Motocross is a form of motorcycle or ATV racing held on enclosed off-road circuits and is the widely considered the world's most popular form of motorcycle racing. Motocross is derived from the French, and was originally called Scrambling when the sport was invented in the UK. The name "motocross" is a contraction derived from the words "Motorcycle" and "Cross Country". Motocross is often abbreviated as MX.

Motocross tracks are often quite large and incorporate natural terrain features with very few man made jumps, unlike Supercross, a sport that was originally derived from Motocross and is executed on a smaller track with more extreme man made obstacles. It is not unheard of for a Motocross track to be made up entirely of hills and turns with no jumps at all. Due to the size of the track, motocross races often include more than 40 racers whereas Supercross races are generally limited to about 25.

Professional races measaured by time. A typical Pro race will run for 30 minutes, then once the leader crosses the finish line that lap, he is given a signal indicating there are two laps remaining. A one-lap-to-go signal is given at the start of the final lap, and the race is completed at the end of that lap. This format is known as 30 minutes plus 2 laps.

Other formats may be determined by laps. In each race there is a set number of laps and the first rider to complete the set number of laps is the victor. The first three riders that finish first are declared the podium riders because of the first though third positions in the race. Races are ran in sessions called motos. There are two motos in a race and the riders place in those heats are averaged together to get their overall finish.

Machines
Motocross motorcycles are lightweight and powered by highly tuned two-stroke or four-stroke engines (but usually geared for quick acceleration rather than very high speeds). They have knobby tires for traction on loose surfaces, a highly absorbent suspension designed to cope with the shock of heavy landings, and short gearing designed for swift acceleration rather than high top speed. They feature hinged footpegs and levers so that they simply fold rather than bend or snap when the machine is inevitably dropped. Also the exhaust may be routed carefully so that a fall will not damage the exhaust, nor bend it so that it would obstruct the rear swing arm's travel - something that does happen to road bikes. The saddle (seat) is curiously shaped, in a long banana, to extend from rear of the fuel tank to the rear fender. This offers the rider greater protection when he or she hits bumps or lands hard and allows the rider to move and distribute his or her weight over the front or rear of the bike. This will affect rotation pitch while jumping and greater traction to the front wheel when necessary on the ground. Lowering the rider's center of gravity (sitting) greatly increases the ability to go through a turn at higher speeds. Sitting further back and accelerating hard over a series of bumps or ("whoops") keeps the front tire from dropping into any large gaps between them and causing you to lose control of the bike. The gyroscopic effect of the engine along with the wheels makes jumping the "motocross" bike over long distances possible - this effect keeps the bike from rotating through any axis other than the axis of the wheels while in the air. A common technique to change the attitude of the bike in air involves the use of the rear brake. When the rear wheel is decelerated while the bike is in mid-air, angular momentum is transferred from the wheel to the entire bike. This forces the front of the bike lower (and likewise, accelerating the rear wheel causes the front of the bike to rise), allowing the rider to force the bike to a specific position or attitude relative to the ground.

Unusual for racing machines, motocross bikes can be purchased in a ready-to-race condition at moderate prices from major motorcycle manufacturers.

Professional riders, however, modify their machines further, both for outright performance and to have the bike's behaviour more in tune with their own preferences. The highly tuned machines of the professionals are called "factory bikes." The latest trend in motocross motorcycles is towards four-stroke engines. Although the four-strokes weigh more, they have much more power to back up the weight. These engines have been developed due to manufacturer's pressure and environmental concerns regarding the increased emissions of two-strokes. Some predict that two-strokes will not be available to buy after 2008, perhaps earlier in states such as California.

Engine sizes ranges from 50cc right up to 550cc, although bikes with sidecars can have up 1000cc engines. Four stroke motocrossers do not compete on a truly level playing field. Currently, 250cc four strokes compete in the 125cc class and 450cc four strokes are used in the 250cc class. They are very competitive in these classes but need twice the displacement to rival a two-stroke. However, the popularity of four-stroke motocross bikes has been steadily increasing. Due to the increase in popularity and to non-matching displacements of four-stroke and two-stroke motorcycles in the same classes, in the year 2005 the AMA changed the class names from 250cc to Pro, and from 125cc to Pro Lite. Thus, the former 125cc Supercross series is now referred to as AMA Supercross Pro Lites; the 250cc Motocross series is now AMA Motocross Pro; etc.

See also Motorcycle - especially the "Construction", "Dirt bike/Trail bike" and "Farm bike" sections


Manufacturers
Incomplete list

Current

Honda (Japan) 
Kawasaki (Japan) 
Suzuki (Japan) 
Yamaha (Japan) 
KTM (Austria) 
The above five are the major five manufactures in most markets, the manufactures below command little market share (currently - 2005).

Husaberg (Sweden) 
Aprilia (Italy) 
TM (Italy) 
VOR (Italy) 
Vertemati (Italy) 
Husqvarna (Italy, ex Sweden) 
Previous

Cannondale (USA) 
Maico (West Germany) 
CCM (UK) 

See also the List of motorcycle manufacturers


Event
The object of the contest is to complete either a defined number of laps (usually three to seven for amateurs, more for professionals) or fixed time period (anything up to 40 minutes) first. This competition is called a moto. Usually a race consists of two or three motos with the scores combined to determine the overall result.

Motocross racing is one of the most visually appealing forms of motorsport, with riders performing seemingly death-defying leaps, turns visibly at the edge of traction (as indicated by a sliding, spinning rear tire throwing dirt at all behind it), and the effort of riders clearly visible as they move their bodies around their motorcycles to balance the bikes for maximum speed.
Recently the sport has evolved with sub disciplines like Supercross and Arenacross (both are indoor motocross), Freestyle (or FMX) (a display of jumping skill rather than racing) and Supermoto (Motocross machines racing on both tarmac and off road).

Motocross can be an entry sport for motorsports in general. Classes for children as young as 4 years old exist for competition on 50cc machines.


Physical demands
One of the least understood aspects of motocross racing by non-participants is the extreme level of physical fitness required of competitors. Those unfamiliar with the sport often assume that the rider is doing nothing more strenuous than steering a motorized vehicle around a field, no more demanding than driving the family car around the block. In truth, motocross racing has been found to be one of the most physically demanding sports in existence. Observing in detail a rider's actions while at speed on the track reveals why. He or she must maintain ultra-precise control of a machine traversing terrain that most people would have difficulty walking across while maintaining as high of a rate of speed as possible. The rider is astride a machine weighing at least two hundred pounds and, at the most elite professional level, has an engine that produces at least fifty horsepower. A rider's arms and legs are in constant motion during a race, fighting for control of the motorcycle and absorbing the energy produced by high-speed landings from heights that often exceed twenty feet or from two-foot high stutter bumps (called whoops) that jackhammer the motorcycle and the rider. The G forces produced test the absolute limits of a rider's strength and endurance. Finally, a typical professional moto (heat race) lasts at least thirty minutes. That represents half of an hour in which the faster the rider goes, the more violently and frequently he or she is punished. And there are no pauses, breaks or pit stops. At least not if a rider expects to win. [citation needed]

The National Sport Health Institute in Englewood, California tested several professional motocross racers in the early 1980s as part of a comparative study of the cardio-vascular fitness of athletes from various disciplines. Athletes from track, American football and soccer were tested, among others. The cardiac stress and strength test results compiled there revealed that the motocross subjects had as high of a fitness level as than any other discipline tested. (original article appeared in DirtBike magazine in 1980. Interview with Brad Lackey, World Motocross Champion and one of the test's participants appeared in Racer X Illustrated in 2004 and is recounted here)


ATV Motocross
Starting in the year 2002, ATV motocross started to see a dramatic increase in participation across the United States. This was a direct result of the major ATV manufacturers getting involved in the sport. Before we can talk about the current state of ATV motocross, we must understand the past. ATV motocross floundered after Honda, Kawasaki, Suzuki and Yamaha dropped ATV-racing support in the mid 1980s due to the bad publicity of the vehicles. Throughout the late 1980s and all during the 1990s, aftermarket companies kept the sport alive, but barely. Racers would build expensive, custom ATVs with parts from major aftermarket manufacturers like Laeger's, Walsh Race Craft and Lonestar Racing. The engine that kept racing alive was the Honda TRX250R engine that was manufactured from 1986 to 1989. Again, the aftermarket helped racers get all they could out of the dated engine. Companies like Curtis Sparks Racing Engines, Baldwin Motorsports and Hinson Racing made it so the only stock component of the 250R engine were the left and right engine cases. Suspension upgrades made it possible for ATVs to hit jumps never thought possible. Suspension companies like PEP and Custom Axis, combined with long-travel A-arms and rear suspension links smoothed out rough tracks and harsh landings.

However, in order to be competitive on the motocross track, it was necessary to spend upwards of $20,000 on the race ATV. In the late 90s, rules were changed to allow racers to use dirt bike engines in ATV frames. The era of the four-stroke hybrid race ATV was born when Harold Goodman piloted a custom-built YZ400F to a national Four-Stroke Pro-Am championship. Soon hybrid machines were all over the tracks.

The manufacturers started paying closer attention to the sport ATV market, and in 1999 Honda released the four-stroke TRX400EX. While it wasn't as powerful as the hybrids racing on the tracks, it was a positive step. In 2001, Cannondale entered the ATV market and even fielded an ATV racing team in partnership with Nac's Racing the following year. The Cannondale story was a short one as the company declared bankruptcy shortly after 2002. In 2003 Suzuki released the LT-Z400 that featured a liquid-cooled four-stroke powerplant. That same year, the ATVA instituted a Pro Production class at the motocross nationals in order to showcase "stock" ATVs. The traditional Pro class still allowed two-strokes and hybrids. Many Pro racers raced both classes, but the premier class was still the Pro class. Tim Farr, in a move that raised eyebrows, raced only the Pro Production class. Doug Gust won the Pro Production class while Jeremiah Jones won the Pro class. Jones' championship would be the last Pro-class championship on a two-stroke.

Late in the 2003, Yamaha announced the YFZ450 for the 2004 model year. This ATV represented the first time a major manufacturer built a high-performance sport ATV suited for racing. While it wasn't as wide as many wanted for motocross and didn't have long-travel suspension, it featured a four-stroke engine very similar to the motocross dirt bikes Yamaha was putting out. The ATV also came stock with fully adjustable front suspension, the first time this was available on a stock ATV. After the Yamaha announcement, Honda announced it was going to bring the TRX450R to market in 2004. The tide was turning for the high-performance race ATV market.

The 2004 national motocross season was one of the most anticipated in 15 years. Suzuki announced it was going to hire Doug Gust as its motocross pilot, Honda was hiring Tim Farr as its factory racer and Yamaha was going to offer support Kory Ellis in limited fashion for the season. This represented the first time since around 1986 that any manufacturer was offering factory support for ATV racing. The moved proved to be a successful one for Suzuki as Doug Gust walked away with the national motocross championship, and in the process winning six overalls in a row.

The 2005 season saw more factory support and Suzuki fielding two racers, Gust and Jeremiah Jones, out of the Yoshimura/Suzuki semi. That year it was Honda winning the championship with support rider John Natalie taking the motocross championship. The 2005 season proved that the factories were willing to support ATV racing as they never had before. With that support on the track also meant support in the dealerships in the way of new, updated machines.

In the summer of 2005, Suzuki announced it was going to produce the 2006 LT-R450. This sport ATV was the most motocross-ready ATV ever produced. It featured electronic fuel injection, a high-performance four-stroke engine and a chassis that could be competitive in stock form. The front end had high-end shocks with 10 inches of travel and a width approaching 50 inches. The rear tires with 18-inch tires just like motocrossers sport. The swingarm was made of steel, too.

In 2005, local tracks mirrored the national tracks as more and more racers were bringing ATVs to race thanks to raceable models. Many feel that 2006 will be the biggest yet as the nationals continue to grow and many local AMA districts are offering "quad-only" race weekends.


Sidecars
Sidecar racing, known as Sidecarcross has been around since the 50’s but has declined in popularity since the 90’s. This variant is common in Europe, with a few followers in USA, New Zealand and Australia. Motocross sidecars are purpose built frames that resemble an ordinary motocross-cycle with a flat platform to stand on attached to either side and a handlebar at waist height to hold on to. The side of the "chair" (slang for the platform) usually follows the side of the road the nation in question drives upon, but not always. The passenger balances the bike by being a counterweight, especially in corners and on jumps. It’s driven on ordinary crosstracks. It is very physically demanding, especially for the passenger. This is reflected in most in the Swedish term for passenger- "burkslav", roughly translated as trunk/body/barrel-slave. This name comes from the early sidecars where the platform looked like a real road-sidecar and not today's platform.

The major frame builders today (2004) are VMC, BSU, AYR, EML and Woodenleg. Ordinary engines can be used, but size matters and two engines purpose built for sidecars exist, Zabel (Germany) and MTH (Austria) are most common. Fourstrokes are getting more common, usually KTM(Austria).


Freestyle
Freestyle motocross (FMX), a relatively new sport, is not racing and instead concentrates on performing acrobatic stunts while jumping motocross bikes. The winner is chosen by a group of judges. The riders are scored on style, level of trick difficulty, best use of the course, and frequently crowd reactions as well.

One stunt performed is the backflip, which was first performed successfully on a large bike by Caleb Wyatt. Some consider the body varial 360 as the most difficult stunt being performed at this time. This stunt, also called the Carolla, was first performed by Chuck Carothers at the 2004 X Games. Prior to this, the backflip 360, or off-axis backflip, was widely considered the most challenging stunt.


Minibikes
The latest craze is adult racing on miniature (50cc) motorcycles called a minibike. These inexpensive minibikes designed for small children are often transformed for adult use by adding taller handle bars and by improving the suspension.

In 1998 Australian minibike riders Jonathan Byrne and Nicholas Stephenson revolutionised the sport by launching them from a up ramp to a down ramp while copying the mid air monuvers done on a large bike in freestyle motocross. This type of minibiking is now called freestyle minibike riding. Since 1998 this type of sport has spread all over the world. [citation needed]


Supermoto
Supermoto is a recent invention involving racing Motocross bikes on a part concrete, part off road track, with "road" tires instead of off road tires. Some tracks for these race events have jumps, berms, and whoop-dee-doos just like true motocross tracks. For special events, the Supermoto track may incorporate metal ramps for jumps that can be disassembled and taken to other locations. Supermoto races may take place at modified go-kart tracks, road racing tracks, or even street racing tracks. There are also classes for kids such as the 85cc class.


Governing bodies
The sport is governed world wide by the FIM, with federations in many nations.

Incomplete listing

USA - AMA 
UK - ACU, with other separate (unconnected) bodies like the AMCA, ORPA, BSMA, and YSMA. 
Ireland - MCUI (covering the whole island) 
France - FFM 
Canada - CMRC / CMA 
South Africa - MSA 
Sweden - SVEMO