Grand Prix motorcycle racing
Grand Prix motorcycle racing refers to the premier categories of motorcycle road racing. The category is commonly referred to simply as GP racing or MotoGP. Premier class GP motorcycles are prototype racing machines that are not available for general purchase (road-going versions of the 125 and 250cc machines are available). This contrasts with the various production categories of racing, such as World Superbike, that feature modified versions of motorcycles available to the public. Currently there are three engine displacement categories of Grand Prix motorcycles: 125 cc, 250 cc and MotoGP (up to 990 cc). In 2007, the MotoGP class will have its maximum engine displacement capacity reduced to 800 cc, ostensibly for safety reasons.
A World Championship for motorcycle racing was first organized by the Fédération Internationale de Motocyclisme (FIM) in 1949. There have traditionally been several races at each event for various classes of motorcycles, based on engine size, and one class for sidecars. Classes for 50cc, 125cc, 250cc, 350cc, and 500cc single seaters have existed over time, and 350cc and 500cc sidecars. Up through the 1950s and most of the 1960s, four-stroke engines dominated all classes. In the 1960s, two-stroke engines began to take root in the smaller classes. By the 1970s, two-strokes completely eclipsed the four-strokes. In 1979, Honda made an attempt to return the four-stroke to the top class, with the NR500, but this project failed, and in 1983, even Honda was winning with a two-stroke 500. The 50cc class was replaced by an 80cc class, then the class was dropped entirely in the 1990s, after being dominated primarily by Spanish and Italian makes. The 350cc class vanished in the 1980s. Sidecars were dropped from World Championship events in the 1990s, reducing the field to 125s, 250s, and 500s.
The premier class of GP motorcycle racing has changed dramatically in recent years. From the mid-1970s until 2002 the top class of GP racing was restricted to four cylinders and 500 cc, regardless of whether the engine was a two-stroke or four-stroke. Consequently, all machines were two-strokes, due to the greater power output for a given engine capacity. In 2002 manufacturers were first permitted to enlarge the total capacity of four stroke machines to a maximum of 990 cc, and to employ their choice of three to six cylinders.
A 500 cc two-stroke machine should, in theory, deliver similar power to a 990 cc four-stroke machine, and the 2002 field was comprised of numerous machines of each engine type. However, it rapidly became apparent that the four-stroke machines were outperforming the two-strokes in almost every area. As a result, in 2003 there were no two-stroke machines remaining in the field. The 125 cc and 250 cc classes still consist exclusively of two-stroke machines.
Since nearly all medium and large capacity (over 250 cc) road motorcycles have four-stroke engines, most manufacturers benefit more directly from the technology developed in road racing if they use four-stroke racing engines. Recent decisions by the EU to prohibit the sale of two-stroke machines to the general public have raised doubts about the long-term viability of two-stroke motorcycle racing classes, although there has been no official announcements from any of the ruling organisations.
Beginning in 2007, the displacement of MotoGP class machines will be restricted to 800 cc. The stated reason for this reduction is to improve rider safety, as the power output and top speed of MotoGP machines has been increasing substantially since 2002. The current MotoGP speed record of 325.9kmh (202.5 mph) was set by Loris Capirossi on a Ducati at Mugello in 2003. By way of comparison, the current Formula One speed record of 369.9 km/h (229.8 mph) was set by Antonio Pizzonia of the BMW WilliamsF1 team, at Monza in 2004.
The specific choice of a reduction to 800 cc (as opposed to other power reduction methods, such as decreasing the number of transmission gears permitted) is very favourable to Honda, who currently run a five cylinder machine, and need only remove a cylinder to modify their engine. Other manufacturers will need to entirely redesign their engines. Cynical journalists have suggested that this power reduction decision came about due to pressure from Honda, but there is no public evidence to support this claim.
MotoGP bikes are permitted to have engines with 3 to 6 cylinders, and have variable weight limits depending on the number of cylinders. This is because an engine with more cylinders for a given capacity means the engine can produce more power, and the weight limit is increased as a form of handicap. In 2004 motorcycles were entered with three-, four- and five-cylinder configurations. 2005 is awaiting the additional entry of a six-cylinder machine from Blata.
Like Formula One cars, GP motorcycles are made not only to be raced but to demonstrate the technical and design prowess of the manufacturer. As a result, MotoGP machines are generally made of lightweight and expensive materials such as titanium and carbon-fiber-reinforced plastic. They regularly feature technology not available to the general public.
Examples of this include sophisticated electronics, including telemetry, engine management systems and traction control, carbon disk brakes, and advanced engine technology such as Honda's V5 engine configuration and Aprilia's RS3. The latter employs the Cosworth-designed pneumatic valve actuation system, used in Formula One cars.
While MotoGP motorcycles are only raced at World Championship level, slightly less powerful 125 cc and 250 cc bikes are available at relatively reasonable cost. A 125 cc bike costs about the same as a small car. These bikes are raced in national championships around the world.
One of the main challenges that confronts a MotoGP motorcycle rider and designer is how to translate the machine's enormous power - around 240 horsepower (179 kW), through a single tyre-contact patch roughly the size of a human hand. For comparison, Formula 1 cars produce up to 950 bhp ((700 kW) from their three-litre engines but have 10 times the tyre contact surface. Because of this difficulty, MotoGP is perhaps unique in modern motor sport in that teams will often deliberately detune their engines to allow their riders a chance to control them, with most not making more than the 180 to 190 bhp (135 to 140 kW) of the front-running two-stroke bikes.
The top riders travel the world to compete in the annual World Championship series. The circuit is perhaps most closely followed in Spain and Italy, home of many of the more successful riders at the moment. However, over the last couple of years there has been an increase in the number of riders competing from the USA. This has resulted in the reintroduction in 2005 of the US Grand Prix, an event staged at Laguna Seca where American Nicky Hayden took his maiden MotoGP victory.