Softer Foam in Bicycle Helmets Reduces the Impact Force in a Simulation Model

Objective: This study compared the linear acceleration generated from an impact to a manikin's head wearing an off-the -shelf “standard” bicycle helmet (stdBH) compared to a modified bicycle helmet (modBH) (original foam replaced with softer polyolefin foam).

Methods: Pairs of 5 different bicycle helmets from a wide price range ($20-$90) were tested (standard versus modified). The head impact was simulated by striking the test bicycle helmet placed onto the head of a Century BOB boxing manikin, with a conventional football helmet (4.6 kg additional weight added) swung from a 1.2 meter rope and released from an angle of 45º serially for multiple data points as in Figure 2. The manikin's bicycle helmet was struck by the football helmet in the frontal, left parietal, and occipital locations for 12 trials each. Each of three accelerometers located at the manikin’s forehead, apex of the head, and right ear collected data on linear acceleration in the X, Y, and Z planes.

Results: Mean linear acceleration in G's (9.8 m/sec/sec) was obtained from the three accelerometer locations on the manikin's head for each striking position. The mean linear accelerations across the 5 different helmet pairs are summarized in the graphs (Figure 3). For each of the three striking locations, there were statistically lower striking forces sustained with the modified softer foam bicycle helmet (modBH) compared to the standard bicycle helmet (stdBH). The greatest reductions were observed in the apical accelerometers when the manikin was struck from the occipital and parietal locations.
Conclusion: These results suggest that softer foams in bicycle helmets may reduce injury from bicycle accidents. Further research on this topic can lead to the development of safer and more effective bicycle helmets.