The effectiveness of bike helmets in protecting against brain injuries caused by collisions at speed has been tested for the first time.
New helmet technologies have emerged in recent years to mitigate the instances and severity of traumatic brain injury (TBI) in collisions from cycling, but the way this is traditionally tested leaves room for doubt in their findings.
The majority of real-world cycling-based TBIs are caused by rotational forces on the brain, which are generated by the head hitting the ground at an oblique angle, mostly seen when cyclists fall or collide while moving.
However, current methods test whether heads are protected from falls at right-angles, which happen mostly when bikes are stationary, and do not account for the rotational forces at play when cyclists fall to the ground at speed.
Now, a new Imperial College London paper has demonstrated a new simulation-enabled helmet testing technique that tests how well helmets protect heads from rotational forces.
Testing 27 different helmets in a purpose-built rig at Research Institutes of Sweden, the project found that newer technologies reduced whole-brain strain compared with older helmets.
However, they also found that the effectiveness of newer helmets depended on their technology and location of impact – some helmets which were designed specifically to reduce rotational forces didn’t appear to accomplish their aims.
Its findings could be significant in ensuring future safety innovations in cycling helmets, the research team said.
“The amount of people cycling since the COVID-19 pandemic began has doubled on weekdays and trebled on weekends in parts of the UK,” says lead author Fady Abayazid, of Imperial’s Dyson School of Design Engineering.
“To keep themselves safe, it’s important cyclists know the best way to protect their heads should they have a fall or collision.
“Cyclists falling from motion will most often hit the ground at a non-right-angle. These angles produce rotational forces that subject the brain to twisting and shearing forces – factors contributing to severe TBIs, which can be life-altering.
“However, current testing standards for bike helmets don’t account for this issue, so we designed a new analysis method to address this gap by combining experimental oblique impacts with a highly detailed computational model of the human brain.”
Senior author Dr Mazdak Ghajari, also of Imperial’s Dyson School of Design Engineering, adds: “With cycling’s popularity soaring, we are seeing more requests from the public and cycling communities for a thorough review of new helmet technologies to inform their purchases.
“However, this is hard to do without testing that accounts for rotational forces.
“Our research could help to address this gap, inform customers, improve safety, and reduce the frequency and severity of TBIs from cycling.”
The authors are now looking into testing standards for motorbike and industrial helmets and the Dyson School of Design Engineering has also just built its own rig to carry out future experimental helmet impact tests.
