Motorcycle Rider Trajectory in Pitch-Over Brake Applications and Impacts

Abstract

This paper describes how pitch-over events are common in motorcycle accidents, and can be caused by impact to the front wheel and occasionally by hard brake application. In either case, the rider of the motorcycle can be propelled over the handlebars as the motorcycle pitches rear-end up. In accidents caused by pitch-over braking, the accident investigator may be faced with limited evidence and then must rely on analyzing the throw distance of the rider in attempting to reconstruct the pre-accident speed of the motorcycle. This analysis can be complicated by the presence of a second rider (the passenger) on the motorcycle. Pitch over caused by front wheel impact can be similarly complex. Although motorcycle deformation as a result of front wheel impact has been studied, circumstances surrounding the nature of the deformation, or the impact itself, may require that the trajectory of the rider be analyzed in order to determine the pre-impact motorcycle speed. A series of sled tests was conducted to analyze rider and passenger motion during pitch-over events to develop a more complete understanding of how deceleration and initial speed affect the occupant trajectory and velocity. Brake stops were simulated on the sled as well as front wheel impacts. A full-scale crash test was also conducted and compared against the results of the sled simulations. High-speed video footage was analyzed to develop an understanding of the pitch-over dynamics as well as rider/passenger trajectories and velocities. This paper presents the results of this study and offers a method for accident reconstructionists to employ as they examine motorcycle accidents that involve pitch-over events.