The testing results, published in the journal Annals of Biomedical Engineering, showed no correlation between price and protection.
The Imperial team tested 30 of the most popular adult helmets on the market, all medium-sized, using a combination of in-lab testing, data from major retailers, and a survey of more than 1,000 cyclists.
All cycle helmets sold, and therefore, all tested in the study must have passed regulatory standards to ensure they offer protection.
Dr. Baker said: “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.
“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.”
She said 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.
The overall risk was calculated as an average of the linear and rotational risks, which assumes they are equally important and present in real-world casualties.
However, the researchers say the risk weighting should be adjusted in the future as more data emerge 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.
Using only medium-sized helmets in this study, which fitted the 57 cm (1.87 feet) (22.4 inches) circumference test head form, means that future work will test a wider range of helmet sizes to ensure equitable research.
Study senior author Dr. Mazdak Ghajari, also from the Dyson School of Design Engineering at Imperial, supervised the research and is also a working group member responsible for one of the European standards on helmet safety.
He said: “The science of brain biomechanics has advanced tremendously and we now know much more about how best to protect the human head from serious injury and injuries with long-term effects in a collision.
“We are sharing our findings with helmet manufacturers and those responsible for setting testing standards, so that the industry can keep pace and develop products that offer the best possible protection.
“Thanks to funding from the Road Safety Trust, our research can now help consumers to make an informed choice when they buy a helmet.
“We believe these ratings will lead to further improvements in helmet designs, providing better protection against a range of head and brain injuries if a cyclist is involved in a fall or collision.”
The Road Safety Trust has extended its funding for three years so that Dr. Ghajari and his team can apply their testing and rating techniques to children’s helmets and continue to test the wide range of adult helmets on the market.
Ruth Purdie, Chief Executive of The Road Safety Trust, said: “In the event of a collision, cycle helmets can play a vital role in preventing and reducing the severity of head injuries.
“That’s why this new rating system is incredibly important.”
She added, “It will show riders which helmets offer the best protection, helping them to make better-informed choices.”
People can check the rating of the adult cycle helmets tested to date on the helmet impact protection effectiveness rating (Hiper) website.
Produced in association with SWNS Talker
