Impact Performance Comparison of Advanced Bicycle Helmets with Dedicated Rotation-Damping Systems

Abstract

Bicycle helmets effectively mitigate skull fractures, but there is increasing concern on their effectiveness in mitigating traumatic brain injury (TBI) caused by rotational head acceleration. Bicycle falls typically involve oblique impacts that induce rotational head acceleration. Recently, bicycle helmet with dedicated rotation-damping systems have been introduced to mitigate rotational head acceleration. This study investigated the impact performance of four helmets with different rotation-damping systems in comparison to a standard bicycle helmet without a rotation-damping system. Impact performance was tested under oblique impact conditions by vertical drops of a helmeted headform onto an oblique anvil at 6.2 m/s impact speed. Helmet performance was quantified in terms of headform kinematics, corresponding TBI risk, and resulting brain strain. Of the four rotationdamping systems, two systems significantly reduced rotational head acceleration, TBI risk, and brain strain compared to the standard bicycle helmet. One system had no significant effect on impact performance compared to control helmets, and one system significantly increase linear and rotational head acceleration by 62 and 61%, respectively. In conclusion, results revealed significant differences in the effectiveness between rotation-damping systems, whereby some rotationdamping systems significantly reduced rotational head acceleration and associated TBI risk.

Impact Performance Comparison of Advanced Snow Sport Helmets with Dedicated Rotation-Damping Systems

“…Results are specific to impacts onto a 45°anvil covered with 80 grid sandpaper for consistency with precedence of prior studies. [5][6][7][8][9][10]17 A pilot study was conducted to explore the effect of sandpaper by impacting six additional Smith Maze helmets onto a 45°a nvil with a polished steel surface without sandpaper at 4.8 and 6.2 m/s at front, side and rear impact locations. Averaged across all impact scenarios, impacts without sandpaper yielded the same linear acceleration, a 9% lower rotational velocity, an 18% lower rotational acceleration, and a 16% lower probability of concussion than impacts with an 80 grid sandpaper.…”

“…12 However, recent advances in helmet design suggest that the effectiveness of helmets may be further improved by targeted mitigation of rotational acceleration of the head. [8][9][10] Brain tissues are highly susceptible to rotational acceleration of the head, which subjects brain tissue to shear forces that can induce diffuse axonal injury. 16,18,22,29 Being incompressible, brain tissue has a high resistance to compressive forces associated with linear acceleration, but a very low resistance to shear forces associated with rotational acceleration.…”

“…For bicycle helmets, several designs with dedicated rotation-damping systems have recently been tested for their ability to mitigate rotational acceleration and associated brain injury risk in comparison to standard helmets without a rotation-damping system. 5,9,10 Results revealed significant differences in the effectiveness between rotation-damping systems, whereby some systems significantly reduced rotational head acceleration compared to standard helmets, while others did not. 10 These bicycle helmet results may not be extrapolated to snow sport helmets, which have fewer vents and an inner comfort liner covering the rotationdamping system that may aid or hinder its effectiveness.…”

A New Assessment of Bicycle Helmets: The Brain Injury Mitigation Effects of New Technologies in Oblique Impacts

“…Limited studies have assessed the performance of bicycle helmets with new technologies dedicated to mitigating rotational head motion. 8 , 9 These previous studies assessed the performance of helmets in a single impact location. In contrast, a significant body of research has shown that the location and direction of impact has a large effect on rotational kinematics of the head and brain deformation.…”

Effectiveness of 2ndSkull Products in Reducing Head Impact in Simulated Sports

“…Preventative headgears made to reduce head injury risk have been tested and implemented on a large scale in professional and semi-professional sports including the National Football League. Special attention has been paid to helmets, with numerous prototypes undergoing rigorous testing to determine models that optimally reduce head impact severity (Bartsch et al, 2012; Bottlang et al, 2020; Viano et al, 2006). While other types of protective headgear have also been evaluated, the scientific consistency and validity have predominantly been reported from those that are helmet based (Sone et al, 2017).…”