Motorcycle
From Wikipedia, the free encyclopedia
A motorcycle is any two-wheeled vehicle powered by an engine. Motorcycles are one of the cheapest and most widespread forms of motorised transport in many parts of the world.
On a typical motorcycle, the operator sits astride the vehicle on a seat, with the hands on a set of handlebars and the feet supported by footpegs. When the bike is at rest, the rider puts one or both feet on the ground. Engine speed is controlled by twisting the throttle on the right handlebar grip with braking being controlled with a hand lever and foot pedal. Shifting of gear ratios is controlled by operating a foot lever with the clutch being operated by a hand lever. Steering is accomplished by leaning the bike and moving the handlebars.
Contents |
[edit] History
The inspiration for the earliest dirt bike, and arguably the first motorcycle, was designed and built by the German inventors Gottlieb Daimler and Wilhelm Maybach in Bad Cannstatt (since 1905 a city district of Stuttgart) in 1885. The first petroleum-powered vehicle, it was essentially a motorized bicycle, although the inventors called their invention the Reitwagen ("riding car"). They had not set out to create a vehicle form but to build a simple carriage for the engine, which was the focus of their endeavours.
However, if one counts two wheels with steam propulsion as being a motorcycle, then the first one may have been American. One such machine was demonstrated at fairs and circuses in the eastern US in 1867, built by Sylvester Howard Roper of Roxbury, Massachusetts. There is an existing example of a Roper machine dated 1869. But there is no patent existing and nothing proves it was working. It's powered by a charcoal-fired two-cylinder engine, whose connecting rods directly drive a crank on the rear wheel. This machine predates the invention of the safety bicycle by many years, so its chassis is also based on the "boneshaker" bike. In 1868, the French engineer Louis-Guillaume Perreaux patented a similar steam-powered motorcycle, probably invented independent of Roper. In his case a patent exists (dated 1868), but nothing indicates his invention had moved before 1871.
In 1894, the Hildebrand & Wolfmüller became the first motorcycle available for purchase.
In the early period of motorcycle history there were many manufacturers as producers of bicycles adapted their designs for the new internal combustion engine. As the engines became more powerful and designs outgrew the bicycle origins, the number of motorcycle producers increased.
Until the First World War, the largest motorcycle manufacturer was Indian. After that, this honour went to Harley-Davidson, until 1928 when DKW took over as the largest manufacturer. BMW motorcycles came on the scene in 1923 with shaft drive and an opposed-twin or "boxer" engine enclosed with the transmission in a single aluminum housing (photo right).
After the Second World War, the BSA Group purchased Triumph Motorcycles in 1951 to become the largest producer of motorcycles in the world claiming "one in four". The German NSU was the largest manufacturer from 1955 until the 1970s when Honda became the largest manufacturer -- a title it holds to this day. British manufacturers (Triumph, BSA, Norton) retained a dominant position in some markets until the rise of the Japanese manufacturers (led by Honda) in the late 1960s and early 1970s, who were able to produce designs more quickly, more cheaply, and of better quality than their competitors. The British manufacturers became defunct as mass-market producers.
Today the Japanese manufacturers, Honda, Kawasaki, Suzuki, and Yamaha dominate the motorcycle industry, although Harley-Davidson still maintains a high degree of popularity in the United States. Recent years have also seen a resurgence in the popularity of many other brands including BMW, Triumph and Ducati, and the emergence of Victory as a second successful mass-builder of big-twin American cruisers.
[edit] Technical Aspects
[edit] Construction
The construction of modern motorcycles has mostly standardized on the following key components.
[edit] Chassis
The chassis (or frame) of a motorcycle is typically made from welded aluminium or steel (or an alloy) struts, with the rear suspension being an integral component in the design. Carbon-fiber and titanium are used in a few very expensive custom frames.
Some motorcycles include the engine as a load-bearing (or stressed) member; this has been used all through bike history but is now becoming more common.
Oil-in-Frame (OIF) chassis, where the lubricating oil is stored in the frame of the motorcycle, was used for Vincent motorcycles of the fifties, and for a while during the 1970s on some NVT British motorcycles. It was widely unpopular and generally regarded as a bad idea at the time. Today it is a widely used idea on "thumpers" (single-cylinder four-strokes) that usually have a dry-sump lubrication requiring an external oil tank. It has since gained some cache in modern (2006) custom bike world too because of the space saving it can afford and the reference to an earlier era. [1]. Buell motorcycles employ a similar design - the oil is held in the swingarm, while the fuel to power the motorcycle is held in the frame.
[edit] Front fork
A motorcycle fork is the portion of a motorcycle that holds the front wheel and allows one to steer. For handling, the front fork is the most critical part of a motorcycle. The angle of rake determines how stable the motorcycle feels.
[edit] Engine
Almost all commercially available motorcycles are driven by conventional gasoline internal combustion engines, but some small scooter-type models use an electric motor, and a very small number of diesel models exist (e.g., the USMC M1030 M1 version of the Kawasaki KLR650).
The Displacement is defined as the total volume of air/fuel mixture an engine can draw in during one complete engine cycle. In a piston engine, this is the volume that is swept as the pistons are moved from top dead center to bottom dead center. To the layperson this is the "size" of the engine. Motorcycle engines range from 50 cc (cubic centimetres), commonly found in many small scooters, to 2294 cc, the largest production engine, currently made by Triumph for its Rocket III cruiser-style motorcycle.
Motorcycles have mostly, but not exclusively, been produced with one to four cylinders, and designers have tried virtually every imaginable layout. The most common engine configurations today are the vertical single and twin, the V-twin, the opposed twin (or boxer), and the in-line triple and in-line four. A number of others designs have reached mass production, including the V-4, the flat 6-cylinder, the flat 4-cylinder, the in-line 6-cylinder, and the Wankel engine. Exotic engines, such as a radial piston engine, sometimes appear in custom built motorcycles.
Engines with more cylinders provide more power for the same displacement, and feel smoother to ride. Engines with fewer cylinders are cheaper, lighter, and easier to maintain. Liquid-cooled motorcycles have a radiator (exactly like the radiator on a car) which is the primary way their heat is dispersed. Coolant or oil is constantly circulated between this radiator and the cylinder when the engine is running. Air-cooled motorcycles rely on air blowing past fins on the engine case to disperse heat. Liquid cooled motorcycles have the potential for greater power at a given displacement, tighter tolerances, and longer operating life, whereas air cooled motorcycles are potentially cheaper to purchase, less mechanically complex and lighter weight.
An air cooled engine contracts and expands with its wider temperature range, requiring looser tolerances, and giving shorter engine life. The temperature range of an air cooled two stroke is even more extreme, and component life even shorter than in an air cooled four stroke.
As applied to motorcycles, two-stroke engines have some advantages over equivalent four-strokes: they are lighter, mechanically much simpler, and produce more power when operating at their best. But four-stroke engines are cleaner, more reliable, and deliver power over a much broader range of engine speeds. In developed countries, two-stroke road-bikes are rare, because - in addition to the reasons above - modifying them to meet contemporary emissions standards is prohibitively expensive. Almost all modern two-strokes are single-cylinder, air-cooled, and under 600 cc.
[edit] Transmission
Modern motorcycles normally have five or six forward gears. Only the largest touring motorcycles (most prominently, the Honda Goldwing) and a few models that are routinely used with a sidecar or converted to tricycle configuration are fitted with a reverse gear. These motorcycles' weight (in the region of 300 kg) means they cannot effectively be pushed without the motor engaged.
The clutch is typically an arrangement of plates stacked in alternating fashion, one geared on the inside to the engine and the next geared on the outside to the transmission input shaft. Whether wet (rotating in engine oil) or dry, the plates are squeezed together by a spring, causing friction buildup between the plates until they rotate as a single unit, driving the transmission directly. A lever on the handlebar exploits mechanical advantage through a cable or hydraulic arrangement to release the clutch spring, allowing the engine to freewheel with respect to the transmission.
The most commonly used transmission is a sequential gearbox. From neutral, either first or second gear can be selected, but higher gears may only be accessed in order - it is not possible to shift from second gear to fourth gear without shifting through third gear. A five-speed of this configuration is commonly said to be "one down, four up," and a six-speed is said to be "one down, five up" due to the placement of the gears with relation to neutral.
Final drive from the gearbox to the rear wheel is typically accomplished with a chain, which requires both lubrication and adjustment for elongation (stretch) that occurs through wear. The lubricant is subject to being thrown off the fast-moving chain and results in grime and dirt buildup. Chains do deteriorate, and excessive wear on the front and rear sprockets can be dangerous. Many manufacturers offer cruiser models with final drive options of a belt or a shaft. A belt drive is still subject to stretch, but operates very quietly, cleanly, and efficiently. However, belt drives are limited in the amount of power they can transmit. The belt is frequently toothed. A shaft drive is completely enclosed; the visual cue is a tube extending from the rear of the transmission to a bell housing on the rear wheel. Inside the bell housing a bevelled gear on the shaft mates with another on the wheel mount. This arrangement is superior in terms of noise and cleanliness, and is virtually maintenance free. However, the additional gearsets are a source of power loss and add weight.
Scooters normally have a continuously variable transmission (CVT). CVT is a type of automatic transmission (also occasionally used in cars) that can change the "gear ratio" (gears are not generally involved) to any one of infinite arbitrary settings within the limits. The CVT is not constrained to a small number of gear ratios, such as the 4 to 6 forward ratios in typical automotive transmissions. CVTs are ideally suited to 2-wheeled vehicles because of the lack of shift shock. A conventional automatic transmission might shift shock at an unexpected moment and upset the vehicle.
[edit] Wheels
The wheel rims are usually steel or aluminum (generally with steel spokes and an aluminium hub) or 'mag' type cast or machined aluminum. At one time, motorcycles all used spoke wheels built up from separate components (see wheelbuilding), but, except for dirtbikes, one-piece wheels are more common now. Performance racing motorcycles often use carbon-fiber wheels, but the expense of these wheels is prohibitively high for general usage.
[edit] Tires
Motorcycles mainly use pneumatic tires. However, in some cases such as off-road motorcycles, the tires are filled with a type of mousse which helps prevent punctures. Both types of tires come in many configurations. The most important characteristic of any tire is the contact patch. That is the small area that is in contact with the road surface while riding. There are tires designed for dirtbikes, touring, sport and cruiser bikes.
Dirtbike tires have knobby, deep treads for maximum grip on loose dirt, mud, or gravel; such tires tend to be less stable on paved surfaces. Touring tires are usually made of harder rubber for greater durability. They may last longer, but they tend to provide less outright grip than sports tyres at optimal operating temperatures. The payoff is that touring tires typically offer more grip at lower temperatures, meaning they can be more suitable for riding in cold or winter conditions where a sport tire may never reach the optimal operating temperature. Sport/performance tires provide amazing grip but may last 1,000 miles (1,600 km) or less. Cruiser and "sport touring" tires try to find the best compromise between grip and durability. There is also a type of tire developed specifically for racing. These tires offer the highest of levels of grip for cornering. Due to the high temperatures at which these tires typically operate, use on the street is unsafe because the tires will typically not reach optimum temperature before a rider arrives, thus providing almost no grip en route. In racing situations, racing tires would normally be brought up to temperature in advance by the use of tire warmers.
[edit] Brakes
There are generally two independent brakes on a motorcycle, one set on the front wheel and one on the rear. However, some models have "linked brakes" whereby both can be applied at the same time using only one control. Front brakes are generally much more powerful than rear brakes: roughly two thirds of stopping power comes from the front brake - mainly a result of weight transfer being much more pronounced compared to larger vehicles, due to the very short wheelbase . Brakes can either be drum or disc based, with disc brakes being more common on large, modern or expensive motorcycles for their far superior stopping power, particularly in wet conditions. There are many brake-performance-enhancing aftermarket parts available for most motorcycles including brake pads of varying compounds and steel braided brake lines.
In the 1980s, BMW introduced the antilock braking system (ABS) to the world of motorcycling. This life-saving advance has since been adopted for civilian motorcycles by some other manufacturers, including Honda, Suzuki, Yamaha, Kawasaki and Ducati. Some larger scooters also offer ABS brakes.
[edit] Suspension
Modern designs have the two wheels of a motorcycle connected to the chassis by a suspension arrangement, however 'chopper' style motorcycles often elect to forgo rear suspension, using a rigid frame.
The front suspension is usually built into the front fork and may consist of telescoping tubes called fork tubes which contain the suspension inside or some multibar linkage that incorporate the suspension externally.
The rear suspension supports the swingarm, which is attached via the swingarm pivot bolt to the frame and holds the axle of the rear wheel. The rear suspension can consist of several shock arrangements:
- Dual shocks, which are placed at the far ends of the swingarm
- Traditional monoshock, which is placed at the front of the swingarm, above the swingarm pivot bolt
- Softail style monoshock, which is mounted horizontally in front of the swingarm, below the swingarm pivot bolt
[edit] Instruments
With dirtbikes excluded, almost all motorcycles have a speedometer, an odometer and a tachometer. Fuel gauges are becoming more common, but traditionally a reserve tank arrangement is used with a petcock (petrol tap) on the side of the motorcycle allowing the rider to switch to a reserve fuel supply when the main fuel supply is exhausted. There is not actually a separate reserve tank: The intake for the petcock has two pipes, one extending higher into the fuel tank than the other. When fuel no longer covers the long pipe, the rider switches the petcock to the "reserve" setting, which accesses the shorter pipe. Riders whose bikes lack a fuel gauge (most machines prior to the past few years) usually learn how many miles/km they can go with a full tank of fuel, and then use a trip meter if available to judge when they must refill the tank.
[edit] Fairing
A plastic or fiberglass shell, known as a fairing, is placed over the frame on some models to shield the rider from the wind. Drag is the major factor that limits motorcycle speed, as it increases at the square of the velocity, with the resultant required power increasing with the cube of velocity. As can be seen from the streamlined appearance of new performance motorcycles, there is much aerodynamic technology included in the design. Unfortunately, since the 1958 FIM ban on "dustbin" fairings no major manufacturer has been bold enough to overcome the effect of the turbulence caused by the spinning front wheel, which prevents the motorcycle from cutting a clean path through the air. The "dustbin" fairing can improve aerodynamic performance without unacceptably compromising the rider's ability to control the machine, although with a weight penalty. In the absence of a fairing or windshield, a phenomenon known as the windsock effect occurs at speeds above 100 km/h, where the rider becomes a major source of drag and is pushed back from the handlebars, tiring the rider. However, these motorcycles still effectively push their way through the atmosphere with brute force.
Cabin cycle solved the problem of aerodynamics by isolating driver from outside air.
Modern fairings on touring and sport-touring motorcycles dramatically improve a rider's comfort and attention on long rides by reducing the effect of the wind and rain on the body. They also help keep a rider warm in cold weather, reducing hypothermia. Heated hand grips, and even heated seats, also improve rider comfort in cold weather. Some fairings now have electric windshields, which raise and lower the windshield with the push of a button to the optimum height for conditions. Originated by BMW, such windshields are now available as well on selected models from Honda, Yamaha, Kawasaki, and Moto Guzzi.
[edit] Fuel efficiency
Motorcycle fuel efficiency benefits from the relatively small mass of the vehicle, compared to its passengers and to other motor vehicles, and subsequent small engine displacement. However, poor aerodynamics of exposed passengers and engines designed for goals other than fuel economy can work to reduce these benefits.
Fuel effiency varies greatly with engine displacement from a low of 29 mpg U.S. (8.1 L/100km) reported by a Honda VTR1000F rider[1] to 107 mpg U.S. (2.2 L/100km) reported for the Verucci Nitro 50cc Scooter[2]. A specially designed Matzu Matsuzawa Honda XL125 achieved 470 mpg U.S. (0.5 L/100km) "on real highways - in real conditions."[3]
[edit] Dynamics
A motorcycle stays upright when it is steered to keep its center of gravity over its wheels. Lock the steering of a motorcycle and it is virtually impossible to ride. Cancel the gyroscopic effect of its rotating wheels by adding counter-rotating wheels, and it can still be easily ridden.
Except at extremely slow speeds, motorcycle must lean in order to turn. This lean is induced by a method known as countersteering. This however is a separate action to the rider leaning their body, as it is virtually impossible to steer a motorcycle through body leaning alone.
Short wheelbase motorcycles, such as sport bikes, can generate enough torque at the rear wheel and enough stopping force at the front wheel in order to flip longitudinally. These actions, especially if performed on purpose are known as wheelies and stoppies respectively.
[edit] Social aspects
[edit] Subcultures
Around the world, motorcycles have historically been associated with subcultures. Some of these subcultures have been loose-knit social groups such as the cafe racers of 1950s Britain, and the Mods and Rockers of the 1960s. A few are believed to be criminal gangs.
Social motorcyclist organizations are popular, the most well known of these being the American Motorcyclist Association, Harley Owners Group, Gold Wing Road Riders (GWRRA), and BMW MOA. These motorcycle organizations have enthusiastic members, and many raise money for charities through organized events and rides. GWRRA and BMW MOA hold large international rallies in different parts of the United States or Canada every year that are attended by many thousands of riders.
[edit] Mobility
In many cultures, motorcycles are the primary means of motorized transport, not automobiles. According to the Taiwanese government "the number of automobiles per ten thousands population is around 2,500, and the number of motorcycles is about 5,000."[4]
[edit] Safety
Motorcycles have a far higher rate of crippling and fatal accidents per unit distance than automobiles. According to the US Highway Safety Authority, in 2004 15.0 cars out of 100,000 ended up in fatal crashes. The rate for motorcycles is 69.3 per 100,000. The picture is much more grim when miles travelled are taken into account: in 2004, there was one motorcycle fatality per 2.5 million miles, compared to one passenger car fatality per 84.7 million miles ( ratio of 34 to 1 ). The most common type of motorcycle accident is caused by inattentive drivers making a turn directly in front of a motorcycle. Other leading causes of motorcycle accidents involve unlicensed and untrained riders and drunk or drugged riding.
Why do people ride motorcycles when faced with these facts? The most common answer offered by students in courses designed by the Motorcycle Safety Foundation throughout the United States is "the feeling of freedom." They like the openness of motorcycling, compared to the enclosure of an automobile. They like feeling the wind and smelling the environment through which they ride. Riding a motorcycle, they say, "is like flying an airplane on the ground," and leaning into turns becomes the essence of motorcycling.
Motorcycles are also a very economical mode of transport, with advantages in ease of parking and ability to avoid heavy traffic.
But there is more. The visual appeal of a motorcycle, with its engine and elements visible, appeals strongly to motorcyclists. The design of motorcycles is a powerful attractant, witness the famous Art of the Motorcycle [2] exhibit at the Guggenheim Museum in New York City, which has traveled internationally.
The two major causes of motorcycle accidents in the United States are (1) motorists pulling out or turning in front of motorcyclists and violating their rights-of-way, and (2) motorcyclists running wide in turns and crashing. Both of these crashes are made more likely when motorcyclists mix any amount of alcohol with riding. Motorcyclists can do much to anticipate and avoid these crashes by getting proper training, by increasing their conspicuity to other traffic, and by separating alcohol and riding.
The United Kingdom has a number of organisations which are dedicated to improving motorcycle safety by providing advanced rider training over and above what is necessary to pass the basic motorcycle test. These include the Institute of Advanced Motorists (IAM) and the Royal Society for the Prevention of Accidents (RoSPA). As well as gaining through increased personal safety, riders with these advanced qualifications often benefit from reduced insurance costs.
Motorcycle Safety Education is offered throughout the United States by a number of different organizations ranging from state agencies to non-profit organizations to corporations. The courses, designed by the Motorcycle Safety Foundation, include the Basic Rider Course, the Intermediate Rider Course and the Advanced Rider Course.
[edit] Types of motorcycles
There are many different types of motorcycles for many different purposes.
- Moped: Small, light, inexpensive, efficient rides for getting around town. Usually started by pedaling (motorcycle + pedals = moped).
- Dual-sport : A road-legal machine offering a compromise in highway and off-road performance, durability and comfort. Since the requirements are often conflicting, the manufacturer has to choose one or the other, resulting in a great variety of bikes in this category.
- Enduro: A road-legal version of a motocross machine, ie featuring high ground clearness and copious suspension with minimal creature comforts. Highly unsuitable for long distance road travel. The few features that are different form the motocross versions are the silencers, the flywheel weights and the presence of features necessary for highway use.
- Scooters: A motorbike with a step-through frame and generally smaller wheels than those of a traditional motorcycle. Can be riden without straddling any part of the bike. Available in sport, commuter, and touring models.
- Sport bikes: Fast, light, sleek motorcycles designed for maximum performance, for racing homologation or spirited road riding. They are distinguishable by their brightly colored plastic bodywork and the rider's tipped-forward seating position. They are also called "race replicas" because of their connection to the racing category for production motorcycles known as Superbike racing.
- Cruisers: A range of small to large motorcycles designed for comfort and looks with a relaxed upright seating position. They are notable for their heavy use of chrome and are often highly customized.
- Choppers: Highly customized motorcycles based on a cruiser-style frame with long rake (longer front forks) and wild paint jobs. These are created more for show than dependability and ridability.
- Street Custom: Highly customized motorcycles with wild paint jobs also built for show, but constructed from a sport bike bike frame instead of a cruiser-style frame.
- Touring motorcycles: Tour bikes are designed for rider and passenger comfort, luggage carrying capacity, and reliability. Cruisers, sport bikes and some dual-sports can also be used as touring bikes with the addition of aftermarket luggage and seats.
- Trials motorcycles: Made as light as possible, with no seat in order to provide maximum freedom of body positioning for use in observed trials competition; see Motorcycle Trials for more information about the sport.
- Sport touring: Sport-tourers are factory-built hybrids of a sport bike and a touring motorcyle, for those who desire the qualities of both.
- Standards: Standards have a riding position midway between the forward position of a sports bike and the reclined position of a cruiser. Unlike touring bikes, Standards often have little or no fairing. Luggage capabilities are often an optional extra. Standards are popular for commuting and other city riding as the upright riding position gives greater visibility in heavy traffic (both for the rider and to other road users).
- Dirt bikes/motocross bikes/off-road bikes: designed for racing, recreation, or sometimes long-distance touring in gravel/mud/sand conditions.
- Pocket bikes: Small imitations of sport bikes designed for recreation or racing by all age levels; see Pocketbike Racing.
- Mini bikes: Very small bikes designed to be simple and fun for children. Generally they have no clutch or shifting to simplify operation. Also known as Mini Motos.
[edit] Definition
A motorcycle is defined in some countries by law for the purposes of taxation or licensing riders as fit to drive. In the UK a moped "has a maximum design speed not exceeding 50 km/h...engine capacity no greater than 50 cc and can be moved by pedals, if first used before 1 August 1977". A "learner motorcycle", ie one that can be used before a full driving licence is obtained has an engine "up to 125 cc" with a power output not exceeding 11 kW.[3]
[edit] See also
- Category:Motorcycling
- Category:Motorcycles
- Category:Motorcycle technology
- Category:Motorcycle clubs
- Category:Motorcyclists organizations
- Category:Motorcycling events
- Category:Motorcycle racing
- Electric motorcycles and scooters
- List of motorcycle manufacturers
[edit] References
- ^ Total Motorcycle Fuel Economy Guide. Retrieved on 2006-08-14.
- ^ VERUCCI GAS SCOOTERS. Retrieved on 2006-08-15.
- ^ The Craig Vetter Fuel Economy Contests - 1980 thru 1985. Retrieved on 2006-08-15.
- ^ Sustainable Development Indicators for Taiwan. Retrieved on 2006-08-14.
[edit] External links
 |
Wikimedia Commons has media related to: |
- Motorcycle Safety Foundation
- American Motorcyclist Association is the largest motorcycling organization in the U.S. They sponsor racing leagues nationwide, and lobby for the rights of motorcyclists through the AMA-PAC political action committee.
- Fédération Internationale de Motocyclisme is the international governing body of motorcycle racing. The FIM also lobbies for the rights and interests of motorcyclists.
- Motorcycle.com - Internet's Oldest Motorcycle Magazine
