Lowsider
Encyclopedia
The lowsider or lowside is a type of motorcycle
crash
usually occurring in a turn and caused by a loss of grip between the tires and the road surface. It is most often caused by either locking a wheel due to excessive braking or application of excessive power out of or through the turn. It may also be caused by slippery or loose material (such as oil, water, dirt or gravel) on the road surface.
In the United Kingdom
and Australia
it is referred to as a "lowside" rather than a "lowsider".
occurring in the contact patch
. There is a limited amount of force
the contact patch can transmit before the tire begins to slide. Typically, the forces reduce slightly upon sliding.
When travelling in a curve, the tires provide the centripetal force
needed for the acceleration towards the center of the curve. The capsizing moment provided by the motorcycle lean into the corner is in moment equilibrium with the centripetal forces at the ground when all is working correctly. If, having reached a given lean angle, the centripetal forces are reduced then the motorcycle increases its angle of lean until it touches the road surface, usually unseating the rider in the process.
Lowsides may be caused by exceeding the lateral friction limit - by leaning too far - or by exceeding the combined lateral/longitudinal friction limit - by braking too heavily in the curve, typically on the front wheel but not exclusively.
The name derives from the fact that it is usually the inward side the motorcycle will fall on (or the side that points downward in a curve, the low side).
Riders are usually advised to do a lowsider rather than a highsider if neither can be avoided. The lowsider has the advantage of the motorcycle sliding before the rider, thus not threatening to crush them. As well, a lowsider tends to send the rider sliding across the road rather than slamming them into the road, thus reducing the chances of serious trauma.
Motorcycle
A motorcycle is a single-track, two-wheeled motor vehicle. Motorcycles vary considerably depending on the task for which they are designed, such as long distance travel, navigating congested urban traffic, cruising, sport and racing, or off-road conditions.Motorcycles are one of the most...
crash
Accident
An accident or mishap is an unforeseen and unplanned event or circumstance, often with lack of intention or necessity. It implies a generally negative outcome which may have been avoided or prevented had circumstances leading up to the accident been recognized, and acted upon, prior to its...
usually occurring in a turn and caused by a loss of grip between the tires and the road surface. It is most often caused by either locking a wheel due to excessive braking or application of excessive power out of or through the turn. It may also be caused by slippery or loose material (such as oil, water, dirt or gravel) on the road surface.
In the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
and Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
it is referred to as a "lowside" rather than a "lowsider".
Behaviour leading to a lowsider and physical explanation
All forces occurring between the motorcycle and the road (such as accelerating, decelerating and steering) are transmitted by frictionFriction
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and/or material elements sliding against each other. There are several types of friction:...
occurring in the contact patch
Contact patch
Contact patch is the portion of a vehicle's tire that is in actual contact with the road surface. It is most commonly used in the discussion of pneumatic tires, , where the term is strictly used to describe the portion of the tire’s tread that touches the road surface...
. There is a limited amount of force
Force
In physics, a force is any influence that causes an object to undergo a change in speed, a change in direction, or a change in shape. In other words, a force is that which can cause an object with mass to change its velocity , i.e., to accelerate, or which can cause a flexible object to deform...
the contact patch can transmit before the tire begins to slide. Typically, the forces reduce slightly upon sliding.
When travelling in a curve, the tires provide the centripetal force
Centripetal force
Centripetal force is a force that makes a body follow a curved path: it is always directed orthogonal to the velocity of the body, toward the instantaneous center of curvature of the path. The mathematical description was derived in 1659 by Dutch physicist Christiaan Huygens...
needed for the acceleration towards the center of the curve. The capsizing moment provided by the motorcycle lean into the corner is in moment equilibrium with the centripetal forces at the ground when all is working correctly. If, having reached a given lean angle, the centripetal forces are reduced then the motorcycle increases its angle of lean until it touches the road surface, usually unseating the rider in the process.
Lowsides may be caused by exceeding the lateral friction limit - by leaning too far - or by exceeding the combined lateral/longitudinal friction limit - by braking too heavily in the curve, typically on the front wheel but not exclusively.
The name derives from the fact that it is usually the inward side the motorcycle will fall on (or the side that points downward in a curve, the low side).
Riders are usually advised to do a lowsider rather than a highsider if neither can be avoided. The lowsider has the advantage of the motorcycle sliding before the rider, thus not threatening to crush them. As well, a lowsider tends to send the rider sliding across the road rather than slamming them into the road, thus reducing the chances of serious trauma.