Quantifying Effects of Design Features on Youth Bicycle Helmet Performance During Oblique Impacts.

Purpose: Cycling is a leading cause of youth sports-related head injury in the U.S. Although youth bicycle helmets sold in the U.S. comply with safety standards limiting head linear acceleration, there needs to be more information on relative differences in protection between helmets that pass. Additionally, studies have yet to look at quantifying youth bicycle helmet performance with respect to their design.

Methods: Twenty-one youth bicycle helmet models were subjected to oblique impacts at three locations and two impact speeds where peak linear acceleration (PLA) and peak rotational acceleration (PRA) were quantified. Design features were characterized, including expanded polystyrene (EPS) thickness and presence of shell protrusions. A linear mixed model was used to quantify the effects of design features on PLA and PRA.

Results: The youth bicycle helmet models evaluated produced wide ranges in kinematics across all configurations. PLA averaged 95.9 ± 26.1 g at 3.1 m/s and 170.1 ± 43.5 g at 5.2 m/s, while PRA averaged 3150 ± 1275 rad/s² at 3.1 m/s and 4990 ± 1977 rad/s² at 5.2 m/s. Impact location, impact speed, and EPS thickness had strong effects on PLA and PRA, whereas shell protrusions only had strong effects on PLA.

Conclusion: Youth bicycle helmets with thicker EPS, thinner shells, and shell protrusions at impact locations improved the linear and rotational kinematic measures. Limitations include the small sample size and the impacts analyzed not representing all possible real-world scenarios.