Lowside and highside
In a lowside, the motorcycle falls inward and slides. In a highside, the rear tire loses grip and regains it abruptly, which can throw the rider from the seat.
What is a lowside
When the tire does not have enough traction to hold its line, the motorcycle falls toward the inside of the turn and slides along the road with the rider.
What causes it
- front-wheel slide: braking too sharply while leaned over, excessive lean, or a sudden line change
- rear-wheel slide: opening the throttle too abruptly or locking the rear wheel
- sand, oil, water, lane markings, ice, and other areas where traction suddenly deteriorates
- worn or cold tires, incorrect pressure
Why a highside is usually more dangerous
In a lowside, the motorcycle and rider fall onto their sides and slide along the road. In a highside, traction can return abruptly and throw the rider up and forward. The fall is from a greater height.
How it relates to grip reserve
The more you lean, the less grip reserve remains for braking or throttle. If you brake or open the throttle abruptly at that point, it is easier to break the tire loose.
A lowside is not a way to stop
If danger appears ahead, do not intentionally drop the motorcycle. As long as it is on its wheels, you can brake and change direction. After a fall, it is nearly impossible to control either the motorcycle's slide or your own.
Sources · 1
- Motorcycle Operator Manual
Handling Dangerous Surfaces, pp. 28–30
Used for: Loss of grip while leaned over on a slippery surface.
Open source
How a highside develops
- rear tire loses traction, and the rear of the motorcycle steps out
- motorcycle rotates at an angle to its direction of travel
- rear tire abruptly regains traction
- motorcycle snaps out of the slide and throws the rider off the seat
- rider flies up and forward, often to the side as well
Rear-wheel lockup
If the rear wheel locks in a turn and steps out, abruptly releasing the brake can cause a highside. The tire regains grip on the pavement when the motorcycle is already rotated at an angle to its direction of travel.
The same can happen after a throttle-induced slide
The rear tire can lose grip and spin under acceleration. If the rear has already stepped toward the outside of the turn, abruptly closing the throttle can cause grip to return suddenly and produce a highside.
A highside develops almost instantly
When traction returns abruptly, the rider may be thrown off the seat before they can react. The motorcycle continues moving or tumbling and may hit the rider after the fall.
Sources · 1
- Motorcycle Operator Manual
Crash Avoidance, pp. 26–28
Used for: Sudden regain of rear-wheel grip after a lateral slide can throw the motorcycle up.
Open source
How to reduce lowside risk
Slow down before leaning hard. In a turn, brake, open the throttle, and change your line smoothly. On a slippery surface, reduce speed and lean angle so the tires retain some grip reserve.
One slide, different outcomes
A rear-wheel slide can end in different ways. If the tire keeps sliding, the motorcycle may fall into a lowside. If traction returns abruptly, a highside is possible.
Avoid abrupt actions
- open the throttle smoothly, especially at a large lean angle
- do not lock the rear wheel with abrupt braking
- slow down in advance on a slippery surface
- do not combine a large lean angle with abrupt braking or throttle inputs
- if the rear wheel is already sliding sideways, do not try to make the tire regain traction abruptly. Smoothly reduce throttle or braking force as the motorcycle straightens
When the rear wheel locks and steps out
If the rear has already stepped out, do not release the brake with a sudden jerk out of panic. A sudden return of traction can throw the motorcycle up. It is better to discuss the behavior of a locked rear wheel in advance with an experienced instructor; do not deliberately provoke this kind of slide on the road.
Don't rely on the motorcycle's weight
Even on a heavy motorcycle, the rider can be thrown off the seat when traction returns abruptly.