An exponential increase in e-bike injuries in California

Abstract

Background: Electric bicycle (e-bike) sales are growing exponentially worldwide. These vehicles are faster and heavier, with younger riders using e-bikes more frequently, reports of inconsistent helmet use, and increased deaths and injuries. We hypothesized that California has experienced significant annual increases in e-bike rider injuries and injury severity compared with injured traditional bicyclists, using a transportation injury registry and geospatial mapping system, including socioeconomic factors. Methods: We conducted a retrospective analysis of the California Highway Patrol Statewide Integrated Traffic Records System (SWITRS) from 2018 to 2024, identifying e-bike collisions through reporter coding and vehicle brand names. We analyzed demographics, injury severity, fault status, traffic violations, and scene census tract Social Vulnerability Index (SVI). All non-e-bike traditional bicycle collisions served as the comparison group. Results: We identified 4035 e-bike and 58 332 bicycle collisions. E-bike injuries increased sharply over the study period, from two incidents in 2018 to 1566 in 2024 (p<0.001), while bicycle collisions remained stable. E-bike riders were younger (median 33 vs 36 years; p<0.001), with a significantly greater proportion aged ≤14 years (15.6% vs 10.2%). Moderate-to-severe injuries were more common among e-bike riders (15.8% vs 11.9%; p<0.001). Although overall mortality was similar (2.0% vs 1.7%), a significant divergence emerged in 2024, with higher e-bike mortality (p=0.027) and a significant interaction between year and vehicle type. E-bike collisions demonstrated more unsafe speed and improper turning violations and occurred in census tracts with lower social vulnerability. Spatial analysis showed tighter clustering of e-bike collisions relative to bicycles. Conclusions: E-bike injuries are rapidly increasing in California and are associated with a higher severity of injuries compared with traditional bicycles. Urgent efforts are needed for targeted prevention, regulatory alignment, and rider education. Level of evidence: Level III, retrospective case-control study.