Epidemiology of Bicycle Crashes in Japanese Core Regional City: Characteristics of Single- and Multiple-Rider Bicycle Crashes

Background/Objectives: Comprehensive epidemiological studies of bicycle crashes involving all ages in Japan are limited, particularly regarding multiple-rider incidents. This study investigated the epidemiology of single- and multiple-rider bicycle crashes in a Japanese core regional city. Methods: Ambulance transport data from Takatsuki City (1 January 2014 to 31 July 2024) were retrospectively analyzed, including demographics, crash characteristics, and severity of injury for bicycle crash patients. The primary outcome was examination of the epidemiology of bicycle crashes with moderate and severe severity or severe and fatal severity, encompassing both single- and multiple-rider incidents. Statistical tests and logistic regression analysis were used. Results: For 6683 transported patients, 6377 (95.4%) involved single-rider crashes and 306 (4.6%) involved multiple riders. Single-rider crash patients were older and more often male. Moderate or greater injuries occurred in 625 single-rider and 11 multiple-rider crash patients. No severe or fatal injuries occurred in multiple-rider crashes. General roadways and intersections were common crash locations. Male sex and older age predicted greater injury severity in single-rider crashes. Fifty single-rider bicycle crashes resulted in severe or greater severity injuries, and four fatal crashes were recorded. Conclusions: This study uniquely details multiple-rider bicycle crashes in Japan, revealing a lower severity of injuries compared to single-rider crashes.