Substandard impact performance of common bicycle helmets

DeMarco AL, Chimich DD, Bonin SJ, Siegmund GP (2018). Substandard impact performance of common bicycle helmets. Brain Injury Across the Age Spectrum: Improving Outcomes for Children and Adults Conference, The Journal of Head Trauma Rehabilitation, 33(3), pp. E87-E88. doi: 10.1097/HTR.0000000000000401.

Bicycling generates more emergency department treatments for traumatic brain injuries in children and adolescents than all other sport/recreational activities (Gilchrist, 2011). Bicycle helmets sold in the US must be certified to the Consumer Product Safety Commission (CPSC, 1998) standard requiring peak headform accelerations of <300g for impacts above a prescribed “test line”. The test line is used to define the region of the helmet that is subject to testing. This region includes the cephalad portion of the helmet, but typically does not include the helmet’s lower edge and thus does not cover the location of many real-world impacts we see in our forensic work. The CPSC standard is self-certifying, which means manufacturers test and certify their own helmets. As a result, compliance data are not publicly available.

Our goal was to investigate the impact performance of CPSC-certified bicycle helmets at impact locations below, on and above the test line to determine how impact performance declines below the test line. We tested 12 popular helmet models including kids helmets (MEC Dash, Stoneridge Dora), traditional vented helmets (Bell Adrenaline, Giro Revel, Smith Overtake, POC Octal Raceday, Fox Flux) and hard-shell BMX style helmets (Bell HUB, Bern Macon EPS, Schwinn Pharos, Bell Trans, Nutcase Street Gen 3). Impact locations were chosen based on each helmet’s geometry and were located on and in increments of about ±1.5cm from the test line on the front, side and rear of the helmets. Ten to 28 impacts were conducted per model with each helmet subjected to 1 to 3 impacts. Peak headform linear acceleration was measured.

Across all 181 impacts, the helmets generally had higher accelerations for impacts near the lower edge compared to more cephalad regions. At and above the test line, half of the helmet models (Bell Adrenaline, Smith Overtake, Fox Flux, Bern Macon EPS, Schwinn Pharos, Bell Trans) exceeded 300g (range 306 to 916g) for between 1 and 15 impacts per model. All but one model (Nutcase Street Gen 3) exceeded 300g in at least one impact at any location. Most helmets exceeded 300g because of inadequate energy absorbing liners, inadequate retention systems, or features (e.g., rivets) that directly contacted and dented the headform.

We found that half of the helmets failed to meet the CPSC standard at or above the test line. While more tests are needed across a wider range of helmets, our data suggest that many popular bicycle helmets do not meet the standard and therefore may be exposing bicyclists to an increased risk of head and brain injuries.

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Substandard impact performance of common bicycle helmets