Current bicycle helmet standards do not include angular acceleration, for certification even though it is known that it is the dominant cause of brain injury. The objective of this study was to develop an improved test method, including oblique impacts, to evaluate helmets sold on the European market. Four physical tests were conducted, shock absorption with straight perpendicular impact and three oblique impact tests. Computer simulations were made to evaluate injury risk. In total, 17 conventional helmets and one airbag helmet were included. All helmets except five showed a linear acceleration lower than 180 g, which corresponds to a low risk of skull fracture. The airbag helmet performed three times better than the conventional helmets (48 g vs. an average of 175 g). The simulations indicated that the strain in the grey matter of the brain during oblique impacts varied between helmets from 6% to 44%, where 26% corresponds to 50% risk for a concussion. The lowest strain was measured in the brain when the airbag helmet was tested. Helmets equipped with Multidirectional Impact Protection System (MIPS) performed better than the others. However, all helmets need to reduce rotational acceleration more effectively. A helmet that meets the current standards does not necessarily prevent concussion. (Author/publisher)
Abstract