the western United States and Canada, particularly when referring to young cattle. In some areas of the American South (particularly the Appalachian region), where both dairy and beef cattle are present, an individual animal was once called a "beef critter", though that term is becoming archaic. Other terminology. Cattle raised for human consumption are called "beef cattle". Within the beef cattle industry in parts of the United States, the term "beef" (plural "beeves") is still used in its archaic sense to refer to an animal of either gender. Cows of certain breeds that are kept for the milk they give are called "dairy cows" or "milking cows" (formerly "milch cows" – "milch" was pronounced as "milk"). Most young male offspring of dairy cows are sold for veal, and may be referred to as "veal calves." The term "dogies" was once used to describe calves and young steers in the context of ranch work in the American west, as in "Keep them dogies moving," but in modern use is considered archaic unless used in a humorous context. In some places, a cow kept to provide milk for one family is called a "house cow". Other obsolete terms for cattle include "neat" (this use survives in "neatsfoot oil", extracted from the feet and legs of cattle), and "beefing" (young animal fit for slaughter). An onomatopoeic term for one of the commonest sounds made by cattle is "moo", and this sound is also called "lowing". There are a number of other sounds made by cattle, including calves "bawling", and bulls "bellowing" (a high-pitched yodeling call). The bullroarer makes a sound similar to a territorial call made by bulls. Anatomy. Cattle have one stomach with four compartments. They are the rumen, reticulum, omasum, and abomasum, the rumen being the largest compartment. Cattle sometimes consume metal objects which are deposited in the reticulum, the smallest compartment, and this is where hardware disease occurs. The reticulum is known as the "Honeycomb." The omasum's main function is to absorb water and nutrients from the digestible feed. The omasum is known as the "Many Plies." The abomasum is like the human stomach; this is why it is known as the "true stomach". Cattle are ruminants, meaning that they have a digestive system that allows use of otherwise indigestible foods by repeatedly regurgitating and rechewing them as "cud". The cud is then reswallowed and further digested by specialised microorganisms in the rumen. These microbes are primarily responsible for decomposing cellulose and other carbohydrates into volatile fatty acids that cattle use as their primary metabolic fuel. The microbes inside of the rumen are also able to synthesize amino acids from non-protein nitrogenous sources such as urea and ammonia. As these microbes reproduce in the rumen, older generations die and their carcasses continue on through the digestive tract. These carcasses are then partially digested by the cattle, allowing it to gain a high quality protein source. These features allow cattle to thrive on grasses and other vegetation. The gestation period for a cow is nine months. A newborn calf weighs. The world record for the heaviest bull was a Chianina named Donetto, when he was exhibited at the Arezzo show in 1955. The heaviest steer was eight year old ‘Old Ben’, a Shorthorn Hereford cross weighing in at in 1910. Steers are generally killed before reaching. Breeding stock usually live to about 15 years (occasionally as much as 25 years). A common misconception about cattle (particularly bulls) is that they are enraged by the color red (something provocative is often said to be "like a red flag to a bull"). This is incorrect, as cattle are red-green color-blind. The myth arose from the use of red capes in the sport of bullfighting; in fact, two different capes are used. The capote is a large, flowing cape that is magenta and yellow. The more famous muleta is the smaller, red cape, used exclusively for the final, fatal segment of the fight. It is not the color of the cape that angers the bull, but rather the movement of the fabric that irritates the bull and incites it to charge. Although cattle cannot distinguish red from green, they do have two kinds of color receptors in their retinas (cone cells) and so are theoretically able to distinguish some colors, probably in a similar way to other red-green color-blind or dichromatic mammals (such as dogs, cats, horses and up to ten percent of male humans). Domestication and husbandry. Cattle occupy a unique role in human history, domesticated since at least the early Neolithic. They are raised for meat (beef cattle), dairy products and hides. They are also used as draft animals and in certain sports. Some consider cattle the oldest form of wealth, and cattle raiding consequently one of the earliest forms of theft. Cattle are often raised by allowing herds to graze on the grasses of large tracts of rangeland. Raising cattle in this manner allows the use of land that might be unsuitable for growing crops. The most common interactions with cattle involve daily feeding, cleaning and milking. Many routine husbandry practices involve ear tagging, dehorning, loading, medical operations, vaccinations and hoof care, as well as training for agricultural shows and preparations. There are also some cultural differences in working with cattle- the cattle husbandry of Fulani men rests on behavioural techniques, whereas in Europe cattle are controlled primarily by physical means like fences. Breeders utilise cattle husbandry to reduce M. bovis infection susceptibility by selective breeding and maintaining herd health to avoid concurrent disease. Cattle are farmed for beef, veal, dairy, leather and they are less commonly used simply to maintain grassland for wildlife- for example, in Epping Forest, England. They are often used in some of the most wild places for livestock. Depending on the breed, cattle can survive on hill grazing, heaths, marshes, moors and semi desert. Modern cows are more commercial than older breeds and, having become more specialized, are less versatile. For this reason many smaller farmers still favor old breeds, like the dairy breed of cattle Jersey. In Portugal, Spain, Southern France and some Latin American countries, bulls are used in the activity of bullfighting; a similar activity, Jallikattu, is seen in South India; in many other countries this is illegal. Other activities such as bull riding are seen as part of a rodeo, especially in North America. Bull-leaping, a central ritual in Bronze Age Minoan culture (see Bull (mythology)), still exists in southwestern France. In modern times, cattle are also entered into agricultural competitions. These competitions can involve live cattle or cattle carcasses. In terms of food intake by humans, consumption of cattle is less efficient than of grain or vegetables with regard to land use, and hence cattle grazing consumes more area than such other agricultural production. Nonetheless, cattle and other forms of domesticated animals can sometimes help to utilize plant resources in areas not easily amenable to other forms of agriculture. These factors were not as important in earlier times prior to the Earth's large human population. Environmental impact. A 400-page United Nations report from the Food and Agriculture Organization (FAO) states that cattle farming is "responsible for 18% of greenhouse gases." The production of cattle to feed and clothe humans stresses ecosystems around the world, and is assessed to be one of the top three environmental problems in the world on a local to global scale. The report, entitled "Livestock's Long Shadow", also surveys the environmental damage from sheep, chickens, pigs and goats. But in almost every case, the world's 1.5 billion cattle are cited as the greatest adverse impact with respect to climate change as well as species extinction. The report concludes that, unless changes are made, the massive damage reckoned to be due to livestock may more than double by 2050, as demand for meat increases. One of the cited changes suggests that intensification of the livestock industry may be suggested, since intensification leads to less land for a given level of production. Some microbes respire in the cattle gut by an anaerobic process known as methanogenesis (producing the gas methane). Cattle emit a large volume of methane, 95% of it through eructation or burping, not flatulence. As the carbon in the methane comes from the digestion of vegetation produced by photosynthesis, its release into the air by this process would normally be considered harmless, because there is no net increase in carbon in the atmosphere — it's removed as carbon dioxide from the air by photosynthesis and returned to it as methane. Methane is a more potent greenhouse gas than carbon dioxide, having a warming effect 23 to 50 times greater, and according to Takahashi and Young "even a small increase in methane concentration in the atmosphere exerts a potentially significant contribution to global warming". Further analysis to the methane gas produced by livestock as a contributor to the increase in greenhouse gases is provided by Weart. Research is underway on methods of reducing this source of methane, by the use of dietary supplements, or treatments to reduce the proportion of methanogenetic microbes, perhaps by vaccination. Cattle are fed a concentrated high-corn diet which produces rapid weight gain, but this has side effects which include increased acidity in the digestive system. When improperly handled, manure and other byproducts of concentrated agriculture also have environmental consequences. Grazing by cattle at low intensities can create a favourable environment for native herbs and forbs; however, in most world regions cattle are reducing biodiversity due to overgrazing driven by food demands by an expanding human population. Oxen== Oxen'" (singular "'ox'") are large and heavyset breeds of "Bos taurus" cattle trained as draft animals. Often they are adult, castrated males. Usually an ox is over four years old due to the need for training and to allow it to grow to full size. Oxen are used for plowing, transport, hauling cargo, grain-grinding by trampling or by powering machines, irrigation by powering pumps, and wagon drawing. Oxen were commonly used to skid logs in forests, and sometimes still are, in low-impact select-cut logging. Oxen are most often used in teams of two, paired, for light work such as carting. In the past, teams might have been larger, with some teams exceeding twenty animals when used for logging. An ox is nothing more than a mature bovine with an "education." The education consists of the animal's learning to respond appropriately to the teamster's (ox driver's) signals. These signals are given by verbal commands or by noise (whip cracks) and many teamsters were known for their voices and language. In North America, the commands are (1) "get up", (2) "whoa", (3) "back up", (4) "gee" (turn right) and (5) "haw" (turn left). Oxen must be painstakingly trained from a young age. Their teamster must provide as many as a dozen yokes of different sizes as the animals grow. A wooden yoke is fastened about the neck of each pair so that the force of draft is distributed across their shoulders. From calves, oxen are chosen with horns since the horns hold the yoke in place when the oxen lower their heads, back up, or slow down (particularly with a wheeled vehicle going downhill). Yoked oxen cannot slow a load like harnessed horses can; the load has to be controlled downhill by other means. The gait of the ox is often important to ox trainers, since the speed the animal walks should roughly match the gait of the ox driver who must work with it. U.S. ox trainers favored larger breeds for their ability to do more work and for their intelligence. Because they are larger animals, the typical ox is the male of a breed, rather than the smaller female. Females are potentially more useful producing calves and milk. Oxen can pull harder and longer than horses, particularly on obstinate or almost un-movable loads. This is one of the reasons that teams drag logs from forests long after horses had taken over most other draft uses in Europe and North America. Though not as fast as horses, they are less prone to injury because they are more sure-footed and do not try to jerk the load. An "ox" is not a unique breed of bovine, nor have any "blue" oxen lived outside the folk tales surrounding Paul Bunyan, the mythical American logger. A possible exception and antecedent to this legend is the Belgian Blue breed which is known primarily for its unusual musculature and at times exhibits unusual white blue, blue roan, or blue coloration. The unusual musculature of the breed is believed to be due to a natural mutation of the gene that codes for the protein Myostatin, which is responsible for normal muscle atrophy. Many oxen are used worldwide, especially in developing countries. Ox is also used for various cattle products, irrespective of age, sex or training of the beast – for example, ox-blood, ox-liver, ox-kidney, ox-heart, ox-hide. Hindu tradition. Cows are venerated within the Hindu religion of India. According to Vedic scripture they are to be treated with the same respect 'as one's mother' because of the milk they provide; "The cow is my mother. The bull is my sire." They appear in numerous stories from the Puranas and Vedas, for example the deity Krishna is brought up in a family of cowherders, and given the name Govinda (protector of the cows). Also Shiva is traditionally said to ride on the back of a bull named Nandi. Bulls in particular are seen as a symbolic emblem of selfless duty and religion. In ancient rural India every household had a few cows which provided a constant supply of milk and a few bulls that helped as draft animals. Many Hindus feel that at least it was economically wise to keep cattle for their milk rather than consume their flesh for one single meal. Gandhi explains his feelings about cow protection as follows: "The cow to me means the entire sub-human world, extending man's sympathies beyond his own species. Man through the cow is enjoined to realize his identity with all that lives. Why the ancient rishis selected the cow for apotheosis is obvious to me. The cow in India was the best comparison; she was the giver of plenty. Not only did she give milk, but she also made agriculture possible. The cow is a poem of pity; one reads pity in the gentle animal. She is the second mother to millions of mankind. Protection of the cow means protection of the whole dumb creation of God. The appeal of the lower order of creation is all the more forceful because it is speechless." In heraldry. Cattle are typically represented in heraldry by the bull'". Present status. The world cattle population is estimated to be about 995,838,000 head. India is the nation with the largest number of cattle, about 281,700,000 or 28.29% of the world cattle population, followed by Brazil: 187,087,000, 18.79%; China: 139,721,000, 14.03%; the United States: 96,669,000, 9.71%; EU-27: at 87,650,000, 8.80%; Argentina: 51,062,000, 5.13%; Australia: 29,202,000, 2.93%; South Africa: 14,187,000, 1.42%; Canada: 13,945,000, 1.40% and other countries: 49,756,000 5.00%. Africa has about 20,000,000 head of cattle, many of which are raised in traditional ways and serve partly as tokens of their owner's wealth. Cattle today are the basis of a multi-billion dollar industry worldwide. The international trade in beef for 2000 was over $30 billion and represented only 23 percent of world beef production. (Clay 2004). The production of milk, which is also made into cheese, butter, yogurt, and other dairy products, is comparable in economic size to beef production and provides an important part of the food supply for many of the world's people. Cattle hides, used for leather to make shoes and clothing, are another widespread product. Cattle remain broadly used as draft animals in many developing countries, such as India.	The bicycle'", "'bike'", or "'cycle'" is a pedal-driven, human-powered vehicle with two wheels attached to a frame, one behind the other. Bicycles were introduced in the 19th century and now number about one billion worldwide. They are the principal means of transportation in many regions. They also provide a popular form of recreation, and have been adapted for such uses as children's toys, adult fitness, military and police applications, courier services, and competitive sports. The basic shape and configuration of a typical bicycle has changed little since the first chain-driven model was developed around 1885. Many details have been improved, especially since the advent of modern materials and computer-aided design. These have allowed for a proliferation of specialized designs for particular types of cycling. The bicycle has had a considerable effect on human society, 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 both to old and new areas. History. Multiple innovators contributed to the history of the bicycle by developing precursor human-powered vehicles. The documented ancestors of today's modern bicycle were known as push bikes (still called push bikes outside of North America), draisines, or hobby horses. Being the first human means of transport to make use of the two-wheeler principle, the draisine (or "mistmashine", "running machine"), invented by the German Baron Karl von Drais, is regarded as the archetype of the bicycle. It was introduced by Drais to the public in Mannheim in summer 1817 and in Paris in 1818. Its rider 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. In the early 1860s, Frenchmen Pierre Michaux and Pierre Lallement took bicycle design in a new direction by adding a mechanical crank drive with pedals on an enlarged front wheel. Another French inventor by the name of Douglas Grasso had a failed prototype of Pierre Lallement's bicycle several years earlier. Several why-not-the-rear-wheel inventions followed, the best known being the rod-driven velocipede by Scotsman Thomas McCall in 1869. The French creation, made of iron and wood, developed into the "penny-farthing" (more formally an "ordinary bicycle", a retronym, since there were then no other kind). It featured a tubular steel frame on which were mounted wire spoked wheels with solid rubber tires. These bicycles were difficult to ride due to their very high seat and poor weight distribution. The "dwarf ordinary" addressed some of these faults by reducing the front wheel diameter and setting the seat further back. This necessitated the addition of gearing, effected in a variety of ways, to attain sufficient speed. Having to both pedal and steer via the front wheel remained a problem. J. K. Starley, J. H. Lawson, and Shergold solved this problem by introducing the chain drive (originated by Henry Lawson's unsuccessful "bicyclette"), connecting the frame-mounted pedals to the rear 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. Further 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. 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, cycling clubs flourished on both sides of the Atlantic, and touring and racing became widely 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 widespread advertising, production, and use of these devices. Uses. Bicycles have been and are employed for many uses: Technical aspects. The bicycle has undergone continual adaptation and improvement since its inception. These innovations have continued with the advent of modern materials and computer-aided design, allowing for a proliferation of specialized bicycle types. Types. 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 more common types include utility bicycles, mountain bicycles, racing bicycles, touring bicycles, hybrid bicycles, cruiser bicycles, and BMX bicycles. Less common are tandems, lowriders, tall bikes, fixed gear (fixed-wheel), folding models and recumbents (one of which was used to set the IHPVA Hour record). 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". Dynamics. A bicycle stays upright while moving forward by being steered so as to keep its center of gravity over the wheels. This steering is usually provided by the rider, but under certain conditions may be provided by the bicycle itself. The combined center of mass of a bicycle and its rider must lean into a turn in order successfully navigate it. 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. The act of purposefully using this force to lift the rear wheel and balance on the front without tipping over is a trick known as a stoppie, endo or front wheelie. Performance. The bicycle is extraordinarily efficient in both biological and mechanical terms. The bicycle is the most efficient self-powered means of transportation in terms of energy a person must expend to travel a given distance. 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 traveling on a bicycle at low to medium speeds of around 10-15 mph (15-25 km h), uses only the energy required to walk, is the most energy-efficient means of transport generally available. Air drag, which is proportional to the square of speed, requires dramatically higher power outputs as speeds increase. If the rider is sitting upright, the rider's body creates about 75% of the total drag of the bicycle rider combination. Drag can be reduced by seating the rider in a supine position or a prone position, thus creating a recumbent bicycle or human powered vehicle. Drag can also be reduced by covering the bicycle with an aerodynamic fairing. 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. Construction and parts. In its early years, bicycle construction drew on pre-existing technologies. More recently, bicycle technology has in turn contributed ideas in both old and new areas. Frame. The great majority of today's bicycles have a frame with upright seating which looks much like the first chain-driven bike. Such upright bicycles almost always 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 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 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. 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, referred to as a "step-through frame", 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 variation, the "mixte", 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 frames. Another style is the recumbent bicycle. These are inherently more aerodynamic than upright versions, as the rider may lean back onto a support and operate pedals that are on about the same level as the seat. The world's fastest bicycle is a recumbent bicycle but this type was banned from competition in 1934 by the Union Cycliste Internationale. 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 aluminum alloys are increasingly used in components such as handlebars, seat post, and brake levers. In the 1980s aluminum 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 and even bamboo. Drivetrain and gearing. Since cyclists' legs are most efficient over a narrow range of pedaling speeds (cadence), a variable gear ratio helps a cyclist to maintain an optimum pedalling speed while covering varied terrain. As a first approximation, utility bicycles often use a hub gear with a small number (3 to 5) of widely-spaced gears, road bicycles and racing bicycles use derailleur gears with a moderate number (10 to 22) of closely-spaced gears, while mountain bicycles, hybrid bicycles, and touring bicycles use dérailleur gears with a larger number (15 to 30) of moderately-spaced gears, often including an extremely low gear (granny gear) for climbing steep hills. Different gears and ranges of gears are appropriate for different people and styles of cycling. Multi-speed bicycles allow gear selection to suit the circumstances, e.g. it may be comfortable to use a high gear when cycling downhill, a medium gear when cycling on a flat road, and a low gear when cycling uphill. In a lower gear every turn of the pedals leads to fewer rotations of the rear wheel. This allows the energy required to move the same distance to be distributed over more pedal turns, reducing fatigue when riding uphill, with a heavy load, or against strong winds. A higher gear allows a cyclist to make fewer pedal cycles to maintain a given speed, but with more effort per turn of the pedals. The "drivetrain" begins with pedals which rotate the cranks, which are held in axis by the bottom bracket. Most bicycles use a chain to transmit power to the rear wheel. A relatively small number of bicycles use a shaft drive to transmit power. A very small number of bicycles (mainly single-speed bicycles intended for short-distance commuting) use a belt drive as an oil-free way of transmitting power. With a "chain drive" transmission, a "chainring" attached to a crank drives the chain, which in turn rotates the rear wheel via the rear sprocket(s) (cassette or freewheel). There are four gearing options: two-speed hub gear integrated with chain ring, up to 3 chain rings, up to 11 sprockets, hub gear built in to rear wheel (3-speed to 14-speed). The most common options are either a rear hub or multiple chain rings combined with multiple sprockets (other combinations of options are possible but less common). With a "shaft drive" transmission, a gear set at the bottom bracket turns the shaft, which then turns the rear wheel via a gear set connected to the wheel's hub. There is some small loss of efficiency due to the two gear sets needed. The only gearing option with a shaft drive is to use a hub gear. Steering and seating. The handlebars turn the fork and the front wheel via the stem, which rotates within 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" "drop" as they curve forward and down, offering the cyclist best braking power from a more aerodynamic "crouched" position, as well as more upright positions in which the hands grip the brake lever mounts, the forward curves, or the upper flat sections for increasingly upright postures. Mountain bikes generally feature a 'straight handlebar' or 'riser bar' with varying degrees of sweep backwards and centimeters rise upwards, as well as wider widths which can provide better handling due to increased leverage against the wheel. Saddles also vary with rider preference, from the cushioned ones favored 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, 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 anatomies, although bikes typically are sold with saddles most appropriate for men. A recumbent bicycle has a reclined chair-like 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 steering. Brakes. Modern bicycle "brakes" may be "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, "disc brakes", with a separate rotor for braking. Disc brakes are more common on off-road bicycles, tandems and recumbent bicycles than on road-specific bicycles. 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 dedicated 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, 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, the rider applies resistance to the pedals – this acts as a braking system which can be as effective as a friction-based rear wheel brake, but not as effective as a front wheel brake. Suspension. Bicycle suspension refers to the system or systems used to "suspend" the rider and all or part of the bicycle. This serves two purposes: Bicycle suspensions 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. Suspension is especially important on recumbent bicycles, since while an upright bicycle rider can stand on the pedals to achieve some of the benefits of suspension, a recumbent rider cannot. Wheels. The wheel axle fits into dropouts in the frame and forks. A pair of wheels may be called a wheelset, especially in the context of ready-built "off the shelf", performance-oriented wheels. Tires vary enormously. Skinny, road-racing tires may be completely smooth, or (slick). On the opposite extreme, off-road tires are much wider and thicker, and usually have a deep tread for gripping in muddy conditions. Accessories, repairs, and tools. 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 while preventing clothing from being caught between the chain and crankset teeth. Kick stands keep a bicycle upright when parked. Front-mounted baskets for carrying goods are often used. Luggage carriers and panniers mounted above the rear tire 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 clipless pedals help keep the foot locked in the proper position on the pedals, and enable the cyclist to pull as well as push the pedals—although not without their hazards, eg. may lock foot in when needed to prevent a fall. Technical accessories include cyclocomputers for measuring speed, distance, etc. Other accessories include lights, reflectors, security locks, mirror, water bottles and cages, 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". These may include a tire patch kit (which, in turn, may contain any combination of a hand pump or CO2 Pump, tire levers, spare tubes, self-adhesive patches, or tube-patching material, an adhesive, a piece of sandpaper or a metal grater (to roughing the tube surface to be patched), and sometimes even a block of French chalk.), wrenches, hex keys, screwdrivers, and a chain tool. There are also cycling specific multi-tools that combine many of these implements into a single compact device. More specialized bicycle components may require more complex tools, including proprietary tools specific for a given manufacturer. Some bicycle parts, particularly hub-based gearing systems, are complex, and many cyclists prefer to leave maintenance and repairs to professional bicycle mechanics. In some areas it is possible to purchase road-side assistance from companies such as the Better World Club. Other cyclists maintain their own bicycles, perhaps as part of their enjoyment of the hobby of cycling or simply for economic reasons. The ability to repair and maintain your own bicycle is also celebrated within the DIY movement. Standards. A number of formal and industry standards exist for bicycle components to help make spare parts exchangeable and to maintain a minimum product safety. The International Organization for Standardization, ISO, has a special technical committee for cycles, TC149, that has the following scope: "Standardization in the field of cycles, their components and accessories with particular reference to terminology, testing methods and requirements for performance and safety, and interchangeability." CEN, European Committee for Standardisation, also has a specific Technical Committee, TC333, that defines European standards for cycles. Their mandate states that EN cycle standards shall harmonize with ISO standards. Some CEN cycle standards were developed before ISO published their standards, leading to strong European influences in this area. European cycle standards tend to describe minimum safety requirements, while ISO standards have historically harmonized parts geometry. Parts. For details on specific bicycle parts, see list of bicycle parts and. Social and historical aspects. The bicycle has had a considerable effect on human society, in both the cultural and industrial realms. In daily life. Around the turn of the 20th century, bicycles reduced crowding in inner-city tenements by allowing workers to commute from more spacious dwellings in the suburbs. They also reduced dependence on horses. 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. Recently, several European cities have implemented successful schemes known as community bicycle programs or bike-sharing. These initiatives complement a city's public transport system and offer an alternative to motorized traffic to help reduce congestion and pollution. Users take a bicycle at a parking station, use it for a limited amount of time, and then return it to the same or different station. Examples include Bicing in Barcelona, Vélo'v in Lyon and Vélib' in Paris. In cities where the bicycle is not an integral part of the planned transportation system, commuters often use bicycles as elements of a mixed-mode commute, where the bike is used to travel to and from train stations or other forms of rapid transit. Folding bicycles are useful in these scenarios, as they are less cumbersome when carried aboard. Los Angeles removed a small amount of seating on some trains to make more room for bicycles and wheel chairs. Bicycles offer an important mode of transport in many developing countries. Until recently, bicycles have been a staple of everyday life throughout Asian countries. They are the most frequently used method of transport for commuting to work, school, shopping, and life in general. As a result, bicycles there are almost always equipped with baskets. Female emancipation. 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 symbolize the New Woman of the late 19th century, especially in Britain and the United States. The bicycle was recognized by 19th-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." Male anger at the freedom symbolized by the New (bicycling) Woman was demonstrated when the male undergraduates of Cambridge University showed their opposition to the admission of women as full members of the university by hanging a woman bicyclist in effigy in the main town square. This was as late as 1897. The bicycle craze in the 1890s also 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. 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 aircraft. They also served to teach the industrial models later adopted, including mechanization and mass production (later copied and adopted by Ford and General Motors), vertical integration (also later copied and adopted by Ford), aggressive advertising (as much as 10% of all advertising in U.S. periodicals in 1898 was by bicycle makers), lobbying for better roads (which had the side benefit of acting as advertising, and of improving sales by providing more places to ride), all first practised by Pope. In addition, bicycle makers adopted the annual model change (later derided as planned obsolescence, and usually credited to General Motors), which proved very successful. Furthermore, bicycles were an early example of conspicuous consumption, being adopted by the fashionable elites. In addition, by serving as a platform for accessories, which could ultimately cost more than the bicycle itself, it paved the way for the likes of the Barbie doll. Moreover, they helped create, or enhance, new kinds of businesses, such as bicycle messengers, travelling seamstresses, riding academies, and racing rinks (Their board tracks were later adapted to early motorcycle and automobile racing.) Also, there were a variety of new inventions, such as spoke tighteners, and specialized lights, socks and shoes, and even cameras (such as the Eastman Company's "Poco"). Probably the best known and most widely used of these inventions, adopted well beyond cycling, is Charles Bennett's Bike Web, which came to be called the "jock strap". They also presaged a move away from public transit that would explode with the introduction of the automobile. This liberation would be repeated again with the appearance of the snowmobile. J. K. Starley's company became the Rover Cycle Company Ltd. in the late 1890s, and then simply the Rover Company when it started making cars. The Morris Motor Company (in Oxford) and Škoda also began in the bicycle business, as did the Wright brothers. Alistair Craig, whose company eventually emerged to become the engine manufacturers Ailsa Craig, also started from manufacturing bicycles, in Glasgow in March 1885. In general, U.S. and European cycle manufacturers used to assemble cycles from their own frames and components made by other companies, although very large companies (such as Raleigh) used to make almost every part of a bicycle (including bottom brackets, axles, etc.) In recent years, those bicycle makers have greatly changed their methods of production. Now, almost none of them produce their own frames. Many newer or smaller companies only design and market their products; the actual production is done by Asian companies. For example, some 60% 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 labor in China. One of the profound economic implications of bicycle use is that it liberates the user from oil consumption (Ballantine, 1972). H.G. Wells said: “Every time I see an adult on a bicycle, I no longer despair for the future of the human race.” (Quotegarden.com). The bicycle is a inexpensive, fast, healthy and environmentally friendly mode of transport (Illich, 1974) Legal requirements. Early in its development, like in the case of automobiles, there were restrictions on the operation of bicycles. Along with advertising, and to gain free publicity, Albert A. Pope litigated on behalf of cyclists The 1968 Vienna Convention on Road Traffic of the United Nations considers a bicycle to be a vehicle, and a person controlling a bicycle (whether actually riding or not) is considered an operator. 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 jurisdictions, bicycles must have functioning front and rear lights 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 little noise, some countries insist that bicycles have a warning bell for use when approaching pedestrians, equestrians, and other cyclists. See also. "'Special uses and related vehicle types'" References. Other authors: Eddie Borysewicz, Greg LeMond, Davis Phinney, Connie Carpenter.