Abstract: Established a finite element model of bicycle helmets and verified its effectiveness to measure its protective performances to the rider’s head according to the drop test in the European Regulation of EN 1078. A real bicycle accident was reconstructed to study the head fracture and the brain injury in cyclist-tovehicle collisions or in cyclist-to-ground collisions. The results show that if the head contacted with the middle of the windshield, the helmeted and unhelmeted difference of the skull fracture risk is less than 1%, with an Abbreviated Injury Scale (AIS) AIS 2+ brain injury risk reducing 4% in the cyclist-to-vehicle collision. While in the cyclist-to-ground collision, the skull fractures risk is reduced by 92% and the AIS2 + brain injury risk is reduced by 17%. The helmet protective performance against the brain injury risk caused by rotational movement is more insufficient than that against the skull fracture risk.

Key words: bicycle helmets, protective performances, accident reconstruction, cyclist-to-vehicle collisions; cyclist-to-ground collisions, finite element analysis