Motorcycle
A motorcycle (or motorbike in United Kingdom, Ireland, Australia and New Zealand) is a single-track, two-wheeled motor-vehicle powered by an engine. Styles of motorcycles vary depending on the task for which they are designed, such as long distance travel, navigating congested urban traffic, cruising, sport and racing, or off-road conditions. Motorcycles are among the least expensive and most widespread forms of motorised transport in many parts of the world.
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.
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.
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 honor 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 aluminium housing.
Police officers have used motorcycles — primarily for the enforcement of traffic laws — from the early 20th century. Called motor officers in the United States, these officers call their vehicles simply "motors."'
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.
Technical Aspects
Construction
the 250 cc Ariel Leader
The construction of modern motorcycles has mostly standardized on the following key components.
Chassis
The chassis (or frame) of a motorcycle is typically made from welded aluminium or steel (or 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 is held in the frame.
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.
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 centre to bottom dead centre. To the layperson this is the "size" of the engine. Motorcycle engines range from less than 50 cc (cubic centimetres), commonly found in many small scooters, to 5735cc, a Chevrolet V8 engine, currently used by Boss Hoss in it's 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, liquid-cooled, and under 600 cc.
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. On some, it is not really a reverse gear, but a feature of the starter motor which when reversed, performs the same function. 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 build up 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.
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.
Final drive
Power transfer 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 build up. 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. A gilmer belt is frequently used. A shaft drive is usually 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.
Wheels
The wheel rims are usually steel or aluminium (generally with steel spokes and an aluminium hub) or 'mag' type cast or machined aluminium. 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-fibre wheels, but the expense of these wheels is prohibitively high for general usage.
Tires
Motorcycles mainly use pneumatic tires. However, in some cases where punctures are common (some enduros), the tyres are filled with a "mousse" which is unpunctureable. Both types of tire 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 knobbly, 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 tires 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 whereas 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 tyres 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.
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 1981, BMW introduced an antilock braking system (ABS) to the world of motorcycling. This life-saving advance was quickly adopted for use on motorcycles by Honda. Other manufacturers, including Suzuki, Yamaha, Kawasaki, Triumph, Ducati, KTM, and Harley-Davidson have since also adopted this technology, although Harley only offers it on some police motorcycles and not on civilian motorcycles. Smaller capacity motorcycles, below 650cc, tend not to have ABS. Some motor scooters, both small and large, also have ABS brakes.
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
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 longer 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/kilometres 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.
Additions
Various additions may be attached to a motorcycle or come as an integral part of a motorcycle from the factory.
Fairing
2007 BMW R1200RT.
A plastic or fibreglass 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.
Sidecar
A sidecar is a one-wheeled device attached to the side of a motorcycle, producing a three-wheeled vehicle. Early sidecars were intended to be removable devices that could be detached from the motorcycle.
Trunk
A motorcycle trunk is a storage compartment in the vicinity of the seat, other than panniers or saddlebags. A trunk mounted above and to the rear of the seat is also called a top box.
Fuel economy
Motorcycle fuel economy 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 economy 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]
Dynamics
Motorcycles must be leaned in order to turn. This lean can be induced by a method known as countersteering, in which the rider turns the handlebars in the direction opposite of the desired direction of turn. In other words, press forward on the handgrip in the desired direction — press right to go right, press left to go left. This concept, which is counter-intuitive and often very confusing to novices — and even to many experienced motorcyclists — is called countersteering.
The primary effect of countersteering is to shift the front tire contact patch such that a lean is initiated. Other methods allegedly used for turning a motorcycle, such as shifting weight to the side or the pegs, only help leaning the body of the motorcycle towards a direction; thus turning the front wheel in the opposite direction for preserving angular momentum, and eventually resulting in countersteering.
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.
Social aspects
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.
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]
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 while the rate for motorcycles is 69.3 per 100,000. The picture is grimmer when distance travelled are taken into account: in 2004 in the U.S., there was 0.4 fatalities per million miles compared to 0.012 passenger car fatalities per 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.
Even though statistics appear fearsome, people still desire to ride motorcycles. In courses designed by the Motorcycle Safety Foundation throughout the United States, the most common student justification 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.
The visual appeal of a motorcycle, with visible engine and elements, is also a persuading factor. The design of motorcycles has even inspired fine art, such as those in the Art of the Motorcycle 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.
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, i.e., featuring high ground clearance and copious suspension with minimal creature comforts. Highly unsuitable for long distance road travel. The features that differ from the motocross versions are the silencers, the flywheel weights and the presence of features necessary for highway use.
- Supermotard: Beginning in the mid-1990s, motocross machines fitted with street wheels and tires similar to those used on Sport bikes began to appear. These are known as "Supermotards", and riders of these machines compete in specially organized rallys and races.
- Scooters: A motorbike with a step-through frame and generally smaller wheels than those of a traditional motorcycle. Can be ridden 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 or spirited road riding. They are distinguishable by their brightly coloured 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 customised motorcycles with wild paint jobs also built for show, but constructed from a sport 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 motorcycle, 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.
- Electric Motorcycles: Nearly silent, zero-emission electric motor driven vehicles. Though electric motorcycles are emission free during operation, producing the electricity that charges the batteries in them does cause pollution. Range and top speed suffer because of limitations of battery technology.
- 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.
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.[2]
See also
References
- ^ "Total Motorcycle Fuel Economy Guide". Retrieved 2006-08-14.
- ^ "VERUCCI GAS SCOOTERS". Retrieved 2006-08-15.
- ^ "The Craig Vetter Fuel Economy Contests - 1980 thru 1985". Retrieved 2006-08-15.
- ^ "Sustainable Development Indicators for Taiwan". Retrieved 2006-08-14.
External links
- Motorcycle Safety Foundation
- American Motorcyclist Association is the largest motorcycling organization in the U.S. It is the governing body of motorcycle sport in the US, and lobbies 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.
- Getting started riding