Decelerations of Capsized Motorcycles - An Update 2022-01-0823

Many motorcycle crashes involve the motorcycle capsizing, impacting the ground, and sliding on the road surface. When performing speed calculations, the energy or speed loss for the ground impact and sliding phases may need to be calculated. To perform these calculations, the reconstructionist will typically determine the slide distance based on the physical evidence and then apply a range of decelerations over that distance based on test data in the literature. Decelerations can be selected for motorcycles with similar characteristics (crash bars, panniers, fairings, etc.) sliding on similar surfaces (asphalt, concrete, dirt, gravel, etc.).

This approach is adequate but sometimes results in a wide range due to the variability in reported decelerations in prior studies. It could be helpful to narrow the likely range of decelerations, and thus, the speed range. Many past studies, however, describe their tests with inadequate detail to parse out precisely what factors were most influential in producing the reported decelerations. The present study reports four additional motorcycle drop and slide tests, attempting in the process to lay out a model for how future tests could be reported such that influential factors could be identified. In addition, this test series included a motorcycle with crash bars. This motorcycle was tested twice with the crash bars. Then the crash bars were removed, and the motorcycle was tested again. These tests involved the motorcycle experiencing more significant impacts with the ground than prior tests involving motorcycles with crash bars.