A motorcycle is a two-wheeled motorized vehicle, powered by an engine. The wheels are in-line, and the motorcyle remains upright when in motion by virtue of gyroscopic forces. The rider of a motorcycle sits astride the vehicle on a seat, with hands on a set of handlebars which are used to steer the motorcycle, and feet on a set of "footpegs" or "pegs" which stick out from the chassis.
Variations of this definition do exist: some motorcycles are equipped with footboards instead of footpegs, and sidecars and other three-wheeled variations may also be found.
(picture of bike in here)
The motorcycle's steering is controlled by the handlebars and the rider's positioning. At speed, the gyroscopic forces cause a phenomenon known as "counter-steer" to occur, where (for instance) pushing on the right handlebar and pulling on the left will cause the bike to lean to the left, and then execute a left hand turn. Turning can similarly be executed by changing body position, which causes the bike to lean and then turn. At speeds less than approximately 10km/h turning works in a fashion similar to a car or other two-track vehicle, with the motorcycle following the direction of the front wheel.
Turning a motorcycle is characterized by leaning the vehicle over. (physics of turning in here)
The chassis of a motorcycle is typically made from welded aluminium or steel struts, with the rear suspension being an integral component in the design. Some motorcycles include the engine as a load bearing member, however this is not common. A fairing is often placed over the frame, to shield the rider from the wind and decrease drag. Drag is the major factor limiting motorcycle speed as it increases at the square of the velocity. In the abscence 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.
The motor is controlled by a clutch lever under the left hand in standard configurations, a throttle on the right handlebar (where pushing the wrist down increases fuel to the engine and so causes the bike to accelerate) and a gear lever on the left foot. The gear lever typically operates by downshifting when the lever is depressed, and upshifting when the lever is lifted; neutral sits above first gear and below second, so a small lift out of first causes the gearbox to change into neutral, but a large movement causes the gearbox to change into second gear. Modern motorcycles normally have five or six forward gears. Only the largest touring motorcycles and a few archaic models that are routinely used with a sidecar are fitted with a reverse gear.
There are generally two independent brakes on a motorcycle, one on the front wheel, controlled by the right hand lever, and one on the rear controlled by the right foot. The front brake is generally much more powerful than the rear as the majority of stopping power comes from the front brake; rear wheels will generally lock and skid much more easily than the front. 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. Some manufacturers are creating motorcycles with ABS; others are creating linked brakes which actuate both rear and front brakes (althogh perhaps with different strengths) when either lever is depressed.
The motor of a motorcycle typically sits immediately under the rider's seat, between the legs. Almost all commercially available motorcycles are piston driven internal combustion engines, with typical sizes between 50cc and 1500cc. Larger motorcycles (above 500cc) on the modern market are mostly four stroke engines, but there is a sizable minority of two stroke engines on smaller motorcycles. Fuel injection is widely available on commercially available motorcycles. Two and four cylinder engines are the most common available; single cylinder engines are common on off-road bikes and small scooters. Thethere are commercially availabe three cylinder designs, and even a few five and six cylinder and V8 motorcycles commercially available. Two cylinder engines are most commonly found in either a "V-twin" configuration or a "parallel-twin" configuration. Most four-cylinder engines are in-line rather than v-shaped and arranged transversely, that is, the crankshaft is at a 90 degree angle to the frame. Both water-cooled and air-cooled engines are common.
Almost all motorcycles have a speedometer and odometer and many have a tachometer. Fuel gauges are becoming more common, however traditionally a reserve tank arrangement has been used with a tap on the left hand 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.
Transmisson/gearbox (don't know much about these - mention clutch. gearbox and final transmission belt/shaft/chain).
The two wheels of a motorcycle are connected to the chassis by a suspension arrangement. The front suspension generally consists of oil shock absorbers, however a variety of arrangements are used on the rear. The wheels use pneumatic tires, generally characterised by a rounded surface, to ensure good traction while leaning as described above. Correct tire pressure and correct adjustment of suspension are essential to safe cornering, far more so than in a four wheeled vehicle, as any loss of grip will probably lead to loss of control of the motorcycle.
Motorcycles are produced in a number of different configurations for different purposes.
Road motorcycles are motorcycles designed for being ridden on the road. They feature smooth tires, and engines generally in the 250cc and over range. Most are capable of speeds in excess of 100 km/h, and many of speeds in excess of 160km/h.
(picture of road bike)
Road motorcycles are themselves broken down into several sub-categories.
Cruisers. These motorcycles mimic the style of American machines from the 1930's to the early 1960's, such as those made by Harley-Davidson, Indian, Excelsior and Henderson, even though they have benefited from advances in metallurgy and design. The riding position places the feet forward and the hands up, with the spine erect or leaning back slightly. Cruisers are less suitable for high-speed riding, and are often used to signal adherence to an alternative lifestyle, the most extreme form of which is found in motorcycle gangs such as the Hell's Angels. Choppers are extreme cruiser configurations where the handlebars rise to a level above the riders shoulders with very long forks. They are notable for their extreme looks and equally extreme handling characteristics.
Sports Bikes. These motorcycles are visually similar to machines used in motorcycle racing and are generally only a few years behind the real racing machines. The riding position places the feet towards the back, the hands low and the spine inclined forward.
Touring and Sport Touring. Touring motorcycles are characterised by wind protection for the rider (in the form of a fairing or windscreen) and the ability to carry some amount of luggage (usually in the form of panniers and/or a topbox mounted towards the rear of the motorcycle). Although any motorcycle can be so equipped and used to tour with, specialised touring motorcycles such as the Honda Goldwing have become increasingly popular. Sport tourers are a hybrid form between sporting bikes and tourers and allow long-distance riding at higher speeds - the first example of this type of motorcycle was the BMW R100RS. Another hybrid is the custom tourer, which combines cruiser and tourer characteristics - the original form of this type is the Harley-Davidson Electra-Glide.
Standard. Also known as the "naked" bike, this is the basic form of the motorcycle. No longer as popular as in earlier days, when this was the only form of motorcycle commercially available. This style of motorcycle is however seeing a resurgence as at the end of 2000, with many manufacurers releasing new models with minimal fairings.
Scooters are vehicles similar to motorcycles also designed for being ridden on the road. They are characterized by small wheels, small (generally less than 125cc) engines, and a step-through configuration allowing the rider to ride with both feet on a running-board and knees together.
(picture of scooter)
Off-road motorcycles are motorcycles designed for being ridden in rougher terrain. They are also known as "dirt bikes" and "trail bikes". An off-road motorcycle will typically have suspension with more travel than a road bike, higher ground clearance and hence a higher centre of gravity, and a small (less than 500cc) single cylinder motor.
(picture of trailie)
Motorcross & trials.(more here)
Odd motorcycles - turbine driven etc. (more here)
History / people (many pages started already)
- Aprilia (includes the Moto-Guzzi and Laverda brands)
- Moto Guzzi
Motorcycle manufacturers no longer in production:
1. The Triumph brand has existed in two distinct eras, one at Meriden and one at Hinckley, with a ten-year hiatus between the two.
motorcycle racing (I suggest a different page for this one - clasqm)