The Alcyon was a French bicycle , automobile and motorcycle manufacturer between 1903 and 1954.
113-573: Alcyon originated from about 1890 when Edmond Gentil started the manufacture of bicycles in Neuilly , Seine . In 1902, this was complemented by motorcycle production and in 1906, the first cars were shown at the "Salon de l'Automobile" in Paris, France. Also in 1906 it founded the professional Alcyon cycling team which was active until 1955, including winning the Tour de France 6 times. In 1912 Alcyon competed at
226-446: A phenolic resin . After curing at high temperature in an autoclave , the laminate is pyrolized to convert the resin to carbon, impregnated with furfuryl alcohol in a vacuum chamber, and cured-pyrolized to convert the furfuryl alcohol to carbon. To provide oxidation resistance for reusability, the outer layers of the RCC are converted to silicon carbide . Other examples can be seen in
339-534: A "women's" bicycle, step-through frames are not common for larger frames. Step-throughs were popular partly for practical reasons and partly for social mores of the day. For most of the history of bicycles' popularity women have worn long skirts, and the lower frame accommodated these better than the top-tube. Furthermore, it was considered "unladylike" for women to open their legs to mount and dismount—in more conservative times women who rode bicycles at all were vilified as immoral or immodest. These practices were akin to
452-460: A 'straight handlebar' or 'riser bar' with varying degrees of sweep backward 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, cyclists sit high over
565-469: A Scottish blacksmith, in 1839, although the claim is often disputed. He is also associated with the first recorded instance of a cycling traffic offense, when a Glasgow newspaper in 1842 reported an accident in which an anonymous "gentleman from Dumfries-shire... bestride a velocipede... of ingenious design" knocked over a little girl in Glasgow and was fined five shillings (equivalent to £30 in 2023). In
678-481: A bicycle at low to medium speeds of around 16–24 km/h (10–15 mph) uses only the power required to walk. 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 more aerodynamically streamlined position. Drag can also be reduced by covering
791-496: A bike both stiff and compliant by manipulating the lay-up. Virtually all professional racing bicycles now use carbon fibre frames, as they have the best strength to weight ratio. A typical modern carbon fiber frame can weigh less than 1 kilogram (2.2 lb). Other exotic frame materials include titanium and advanced alloys. Bamboo , a natural composite material with high strength-to-weight ratio and stiffness has been used for bicycles since 1894. Recent versions use bamboo for
904-420: A body of matter or radiation. It states that the behavior of those variables is subject to general constraints common to all materials. These general constraints are expressed in the four laws of thermodynamics. Thermodynamics describes the bulk behavior of the body, not the microscopic behaviors of the very large numbers of its microscopic constituents, such as molecules. The behavior of these microscopic particles
1017-531: A broad range of topics; the following non-exhaustive list highlights a few important research areas. Nanomaterials describe, in principle, materials of which a single unit is sized (in at least one dimension) between 1 and 1000 nanometers (10 meter), but is usually 1 nm – 100 nm. Nanomaterials research takes a materials science based approach to nanotechnology , using advances in materials metrology and synthesis, which have been developed in support of microfabrication research. Materials with structure at
1130-485: A carriage. The design of the bicycle was an advance on the velocipede , although the words were used with some degree of overlap for a time. Other words for bicycle include "bike", "pushbike", "pedal cycle", or "cycle". In Unicode , the code point for "bicycle" is 0x1F6B2. The entity 🚲 in HTML produces 🚲. Although bike and cycle are used interchangeably to refer mostly to two types of two-wheelers,
1243-569: A conventional rear wheel brake, but not as effective as a front wheel brake. Bicycle suspension refers to the system or systems used to suspend the rider and all or part of the bicycle. This serves two purposes: to keep the wheels in continuous contact with the ground, improving control, and to isolate the rider and luggage from jarring due to rough surfaces, improving comfort. Bicycle suspensions are used primarily on mountain bicycles, but are also common on hybrid bicycles, as they can help deal with problematic vibration from poor surfaces. Suspension
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#17328545759601356-496: A cyclist to make fewer pedal turns to maintain a given speed, but with more effort per turn of the pedals. 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 12 sprockets, hub gear built into rear wheel (3-speed to 14-speed). The most common options are either
1469-412: A design bought from SIMA-Violet . Later the company manufactured another cyclecar of similar design, thought this one featured a single-cylinder engine. This proved a complete flop, and the company failed in 1928. Alcyon never sold cars again. In 1946, the "Gentil Trophy" was created in memory of the founder of Cycles Alcyon, who died that year. It was awarded for the "achievement of the year", and took
1582-445: A drug over an extended period of time. A biomaterial may also be an autograft , allograft or xenograft used as an organ transplant material. Semiconductors, metals, and ceramics are used today to form highly complex systems, such as integrated electronic circuits, optoelectronic devices, and magnetic and optical mass storage media. These materials form the basis of our modern computing world, and hence research into these materials
1695-472: A few. The basis of materials science is studying the interplay between the structure of materials, the processing methods to make that material, and the resulting material properties. The complex combination of these produce the performance of a material in a specific application. Many features across many length scales impact material performance, from the constituent chemical elements, its microstructure , and macroscopic features from processing. Together with
1808-399: 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
1921-776: A large number of identical components linked together like chains. Polymers are the raw materials (the resins) used to make what are commonly called plastics and rubber . Plastics and rubber are the final product, created after one or more polymers or additives have been added to a resin during processing, which is then shaped into a final form. Plastics in former and in current widespread use include polyethylene , polypropylene , polyvinyl chloride (PVC), polystyrene , nylons , polyesters , acrylics , polyurethanes , and polycarbonates . Rubbers include natural rubber, styrene-butadiene rubber, chloroprene , and butadiene rubber . Plastics are generally classified as commodity , specialty and engineering plastics . Polyvinyl chloride (PVC)
2034-437: A metal oxide fused with silica. At the high temperatures used to prepare glass, the material is a viscous liquid which solidifies into a disordered state upon cooling. Windowpanes and eyeglasses are important examples. Fibers of glass are also used for long-range telecommunication and optical transmission. Scratch resistant Corning Gorilla Glass is a well-known example of the application of materials science to drastically improve
2147-465: A narrow range of pedaling speeds, or cadence , a variable gear ratio helps a cyclist to maintain an optimum pedalling speed while covering varied terrain. Some, mainly utility, bicycles use hub gears with between 3 and 14 ratios, but most use the generally more efficient dérailleur system, by which the chain is moved between different cogs called chainrings and sprockets to select a ratio. A dérailleur system normally has two dérailleurs, or mechs, one at
2260-418: A natural function. Such functions may be benign, like being used for a heart valve , or may be bioactive with a more interactive functionality such as hydroxylapatite -coated hip implants . Biomaterials are also used every day in dental applications, surgery, and drug delivery. For example, a construct with impregnated pharmaceutical products can be placed into the body, which permits the prolonged release of
2373-441: A popular form of recreation , and have been adapted for use as children's toys . Bicycles are used for fitness , military and police applications, courier services , bicycle racing , and artistic cycling . The basic shape and configuration of a typical upright or "safety" bicycle , has changed little since the first chain-driven model was developed around 1885. However, many details have been improved, especially since
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#17328545759602486-865: A proliferation of specialized bicycle types, improved bicycle safety , and riding comfort. Bicycles can be categorized in many different ways: 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 bikes . Less common are tandems , low riders , tall bikes , fixed gear , folding models , amphibious bicycles , cargo bikes , recumbents and electric bicycles . 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" or "cycles". A bicycle stays upright while moving forward by being steered so as to keep its center of mass over
2599-486: A rear hub or multiple chain rings combined with multiple sprockets (other combinations of options are possible but less common). The handlebars connect to the stem that connects to the fork that connects to the front wheel, and the whole assembly connects to the bike and rotates about the steering axis via the headset bearings. Three styles of handlebar are common. Upright handlebars , the norm in Europe and elsewhere until
2712-560: A sales agent of the Coventry Sewing Machine Company (which soon became the Coventry Machinists Company ), brought a Michaux cycle to Coventry , England. His uncle, Josiah Turner, and business partner James Starley , used this as a basis for the 'Coventry Model' in what became Britain's first cycle factory. The dwarf ordinary addressed some of these faults by reducing the front wheel diameter and setting
2825-618: 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. By the 1980s aluminum welding techniques had improved to the point that aluminum tube could safely be used in place of steel . Since then aluminum alloy frames and other components have become popular due to their light weight, and most mid-range bikes are now principally aluminum alloy of some kind. More expensive bikes use carbon fibre due to its significantly lighter weight and profiling ability, allowing designers to make
2938-876: A single crystal, but in polycrystalline form, as an aggregate of small crystals or grains with different orientations. Because of this, the powder diffraction method , which uses diffraction patterns of polycrystalline samples with a large number of crystals, plays an important role in structural determination. Most materials have a crystalline structure, but some important materials do not exhibit regular crystal structure. Polymers display varying degrees of crystallinity, and many are completely non-crystalline. Glass , some ceramics, and many natural materials are amorphous , not possessing any long-range order in their atomic arrangements. The study of polymers combines elements of chemical and statistical thermodynamics to give thermodynamic and mechanical descriptions of physical properties. Materials, which atoms and molecules form constituents in
3051-521: A two-seat light car with single-cylinder 950 cc engine and a larger four seat model with 1.4-litre four-cylinder engine. Both engines were bought in from Gentil. The cars were advanced models with 3-speed gearboxes and shaft drive. However, the single-cylinder models were dropped in 1912 and larger models of up to 2120 cc were added to the range. By then, most of the engines were obtained from Zurcher . The company moved to Courbevoie , Seine in 1912. In 1954 Peugeot absorbed Alcyon. In 1914,
3164-511: A wheelset, especially in the context of ready-built "off the shelf", performance-oriented wheels. Tires vary enormously depending on their intended purpose. Road bicycles use tires 18 to 25 millimeters wide, most often completely smooth, or slick , and inflated to high pressure to roll fast on smooth surfaces. Off-road tires are usually between 38 and 64 mm (1.5 and 2.5 in) wide, and have treads for gripping in muddy conditions or metal studs for ice. Groupset generally refers to all of
3277-509: Is a human-powered or motor-assisted , pedal-driven , single-track vehicle , with two wheels attached to a frame , one behind the other. A bicycle rider is called a cyclist, or bicyclist. Bicycles were introduced in the 19th century in Europe . By the early 21st century there were more than 1 billion bicycles. There are many more bicycles than cars . Bicycles are the principal means of transport in many regions. They also provide
3390-443: Is an engineering plastic which is used extensively as the glide rails for industrial equipment and the low-friction socket in implanted hip joints . The alloys of iron ( steel , stainless steel , cast iron , tool steel , alloy steels ) make up the largest proportion of metals today both by quantity and commercial value. Iron alloyed with various proportions of carbon gives low , mid and high carbon steels . An iron-carbon alloy
3503-519: Is any matter, surface, or construct that interacts with biological systems . Biomaterials science encompasses elements of medicine, biology, chemistry, tissue engineering, and materials science. Biomaterials can be derived either from nature or synthesized in a laboratory using a variety of chemical approaches using metallic components, polymers , bioceramics , or composite materials . They are often intended or adapted for medical applications, such as biomedical devices which perform, augment, or replace
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3616-498: Is applied to brake levers mounted on the handlebars and transmitted via Bowden cables or hydraulic lines to the friction pads, which apply pressure to the braking surface, causing friction which slows the bicycle down. 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. Track bicycles do not have brakes, because all riders ride in
3729-432: Is based on the empirical makeup and atomic structure of the solid materials, and most solids fall into one of these broad categories. An item that is often made from each of these materials types is the beverage container. The material types used for beverage containers accordingly provide different advantages and disadvantages, depending on the material used. Ceramic (glass) containers are optically transparent, impervious to
3842-507: Is called the materials paradigm. This paradigm is used for advanced understanding in a variety of research areas, including nanotechnology , biomaterials , and metallurgy . Materials science is also an important part of forensic engineering and failure analysis – investigating materials, products, structures or their components, which fail or do not function as intended, causing personal injury or damage to property. Such investigations are key to understanding. For example,
3955-465: Is derived from cemented carbides with the metal phase of cobalt and nickel typically added to modify properties. Ceramics can be significantly strengthened for engineering applications using the principle of crack deflection . This process involves the strategic addition of second-phase particles within a ceramic matrix, optimizing their shape, size, and distribution to direct and control crack propagation. This approach enhances fracture toughness, paving
4068-438: Is described by, and the laws of thermodynamics are derived from, statistical mechanics . The study of thermodynamics is fundamental to materials science. It forms the foundation to treat general phenomena in materials science and engineering, including chemical reactions, magnetism, polarizability, and elasticity. It explains fundamental tools such as phase diagrams and concepts such as phase equilibrium . Chemical kinetics
4181-445: 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. Basic mountain bicycles and hybrids usually have front suspension only, whilst more sophisticated ones also have rear suspension. Road bicycles tend to have no suspension. The wheel axle fits into fork ends in the frame and fork. A pair of wheels may be called
4294-479: Is important in the study of kinetics as this is the most common mechanism by which materials undergo change. Kinetics is essential in processing of materials because, among other things, it details how the microstructure changes with application of heat. Materials science is a highly active area of research. Together with materials science departments, physics , chemistry , and many engineering departments are involved in materials research. Materials research covers
4407-441: Is necessary to differentiate between the number of dimensions on the nanoscale . Nanotextured surfaces have one dimension on the nanoscale, i.e., only the thickness of the surface of an object is between 0.1 and 100 nm. Nanotubes have two dimensions on the nanoscale, i.e., the diameter of the tube is between 0.1 and 100 nm; its length could be much greater. Finally, spherical nanoparticles have three dimensions on
4520-402: Is of vital importance. Semiconductors are a traditional example of these types of materials. They are materials that have properties that are intermediate between conductors and insulators . Their electrical conductivities are very sensitive to the concentration of impurities, which allows the use of doping to achieve desirable electronic properties. Hence, semiconductors form the basis of
4633-494: Is only considered steel if the carbon level is between 0.01% and 2.00% by weight. For steels, the hardness and tensile strength of the steel is related to the amount of carbon present, with increasing carbon levels also leading to lower ductility and toughness. Heat treatment processes such as quenching and tempering can significantly change these properties, however. In contrast, certain metal alloys exhibit unique properties where their size and density remain unchanged across
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4746-407: Is studied in the following levels. Atomic structure deals with the atoms of the material, and how they are arranged to give rise to molecules, crystals, etc. Much of the electrical, magnetic and chemical properties of materials arise from this level of structure. The length scales involved are in angstroms ( Å ). The chemical bonding and atomic arrangement (crystallography) are fundamental to studying
4859-471: Is the most efficient human-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 an efficient means of cargo transportation. A human traveling on
4972-417: Is the study of the rates at which systems that are out of equilibrium change under the influence of various forces. When applied to materials science, it deals with how a material changes with time (moves from non-equilibrium state to equilibrium state) due to application of a certain field. It details the rate of various processes evolving in materials including shape, size, composition and structure. Diffusion
5085-514: Is used to protect the surface of the shuttle from the heat of re-entry into the Earth's atmosphere. One example is reinforced Carbon-Carbon (RCC), the light gray material, which withstands re-entry temperatures up to 1,510 °C (2,750 °F) and protects the Space Shuttle's wing leading edges and nose cap. RCC is a laminated composite material made from graphite rayon cloth and impregnated with
5198-436: Is widely used, inexpensive, and annual production quantities are large. It lends itself to a vast array of applications, from artificial leather to electrical insulation and cabling, packaging , and containers . Its fabrication and processing are simple and well-established. The versatility of PVC is due to the wide range of plasticisers and other additives that it accepts. The term "additives" in polymer science refers to
5311-469: The Age of Enlightenment , when researchers began to use analytical thinking from chemistry , physics , maths and engineering to understand ancient, phenomenological observations in metallurgy and mineralogy . Materials science still incorporates elements of physics, chemistry, and engineering. As such, the field was long considered by academic institutions as a sub-field of these related fields. Beginning in
5424-634: The Bronze Age and Iron Age and is studied under the branch of materials science named physical metallurgy . Chemical and physical methods are also used to synthesize other materials such as polymers , ceramics , semiconductors , and thin films . As of the early 21st century, new methods are being developed to synthesize nanomaterials such as graphene . Thermodynamics is concerned with heat and temperature , and their relation to energy and work . It defines macroscopic variables, such as internal energy , entropy , and pressure , that partly describe
5537-590: The Giro d'Italia , the Tour de France , the Vuelta a España , the Tour de Pologne , and the Volta a Portugal . They are also used for entertainment and pleasure in other ways, such as in organised mass rides, artistic cycling and freestyle BMX . 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
5650-933: The Honda Super Cub motorcycle, has more than 100 million units made, while most produced car, the Toyota Corolla , has reached 44 million and counting. Bicycles are used for transportation, bicycle commuting , and utility cycling . They are also used professionally by mail carriers , paramedics , police , messengers , and general delivery services. Military uses of bicycles include communications , reconnaissance , troop movement, supply of provisions, and patrol, such as in bicycle infantries . They are also used for recreational purposes, including bicycle touring , mountain biking , physical fitness , and play . Bicycle sports include racing , BMX racing , track racing , criterium , roller racing , sportives and time trials . Major multi-stage professional events are
5763-578: The Isle of Man TT races with a 348cc single-cylinder engine featuring two inlet valves and two exhaust valves. Both bikes failed to finish the Junior TT race. Alcyon had local success in France during the 1920s, with riders such as Marc Jolly, Marcel Mourrier, Jean Durand and Lucien Lemasson winning races. During this time too, this bicycle brand got its nickname "l'intrépide Alcyon". Two models were shown in 1906, one
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#17328545759605876-497: The World Fair and was produced in a few thousand units. In the 1870s many cycling clubs flourished. They were popular in a time when there were no cars on the market and the principal mode of transportation was horse-drawn vehicles , such the horse and buggy or the horsecar . Among the earliest clubs was The Bicycle Touring Club , which has operated since 1878. By the turn of the century, cycling clubs flourished on both sides of
5989-407: The seat further back. This, in turn, required gearing—effected in a variety of ways—to efficiently use pedal power. Having to both pedal and steer via the front wheel remained a problem. Englishman J.K. Starley (nephew of James Starley), J.H. Lawson, and Shergold solved this problem by introducing the chain drive (originated by the unsuccessful "bicyclette" of Englishman Henry Lawson), connecting
6102-517: The seat tube was added which created the modern bike's double-triangle diamond frame . 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 first practical pneumatic tire, which soon became universal. Willie Hume demonstrated the supremacy of Dunlop's tyres in 1889, winning the tyre's first-ever races in Ireland and then England. Soon after,
6215-495: The "plastic" casings of television sets, cell-phones and so on. These plastic casings are usually a composite material made up of a thermoplastic matrix such as acrylonitrile butadiene styrene (ABS) in which calcium carbonate chalk, talc , glass fibers or carbon fibers have been added for added strength, bulk, or electrostatic dispersion . These additions may be termed reinforcing fibers, or dispersants, depending on their purpose. Polymers are chemical compounds made up of
6328-449: The 1940s, materials science began to be more widely recognized as a specific and distinct field of science and engineering, and major technical universities around the world dedicated schools for its study. Materials scientists emphasize understanding how the history of a material ( processing ) influences its structure, and also the material's properties and performance. The understanding of processing structure properties relationships
6441-443: 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
6554-509: The Atlantic, and touring and racing became widely popular. The Raleigh Bicycle Company was founded in Nottingham, England in 1888. It became the biggest bicycle manufacturing company in the world, making over two million bikes per year. 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
6667-569: The United States was catalyzed in part by the Advanced Research Projects Agency , which funded a series of university-hosted laboratories in the early 1960s, " to expand the national program of basic research and training in the materials sciences ." In comparison with mechanical engineering, the nascent materials science field focused on addressing materials from the macro-level and on the approach that materials are designed on
6780-414: The advent of modern materials and computer-aided design . These have allowed for a proliferation of specialized designs for many types of cycling. In the 21st century, electric bicycles have become popular. The bicycle's invention has had an enormous effect on society, both in terms of culture and of advancing modern industrial methods. Several components that played a key role in the development of
6893-436: The atomic scale, all the way up to the macro scale. Characterization is the way materials scientists examine the structure of a material. This involves methods such as diffraction with X-rays , electrons or neutrons , and various forms of spectroscopy and chemical analysis such as Raman spectroscopy , energy-dispersive spectroscopy , chromatography , thermal analysis , electron microscope analysis, etc. Structure
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#17328545759607006-551: The automobile were initially invented for use in the bicycle, including ball bearings , pneumatic tires , chain-driven sprockets , and tension-spoked wheels . The word bicycle first appeared in English print in The Daily News in 1868, to describe "Bysicles and trysicles" on the "Champs Elysées and Bois de Boulogne". The word was first used in 1847 in a French publication to describe an unidentified two-wheeled vehicle, possibly
7119-584: The basis of knowledge of behavior at the microscopic level. Due to the expanded knowledge of the link between atomic and molecular processes as well as the overall properties of materials, the design of materials came to be based on specific desired properties. The materials science field has since broadened to include every class of materials, including ceramics, polymers , semiconductors, magnetic materials, biomaterials, and nanomaterials , generally classified into three distinct groups- ceramics, metals, and polymers. The prominent change in materials science during
7232-577: The best known being the rod-driven velocipede by Scotsman Thomas McCall in 1869. In that same year, bicycle wheels with wire spokes were patented by Eugène Meyer of Paris. The French vélocipède , made of iron and wood, developed into the " penny-farthing " (historically known as an "ordinary bicycle", a retronym , since there was 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 high seat and poor weight distribution . In 1868 Rowley Turner,
7345-447: The bicycle with an aerodynamic fairing . The fastest recorded unpaced speed on a flat surface is 144.18 km/h (89.59 mph). 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 ⁄ 10 that generated by energy efficient motorcars. The great majority of modern bicycles have a frame with upright seating that looks much like
7458-405: The bicycle. Short-wheelbase or tall bicycles, when braking, can generate enough stopping force at the front wheel 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. The bicycle is extraordinarily efficient in both biological and mechanical terms. The bicycle
7571-496: The causes of various aviation accidents and incidents . The material of choice of a given era is often a defining point. Phases such as Stone Age , Bronze Age , Iron Age , and Steel Age are historic, if arbitrary examples. Originally deriving from the manufacture of ceramics and its putative derivative metallurgy, materials science is one of the oldest forms of engineering and applied sciences. Modern materials science evolved directly from metallurgy , which itself evolved from
7684-569: The chemicals and compounds added to the polymer base to modify its material properties. Polycarbonate would be normally considered an engineering plastic (other examples include PEEK , ABS). Such plastics are valued for their superior strengths and other special material properties. They are usually not used for disposable applications, unlike commodity plastics. Specialty plastics are materials with unique characteristics, such as ultra-high strength, electrical conductivity, electro-fluorescence, high thermal stability, etc. The dividing lines between
7797-466: The company's name was changed to Automobiles Alcyon . After the war, the first model was a 1914 cc four-cylinder model, some examples of which were tuned and sold by the Lyons agent as Alycon-GLs and performed quite well in competition. However, the car was not a success and did not sell well, so in 1923, Alcyon moved into the production of cyclecars , using 500 cc two-stroke flat-twin engines in
7910-448: The components that make up a bicycle excluding the bicycle frame, fork, stem, wheels, tires, and rider contact points, such as the saddle and handlebars. Modern materials Materials science is an interdisciplinary field of researching and discovering materials . Materials engineering is an engineering field of finding uses for materials in other fields and industries. The intellectual origins of materials science stem from
8023-436: The desired micro-nanostructure. A material cannot be used in industry if no economically viable production method for it has been developed. Therefore, developing processing methods for materials that are reasonably effective and cost-efficient is vital to the field of materials science. Different materials require different processing or synthesis methods. For example, the processing of metals has historically defined eras such as
8136-413: 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 (the velocipede ). This was the first in mass production. Another French inventor named Douglas Grasso had a failed prototype of Pierre Lallement's bicycle several years earlier. Several inventions followed using rear-wheel drive,
8249-658: The effects of the crystalline arrangement of atoms is often easy to see macroscopically, because the natural shapes of crystals reflect the atomic structure. Further, physical properties are often controlled by crystalline defects. The understanding of crystal structures is an important prerequisite for understanding crystallographic defects . Examples of crystal defects consist of dislocations including edges, screws, vacancies, self interstitials, and more that are linear, planar, and three dimensional types of defects. New and advanced materials that are being developed include nanomaterials , biomaterials . Mostly, materials do not occur as
8362-456: The exploration of space. Materials science has driven, and been driven by the development of revolutionary technologies such as rubbers , plastics , semiconductors , and biomaterials . Before the 1960s (and in some cases decades after), many eventual materials science departments were metallurgy or ceramics engineering departments, reflecting the 19th and early 20th-century emphasis on metals and ceramics. The growth of material science in
8475-446: The final properties of the materials produced. For example, steels are classified based on 1/10 and 1/100 weight percentages of the carbon and other alloying elements they contain. Thus, the extracting and purifying methods used to extract iron in a blast furnace can affect the quality of steel that is produced. Solid materials are generally grouped into three basic classifications: ceramics, metals, and polymers. This broad classification
8588-406: The first chain-driven bike. These 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
8701-466: The form of a work of art created by Carlo Sarrabezolles . Each National Federation expressed its choice and the winner had to obtain 70% of the votes to obtain this honorary title. The company also gave its name to a race, the Grand critérium Alcyon, open to independent and aspiring riders under U.V.F. regulations. Bicycles A bicycle , also called a pedal cycle , bike , push-bike or cycle ,
8814-491: The frame-mounted cranks to the rear wheel. These models were known as safety bicycles , dwarf safeties, or upright bicycles for their lower seat height and better weight distribution, although without pneumatic tires the ride of the smaller-wheeled bicycle would be much rougher than that of the larger-wheeled variety. Starley's 1885 Rover , manufactured in Coventry is usually described as the first recognizably modern bicycle. Soon
8927-446: The front to select the chainring and another at the back to select the sprocket. Most bikes have two or three chainrings, and from 5 to 11 sprockets on the back, with the number of theoretical gears calculated by multiplying front by back. In reality, many gears overlap or require the chain to run diagonally, so the number of usable gears is fewer. An alternative to chaindrive is to use a synchronous belt. These are toothed and work much
9040-410: 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 dropout , where the axle for the rear wheel is held. The seat stays connect the top of the seat tube (at or near the same point as
9153-421: The laws of thermodynamics and kinetics materials scientists aim to understand and improve materials. Structure is one of the most important components of the field of materials science. The very definition of the field holds that it is concerned with the investigation of "the relationships that exist between the structures and properties of materials". Materials science examines the structure of materials from
9266-399: The material properties. Macrostructure is the appearance of a material in the scale millimeters to meters, it is the structure of the material as seen with the naked eye. Materials exhibit myriad properties, including the following. The properties of a material determine its usability and hence its engineering application. Synthesis and processing involves the creation of a material with
9379-411: The material scientist or engineer also deals with extracting materials and converting them into useful forms. Thus ingot casting, foundry methods, blast furnace extraction, and electrolytic extraction are all part of the required knowledge of a materials engineer. Often the presence, absence, or variation of minute quantities of secondary elements and compounds in a bulk material will greatly affect
9492-402: The mechanism is contained within the wheel hub, or disc brakes, where pads act on a rotor attached to the hub. Most road bicycles use rim brakes, but some use disc brakes. Disc brakes are more common for mountain bikes, tandems and recumbent bicycles than on other types of bicycles, due to their increased power, coupled with an increased weight and complexity. With hand-operated brakes, force
9605-500: The nanoscale (i.e., they form nanostructures) are called nanomaterials. Nanomaterials are the subject of intense research in the materials science community due to the unique properties that they exhibit. Nanostructure deals with objects and structures that are in the 1 – 100 nm range. In many materials, atoms or molecules agglomerate to form objects at the nanoscale. This causes many interesting electrical, magnetic, optical, and mechanical properties. In describing nanostructures, it
9718-404: The nanoscale often have unique optical, electronic, or mechanical properties. The field of nanomaterials is loosely organized, like the traditional field of chemistry, into organic (carbon-based) nanomaterials, such as fullerenes, and inorganic nanomaterials based on other elements, such as silicon. Examples of nanomaterials include fullerenes , carbon nanotubes , nanocrystals, etc. A biomaterial
9831-400: The nanoscale, i.e., the particle is between 0.1 and 100 nm in each spatial dimension. The terms nanoparticles and ultrafine particles (UFP) often are used synonymously although UFP can reach into the micrometre range. The term 'nanostructure' is often used, when referring to magnetic technology. Nanoscale structure in biology is often called ultrastructure . Microstructure is defined as
9944-531: The older practice of riding horse sidesaddle . 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
10057-424: The overall weight of the bicycle. 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 . Bicycle brakes may be rim brakes, in which friction pads are compressed against the wheel rims; hub brakes, where
10170-471: The passage of carbon dioxide as aluminum and glass. Another application of materials science is the study of ceramics and glasses , typically the most brittle materials with industrial relevance. Many ceramics and glasses exhibit covalent or ionic-covalent bonding with SiO 2 ( silica ) as a fundamental building block. Ceramics – not to be confused with raw, unfired clay – are usually seen in crystalline form. The vast majority of commercial glasses contain
10283-501: The passage of carbon dioxide, relatively inexpensive, and are easily recycled, but are also heavy and fracture easily. Metal (aluminum alloy) is relatively strong, is a good barrier to the diffusion of carbon dioxide, and is easily recycled. However, the cans are opaque, expensive to produce, and are easily dented and punctured. Polymers (polyethylene plastic) are relatively strong, can be optically transparent, are inexpensive and lightweight, and can be recyclable, but are not as impervious to
10396-490: The primary frame with glued metal connections and parts, priced as exotic models. 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 very small number of bicycles use a shaft drive to transmit power, or special belts. Hydraulic bicycle transmissions have been built, but they are currently inefficient and complex. Since cyclists' legs are most efficient over
10509-429: The properties and behavior of any material. To obtain a full understanding of the material structure and how it relates to its properties, the materials scientist must study how the different atoms, ions and molecules are arranged and bonded to each other. This involves the study and use of quantum chemistry or quantum physics . Solid-state physics , solid-state chemistry and physical chemistry are also involved in
10622-512: The properties of common components. Engineering ceramics are known for their stiffness and stability under high temperatures, compression and electrical stress. Alumina, silicon carbide , and tungsten carbide are made from a fine powder of their constituents in a process of sintering with a binder. Hot pressing provides higher density material. Chemical vapor deposition can place a film of a ceramic on another material. Cermets are ceramic particles containing some metals. The wear resistance of tools
10735-525: The rear freewheel was developed, enabling the rider to coast. This refinement led to the 1890s invention of coaster brakes . Dérailleur gears and hand-operated Bowden cable -pull brakes were also developed during these years, but were only slowly adopted by casual riders. The Svea Velocipede with vertical pedal arrangement and locking hubs was introduced in 1892 by the Swedish engineers Fredrik Ljungström and Birger Ljungström . It attracted attention at
10848-498: The recent decades is active usage of computer simulations to find new materials, predict properties and understand phenomena. A material is defined as a substance (most often a solid, but other condensed phases can also be included) that is intended to be used for certain applications. There are a myriad of materials around us; they can be found in anything from new and advanced materials that are being developed include nanomaterials , biomaterials , and energy materials to name
10961-466: 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 laterally into two thinner top tubes that bypass the seat tube on each side and connect to the rear fork ends. The ease of stepping through is also appreciated by those with limited flexibility or other joint problems. Because of its persistent image as
11074-402: The same as a chain—popular with commuters and long distance cyclists they require little maintenance. They cannot be shifted across a cassette of sprockets, and are used either as single speed or with a hub gear. 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: a cyclist could use
11187-416: 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 cranks are moving. To slow down, the rider applies resistance to the pedals, acting as a braking system which can be as effective as
11300-604: 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 and sit bone width measurements, although bikes typically are sold with saddles most appropriate for men. Suspension seat posts and seat springs provide comfort by absorbing shock but can add to
11413-463: The structure of a prepared surface or thin foil of material as revealed by a microscope above 25× magnification. It deals with objects from 100 nm to a few cm. The microstructure of a material (which can be broadly classified into metallic, polymeric, ceramic and composite) can strongly influence physical properties such as strength, toughness, ductility, hardness, corrosion resistance, high/low temperature behavior, wear resistance, and so on. Most of
11526-526: The study of bonding and structures. Crystallography is the science that examines the arrangement of atoms in crystalline solids. Crystallography is a useful tool for materials scientists. One of the fundamental concepts regarding the crystal structure of a material includes the unit cell , which is the smallest unit of a crystal lattice (space lattice) that repeats to make up the macroscopic crystal structure. Most common structural materials include parallelpiped and hexagonal lattice types. In single crystals ,
11639-456: The terms still vary across the world. In India, for example, a cycle refers only to a two-wheeler using pedal power whereas the term bike is used to describe a two-wheeler using internal combustion engine or electric motors as a source of motive power instead of motorcycle/motorbike. The " dandy horse ", also called Draisienne or Laufmaschine ("running machine"), was the first human means of transport to use only two wheels in tandem and
11752-1091: The time and effort to optimize materials properties for a given application. This involves simulating materials at all length scales, using methods such as density functional theory , molecular dynamics , Monte Carlo , dislocation dynamics, phase field , finite element , and many more. Radical materials advances can drive the creation of new products or even new industries, but stable industries also employ materials scientists to make incremental improvements and troubleshoot issues with currently used materials. Industrial applications of materials science include materials design, cost-benefit tradeoffs in industrial production of materials, processing methods ( casting , rolling , welding , ion implantation , crystal growth , thin-film deposition , sintering , glassblowing , etc.), and analytic methods (characterization methods such as electron microscopy , X-ray diffraction , calorimetry , nuclear microscopy (HEFIB) , Rutherford backscattering , neutron diffraction , small-angle X-ray scattering (SAXS), etc.). Besides material characterization,
11865-446: The top tube) to the rear fork ends. 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 or as an open frame , allows
11978-686: The traditional computer. This field also includes new areas of research such as superconducting materials, spintronics , metamaterials , etc. The study of these materials involves knowledge of materials science and solid-state physics or condensed matter physics . With continuing increases in computing power, simulating the behavior of materials has become possible. This enables materials scientists to understand behavior and mechanisms, design new materials, and explain properties formerly poorly understood. Efforts surrounding integrated computational materials engineering are now focusing on combining computational methods with experiments to drastically reduce
12091-510: The traditional materials (such as metals and ceramics) are microstructured. The manufacture of a perfect crystal of a material is physically impossible. For example, any crystalline material will contain defects such as precipitates , grain boundaries ( Hall–Petch relationship ), vacancies, interstitial atoms or substitutional atoms. The microstructure of materials reveals these larger defects and advances in simulation have allowed an increased understanding of how defects can be used to enhance
12204-632: The use of fire. A major breakthrough in the understanding of materials occurred in the late 19th century, when the American scientist Josiah Willard Gibbs demonstrated that the thermodynamic properties related to atomic structure in various phases are related to the physical properties of a material. Important elements of modern materials science were products of the Space Race ; the understanding and engineering of metallic alloys , and silica and carbon materials, used in building space vehicles enabling
12317-439: The various types of plastics is not based on material but rather on their properties and applications. For example, polyethylene (PE) is a cheap, low friction polymer commonly used to make disposable bags for shopping and trash, and is considered a commodity plastic, whereas medium-density polyethylene (MDPE) is used for underground gas and water pipes, and another variety called ultra-high-molecular-weight polyethylene (UHMWPE)
12430-505: The way for the creation of advanced, high-performance ceramics in various industries. Another application of materials science in industry is making composite materials . These are structured materials composed of two or more macroscopic phases. Applications range from structural elements such as steel-reinforced concrete, to the thermal insulating tiles, which play a key and integral role in NASA's Space Shuttle thermal protection system , which
12543-407: 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 to 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
12656-630: Was invented by the German Baron Karl von Drais . It is regarded as the first bicycle and von Drais is seen as the "father of the bicycle", but it did not have pedals. Von Drais introduced it to the public in Mannheim in 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 or her feet while steering the front wheel. The first mechanically propelled, two-wheeled vehicle may have been built by Kirkpatrick MacMillan ,
12769-505: Was stimulated by the widespread advertising, production, and use of these devices. More than 1 billion bicycles have been manufactured worldwide as of the early 21st century. Bicycles are the most common vehicle of any kind in the world, and the most numerous model of any kind of vehicle, whether human-powered or motor vehicle , is the Chinese Flying Pigeon , with numbers exceeding 500 million. The next most numerous vehicle,
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