Evaluating the safety of small-wheeled micro-mobility devices: A design-agnostic, performance-based experimental approach

Abstract

With the rise of electric micro-mobility devices like e-scooters and e-bikes, accidents and injuries are becoming increasingly common worldwide. Therefore, there is a pressing need for an in-depth analysis of the possible risk factors to improve the safety of the riders and the surroundings. Adopting a systematic approach, we designed five experiments focusing on self-stability, handling, acceleration, braking, and obstacle interaction, considering common causes of accidents and representing different riding scenarios. In this study, we experimentally investigated the dynamic performance and safety considerations of small-wheel (<20 in.), lightweight (<20 kg), and compact (800–900 m) micro-mobility devices, encompassing Power Assisted Bicycles (PABs) and Personal Mobility Devices (PMDs). A total of eight devices, including four PABs (e-bikes) and PMDs (e-scooters) with different wheel sizes, braking types, operating voltages, motor ratings, and two mechanical bicycles, were selected for the study. Results highlight that compact small-wheel PABs and PMDs exhibit reduced stability compared to larger-wheeled counterparts, indicating that their design is not well optimized. The study also highlighted risks associated with hand signals and obstacle interactions for these devices. Moreover, the study also investigates the effect of higher voltage batteries together with higher motor ratings on safety. The study recommends key measures, such as optimizing frame design, adopting a minimum wheel size of 14 in., regulating voltage and motor power, and introducing features like turning lights, mirrors, and front suspension to enhance safety. These insights contribute valuable recommendations for designing and regulating small-wheel micro-mobility devices to mitigate accidents and promote safer transportation practices.