Crash typology of professional cycling crashes.

Mild traumatic brain injury (mTBI) is a frequent but underreported consequence of professional cycling crashes, yet current helmet testing standards primarily simulate head-first impacts, and their representation of real-world head impact scenarios is unclear. This study explores crash typology of professional cycling crashes involving head-ground contact through systematic video analysis of 128 head impacts occurring between 2012 and 2024. Most head impacts occurred during road races (113/128, 88 %) and were associated with multi-cyclist collisions rather than single-cyclist crashes, with topple-over crashes representing the most common mechanism (49 %), followed by skid-outs. Riders predominantly landed front or front-side relative to their direction of travel, with 66 % of impacts occurring in a sideways body posture, and head contact most frequently involved the helmet's side and rim regions (>50 % of impacts). Notably, body-first head impacts dominated the crash profiles (92 %), with the torso or arms contacting the ground before the head, while direct head-first impacts comprised 8 % of cases. Impact severity was distributed relatively evenly across low (30 %), medium (33 %), and high (36 %) categories, with collision-related crashes being more likely to result in high-severity outcomes than non-contact crashes. These findings reveal a potential mismatch between current helmet testing protocols and the predominant mechanisms observed in professional cycling crashes. Video-based analysis provides critical insights into impact mechanisms that are overlooked by traditional injury reporting methods, particularly highlighting the prevalence of body-first impacts and side-rim head impacts. This crash typology may provide a foundation for future biomechanical studies and could support the development of helmet testing methods that better represent real-world cycling impact scenarios.