Impact performance of bicycle helmets.

Seven brands of bicycle helmets were compared by means of a drop test using an instrumented Hodgson-WSU headform, on the front (F), rear (R) and left side (LS) locations from a height of 1.0m and on the right front boss (RFB) from either 1.0m or 1.75m. Acceleration signals from the headform were computer processed to yield peak acceleration and the Gadd Severity Index (GSI). Significant differences between helmets and within helmets at different locations were found. Helmets with crushable polystyrene liners were much superior to those with soft foam liners. The superiority of the polystyrene liners disappeared however when helmets were subjected to two consecutive drops to the same location (R). The results also indicated that for most cases the GSI was between 800-1200 but there were two helmets that had values in excess of 1500. Clearly not all bicycle helmets provide equivalent levels of protection and some are much superior to others.