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Trail Braking
Trail braking is a driving and motorcycle riding technique where the brakes are used beyond the entrance to a turn (turn-in), and then gradually released (trailed off). Depending on a number of factors, the driver fully releases brake pressure at any point between turn-in and the apex of the turn. Motorcycling In applying this technique, motorcycle riders approach turns applying front brakes to reduce speed. As they enter the turn, they slowly ease off the brakes, gradually decreasing or trailing off the brakes as motorcycle lean increases. This is done for several reasons. First, it gives more traction because the downward force on the front tire is increased by load transfer. Second, as the brakes are applied and the weight shifts forward, the forks are compressed. The compression of the forks changes the motorcycle's steering geometry, decreasing stability in a way that makes the motorcycle more apt to lean and more quickly change direction. Third, decreasing speed decrea ...
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Trailbraking
Trail braking is a driving and motorcycle riding technique where the brakes are used beyond the entrance to a turn (turn-in), and then gradually released (trailed off). Depending on a number of factors, the driver fully releases brake pressure at any point between turn-in and the apex of the turn. Motorcycling In applying this technique, motorcycle riders approach turns applying front brakes to reduce speed. As they enter the turn, they slowly ease off the brakes, gradually decreasing or trailing off the brakes as motorcycle lean increases. This is done for several reasons. First, it gives more traction because the downward force on the front tire is increased by load transfer. Second, as the brakes are applied and the weight shifts forward, the forks are compressed. The compression of the forks changes the motorcycle's steering geometry, decreasing stability in a way that makes the motorcycle more apt to lean and more quickly change direction. Third, decreasing speed decrea ...
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American Motorcyclist Association
The American Motorcyclist Association (AMA) is an American nonprofit organization of more than 200,000 motorcyclists that organizes numerous motorcycling activities and campaigns for motorcyclists' legal rights. Its mission statement is "to promote the motorcycling lifestyle and protect the future of motorcycling." The organization was founded in 1924 and as of October 2016 had more than 1,100 chartered clubs. For clubs and promoters it provides guidance and advice on running events and rallies, and allows affiliated members to vote on AMA matters. It also has a corporate membership category with representatives from the US motorcycle industry. The AMA is the official national federation representative (FMN) for the United States of America in the Fédération Internationale de Motocyclisme (FIM), and organizes the US teams and riders for FIM-sanctioned events, including the International Six Day Enduro, Motocross Des Nations and Trials Des Nations. History The AMA was a whites ...
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Circle Of Forces
The circle of forces, traction circle, friction circle, or friction ellipse is a useful way to think about the dynamic interaction between a vehicle's tire and the road surface. The diagram below shows the tire from above, so that the road surface lies in the ''xy''-plane. The vehicle to which the tire is attached is moving in the positive ''y'' direction. In this example, the vehicle would be cornering to the right (i.e. the positive ''x'' direction points to the center of the corner). Note that the plane of rotation of the tire is at an angle to the actual direction that the tire is moving (the positive ''y'' direction). Put differently, rather than being allowed to simply "roll" in the direction that it is "pointing" (in this case, rightwards from the positive ''y'' direction), the tire instead must "slip" in a different direction from that which it is pointing in order to maintain its "forward" motion in the positive ''y'' direction. This difference between the direction the ti ...
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Oversteer
Understeer and oversteer are vehicle dynamics terms used to describe the sensitivity of a vehicle to steering. Oversteer is what occurs when a car turns (steers) by more than the amount commanded by the driver. Conversely, understeer is what occurs when a car steers less than the amount commanded by the driver. Automotive engineers define understeer and oversteer based on changes in steering angle associated with changes in lateral acceleration over a sequence of steady-state circular turning tests. Car and motorsport enthusiasts often use the terminology more generally in magazines and blogs to describe vehicle response to steering in a variety of maneuvers. Vehicle dynamics terminology Standard terminology used to describe understeer and oversteer are defined by the Society of Automotive Engineers (SAE) in document J670SAE International Surface Vehicle Recommended Practice, "Vehicle Dynamics Terminology", SAE Standard J670, Rev. 2008-01-24 and by the International Organization ...
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Normal Force
In mechanics, the normal force F_n is the component of a contact force that is perpendicular to the surface that an object contacts, as in Figure 1. In this instance ''normal'' is used in the geometric sense and means perpendicular, as opposed to the common language use of ''normal'' meaning "ordinary" or "expected". A person standing still on a platform is acted upon by gravity, which would pull them down towards the Earth's core unless there were a countervailing force from the resistance of the platform's molecules, a force which is named the "normal force". The normal force is one type of ground reaction force. If the person stands on a slope and does not sink into the ground or slide downhill, the total ground reaction force can be divided into two components: a normal force perpendicular to the ground and a frictional force parallel to the ground. In another common situation, if an object hits a surface with some speed, and the surface can withstand the impact, the nor ...
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Rallying
Rally is a wide-ranging form of motorsport with various competitive motoring elements such as speed tests (often called ''rally racing),'' navigation tests, or the ability to reach waypoints or a destination at a prescribed time or average speed. Rallies may be short in the form of trials at a single venue, or several thousand miles long in an extreme endurance rally. Depending on the format, rallies may be organised on private or public roads, open or closed to traffic, or off-road in the form of cross country or rally-raid. Competitors can use production vehicles which must be road-legal if being used on open roads or specially built competition vehicles suited to crossing specific terrain. Rallying is typically distinguished from other forms of motorsport by not running directly against other competitors over laps of a circuit, but instead in a point-to-point format in which participants leave at regular intervals from one or more start points. Rally types Road rallies ...
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Drifting (motorsport)
Drifting is a driving technique where the driver intentionally oversteers, with loss of traction, while maintaining control and driving the car through the entirety of a corner. The technique causes the rear slip angle to exceed the front slip angle to such an extent that often the front wheels are pointing in the opposite direction to the turn (e.g. car is turning left, wheels are pointed right or vice versa, also known as opposite lock or counter-steering). Drifting is traditionally done by clutch kicking (where the clutch is rapidly disengaged and re-engaged with the intention of upsetting the grip of the rear wheels), then intentionally oversteering and countersteering. This sense of ''drift'' is not to be confused with the ''four wheel drift'', a classic cornering technique established in Grand Prix and sports car racing. As a motoring discipline, drifting competitions were first popularized in Japan in the 1970s and further popularized by the 1995 manga series '' Initial ...
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Racing Line Traditional Braking With Circular Entry
In sport, racing is a competition of speed, in which competitors try to complete a given task in the shortest amount of time. Typically this involves traversing some distance, but it can be any other task involving speed to reach a specific goal. A race may be run continuously to finish or may be made up of several segments called heats, stages or legs. A heat is usually run over the same course at different times. A stage is a shorter section of a much longer course or a time trial. Early records of races are evident on pottery from ancient Greece, which depicted running men vying for first place. A chariot race is described in Homer's ''Iliad''. Etymology The word ''race'' comes from a Norse word. This Norse word arrived in France during the invading of Normandy and gave the word ''raz'' which means "swift water" in Brittany, as in a mill race; it can be found in "Pointe du Raz" (the most western point of France, in Brittany), and "''raz-de-marée''" (tsunami). The word rac ...
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Handbrake Turn
The handbrake turn (also known as the bootlegger's turn) is a driving technique used to deliberately slide a car sideways, either for the purpose of quickly negotiating a very tight bend, or for turning around well within the vehicle's own turning diameter. Technique The driver starts by using steering input to transfer weight to the outside tires; the handbrake is then used to lock the rear wheels, thus upsetting the adhesion between the tires and the road surface. With practice, the car can be placed accurately by releasing the handbrake and accelerating the vehicle. The technique is used in some forms of motorsport, for example rallying, autotesting, drifting and motorkhana. Many sports cars, especially UK makes such as MG and Triumph, as late as the early 1970s were offered with a fly-off handbrake option for competition purposes—the button on the end of the lever has to be pressed before the brake will lock on, which is the reverse of the normal arrangement—allowing f ...
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Brake Bias
The brake balance or brake bias of a vehicle is the distribution of brake force at the front and rear tires, and may be given as the percentage distributed to the front brakes (e.g. 52%) or as the ratio of front and rear percentages (e.g. 52/48). The braking balance affects the driving characteristics in terms of how fast the vehicle can brake, how the vehicle can take corners, and tire wear. The optimal brake balance can vary between circuits, weather conditions and driving styles. On race cars, the brake balance is often part of the racing setup, and in formula car racing it is regularly adjusted during the course of an entire lap. In some cases, the brake balance may be adjusted to match the traction (grip) of the vehicle during braking, which usually means distributing a greater braking force to the front (for example 55/45). In other cases, it may be desirable for the brake balance to be the more similar at the front and rear (e.g. 50/50) for the tires to last longer, which m ...
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Understeer
Understeer and oversteer are vehicle dynamics terms used to describe the sensitivity of a vehicle to steering. Oversteer is what occurs when a car turns (steers) by more than the amount commanded by the driver. Conversely, understeer is what occurs when a car steers less than the amount commanded by the driver. Automotive engineers define understeer and oversteer based on changes in steering angle associated with changes in lateral acceleration over a sequence of steady-state circular turning tests. Car and motorsport enthusiasts often use the terminology more generally in magazines and blogs to describe vehicle response to steering in a variety of maneuvers. Vehicle dynamics terminology Standard terminology used to describe understeer and oversteer are defined by the Society of Automotive Engineers (SAE) in document J670SAE International Surface Vehicle Recommended Practice, "Vehicle Dynamics Terminology", SAE Standard J670, Rev. 2008-01-24 and by the International Organization ...
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Weight Transfer
Weight transfer and load transfer are two expressions used somewhat confusingly to describe two distinct effects: *the change in load borne by different wheels of even perfectly rigid vehicles during acceleration *the change in center of mass (CoM) location relative to the wheels because of suspension compliance or cargo shifting or sloshing In the automobile industry, weight transfer customarily refers to the change in load borne by different wheels during acceleration. This would be more properly referred to as load transfer, and that is the expression used in the motorcycle industry, while weight transfer on motorcycles, to a lesser extent on automobiles, and cargo movement on either is due to a change in the CoM location relative to the wheels. This article uses this latter pair of definitions. Load transfer In wheeled vehicles, load transfer is the measurable change of load borne by different wheels during acceleration (both longitudinal and lateral). This includes bra ...
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