Safety rating system for cycle helmets revealed by new research

Testing on the UK’s 30 most popular helmets, funded by The Road Safety Trust and Innovate UK, revealed significant differences in performance with no link between the price of a helmet and the level of safety it provides the wearer.

The Imperial researchers converted their findings, published in Annals of Biomedical Engineering, into a searchable ‘helmet impact protection effectiveness rating’ (hiper) website.

“Until now, there has been limited information about how well cyclists can expect their helmet to protect them during head impact,” Dr Claire Baker, from Imperial’s Dyson School of Design Engineering and lead author of the study, said in a statement.

“This is because current safety standards are simply pass/fail and only test direct impact sustained during straight-on head impact. However, evidence from previous studies shows that lasting brain damage occurs in more serious impacts or when the head undergoes rapid rotations during an impact.” 

To produce the ranking system, the Imperial team tested 30 of the most popular medium-sized adult helmets on the market, based on a combination of in-lab testing, data from major retailers, and a survey of over 1000 cyclists.   

All cycle helmets sold, and therefore all helmets tested in this study, must have passed regulatory standards to ensure that they do offer protection. 

“All helmets sold in Europe must meet the EN1078 minimum safety standard, but we wanted to determine whether some offered better safety protection than others in realistic collision tests. We developed a simple scoring system to rate helmets based on the risk of head injury during a collision,” said Dr Baker. “The risk of injury took account of the likelihood of deep brain injuries from head rotation as well as more surface level injuries and potential skull fractures from direct impact. Our scoring ranges from zero for lower protection to five for the best on the market. 

“Interestingly, we found no correlation between price and protection, with the highest-performing helmet being one of the less expensive, retailing at around £50. Our new ratings give consumers objective, evidence-based data to support their buying decisions.” 

Evidence from previous studies shows that head rotation is often associated with loss of consciousness and injuries deep in the brain that can be life-changing, for example triggering dementia.   

In the study, the overall risk was calculated as an average of the linear and the rotational risk, which assumes they have equal importance and presence in real-world casualties. However, the researchers said that the weighting of these risks should be adjusted in future as more data emerges on the distribution of these injuries and their consequences.

The survey showed that a large proportion of the adult population of all genders wear medium helmets. The use of only medium-sized helmets in this study, which fitted the 57 cm circumference test headform, means that future work will test a wider range of helmet sizes to ensure equitable research.

The research team said that they are sharing their findings with helmet manufacturers and those responsible for setting testing standards, to ensure that the industry can keep pace and develop products that offer the best possible protection.

The Road Safety Trust has extended its funding for three years so that senior author Dr Mazdak Ghajari – also from the Dyson School of Design Engineering at Imperial – and his team can apply their testing and rating techniques to children’s helmets as well as continuing to test the wide range of adult helmets.