Difference between revisions of "Motorcycle"

[[image:mobike.cagiva.750pix.jpg|thumb|250px|A 125 cc motorcycle, the Italian-manufactured Cagiva Planet.]]

 

 

On a typical motorcycle  the operator sits [[wiktionary: astride|astride]] the vehicle on a seat, with their hands on a set of handlebars and their 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 side handlebar grip with [[#Brakes|braking]] being controlled with a hand-lever and foot pedal.

The inspiration for the earliest motorcycles, and arguably the first motorcycle, was designed and built by the German inventors [[Diamler|Gottlieb Daimler]] and Wilhelm Maybach in Cannstatt (since 1905 a city district of Stuttgart) in 1885. It was the first [[petroleum]]-powered vehicle ever, but for the provision of a pair of stabilizing wheels, a motorized bicycle, although they 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. 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 "bone-crusher" bike.  

In 1894, the [[Hildebrand & Wolfmüller]] was the first motorcycle that was available for purchase.   

Up 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. After the Second World War, in 1951, the [[BSA|BSA Group]] became the largest producer of motorcycles in the world. The German [[NSU]] was the largest manufacturer from 1955 until the 1970s when Honda became the most prominent manufacturer, a title it retains to this day. British manufacturers (Triumph, BSA, Norton) held 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 faster, cheaper and of better quality. Today, the Japanese manufacturers [[Honda]], [[Kawasaki]], [[Suzuki]] and [[Yamaha Motor Corporation|Yamaha]] dominate the motorcycle industry, although [[Harley-Davidson]] still maintains a high degree of popularity in America.

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 is used in a few very expensive custom frames.

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, no one has been able 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. Another problem is the fact that no designs have been discovered that can improve aerodynamic performance without unacceptably compromising the rider's ability to control the machine. 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.

The wheel rims are usually steel or aluminum (generally with steel spokes and an aluminium hub) or 'mag' type [[casting|cast]] or [[machining|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.

Almost all commercially available motorcycles are driven by conventional gasoline [[internal combustion engine]]s, but some small scooter-type models use an [[electric motor]], and a very small number of [[diesel engine|diesel]] models exist (e.g., the [[USMC]] M1030 M1).  

The [[Engine displacement|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 centimetre]]s), commonly found in many small scooters, to 2294 cc, the largest production engine currently made by Triumph for its '''Rocket III''' cruiser-style motorcycle.

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]] are fitted with a reverse gear.

The clutch is typically an arrangement of plates stacked in alternating fashion, one geared on the inside to the engine, and 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, through a cable or hydraulic arrangement, uses mechanical advantage to release the clutch spring, allowing the engine to freewheel with respect to the transmission.

Final drive from the gearbox to the rear wheel is typically accomplished with a chain, which requires both lubrication and adjustment for elongation (stretch) 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, cleanliness, and is virtually maintenance free. However, the additional gearsets are a source of power loss and add to bike weight.

Motorcycles mainly use [[pneumatic tire]]s ('tyres' in the UK) however, in some cases with 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 being the contact patch. That is the small area that is in contact with the road surface while riding.  

Some cruiser tires have raised white lettering on the sidewalls as a "[[retro]]" detail.

With dirtbikes excluded, almost all motorcycles have a [[speedometer]], an [[odometer]] and a [[tachometer]]. [[Fuel gauge]]s are becoming more common, however traditionally a reserve tank arrangement has been 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; this is typically done while the vehicle is in motion. 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 to the shorter pipe. Riders without a fuel gauge 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.