Causes of accidents

Steering in the opposite direction is required at corner entry and when changing directions in S-curves

In mid-corner at a stable lean angle the bike will steer itself by castor effect

Countersteering is required again at corner exit to reduce lean angle

Countersteering is required to increase or decrease lean angle in every curve

A hypothetical curve with dry asphalt - Braking or reducing throttle reduces ground clearance when corneringGiven the common incidence and serious consequences of motorcycle accidents, there has been surprisingly little study of their causes. The only major work done on this subject in the USA is the Hurt Report, performed around 1980 in the Los Angeles area.

A major cause of motorcycle crashes, especially in rural areas, is the failure of riders to countersteer. Countersteering requires pressing forward on the right handgrip to turn right, and pressing on the left handgrip to turn left. In developed areas, the major cause of crashes is a motorist violating a motorcyclist's right of way, causing a collision.

According to the Hurt Report, speed is not a factor in the majority of crashes:

The path between straight-line motion and free equilibrium turn requires an initial steering motion opposite that of the steady turn. Motorcycle riders in these accidents showed significant collision avoidance problems. Most riders would over brake and skid the rear wheel, and under brake the front when greatly reducing collision avoidance deceleration. The ability to counter steer and swerve was essentially absent. The median pre-crash speed was 29.8 mph (48.0 km/h), and the median crash speed was 21.5 mph (34.6 km/h), and the one-in-a-thousand crash speed is approximately 86 mph (138 km/h).

This is why the Motorcycle Safety Foundation teaches countersteering to all students in all of its schools, as do all motorcycle racing schools. However, countersteering is not taught in driver education classes, nor in science classes. Countersteering is not a question on motorcycle rider "license" tests, which use deceptive language and defective images that falsely appear to show that motorcycles steer just like automobiles.