It’s remarkable how fast the helmet flies. Fired from a tall drop rig, it travels at over 20km/h and before I’ve had the chance to register what’s happening, it ricochets off an angled surface and disappears into a wooden box.
The 2m-tall drop rig is at Imperial College London’s HEAD Lab, which is on a mission to make finding the safest cycling helmet possible an easier task, through testing that conforms to the latest standards and the lab’s publicly available rating system, Hiper.
Founded by Dr Mazdak Ghajari, with the assistance of four postdoctoral researchers and four PhD students, HEAD Lab conducts research into the effect of impacts on the brain, in collaboration with neuroscientists at Imperial.
Its research into bicycle helmets – alongside hard hats, motorcycle helmets and even rugby scrum caps – focuses on developing test methods that represent real-world scenarios and predict the risk of brain injury.
Short for Human Experience, Analysis and Design, HEAD Lab also worked closely with Ventete to help the startup brand develop the aH-1 inflatable helmet, which was released last year.
Firing helmets from a drop rig
Built during the Covid-19 pandemic, HEAD Lab’s drop rig fires bicycle helmets at 6.5m/s at a small, angled spike that replicates the kind of oblique impacts you’ll likely have if you crash your bike.
“We found that oblique angles are more representative of what happens to cyclists if they have an accident,” says Ghajari, who has worked at Imperial for 17 years researching brain biomechanics.
The risk of oblique impacts is something the helmet safety technology company MIPS has long highlighted.
Ghajari says existing safety standards don’t account for these oblique impacts. “The standards have been measuring linear motion of the head, which essentially measures the risk of skull fractures,” he adds.
“But there is a lot of evidence to show that rotation also produces brain injuries. These injuries are often quite complicated. They can cause long-term effects and even trigger dementia.”
Tension in the industry
Ghajari says there is tension between manufacturers and those arguing for a new helmet standard.
“There is a lot of opposition from the manufacturers' side,” he says, because they have invested time and money “to optimise their helmets for the current standard.”
An updated standard could mean helmet manufacturers will have to invest again, or end up with products that no longer pass the tests.
This could happen fairly soon. The new EN17950 helmet testing standard was approved last year and it’s slated to inform the revision of the long-standing EN1078 standard. This revision will make testing for rotational impacts mandatory and should enhance helmet safety.
Ghajari was involved in developing new headforms for the standard as part of a European Union working group, which also includes Madelen Fahlstedt, a biomechanical specialist at MIPS.
Ghajari says the previous headforms used in helmet testing were good for measuring linear injuries, but not rotational impacts. “The shape’s a bit artificial,” he says.
The new headforms, which HEAD Lab already uses to test helmets, are based on medical images of heads to improve the biofidelity, or how closely they resemble human heads. “I really believe that this is the most biofidelic headform now,” says Ghajari.
Packed with sensors to record the effects of impacts, these headforms are also available in a wider range of sizes, and better reflect the mass and friction of real heads.
The Hiper helmet rating system
The possibility of new standards has led some manufacturers to develop their own testing methods, which Ghajari says aren’t necessarily proven by research or regulated.
“[Manufacturers can] claim that 'My helmet is now 50 per cent better than somebody else's’. But I think that's really confusing for consumers,” he says.
To counter this confusion, last year HEAD Lab launched Hiper (Helmet impact protection effectiveness rating). This is a cycle helmet rating system, which scores helmets out of five for safety, based on the lab’s testing and research into real-world incidents.
A helmet’s overall score combines a variety of tests, which use the EN17950 headforms.
The results are presented on Hiper’s website, which has had more than 100,000 views since it launched in September 2024, alongside videos of the drop rig tests.
Funded by the Road Safety Trust, Hiper has tested 30 helmets so far. After conducting a survey of 1,100 people and research into best-sellers, they chose helmets that reflect a range of price points.
Ghajari says the research group at Imperial wanted to establish whether an expensive helmet is more protective than cheaper options.
The answer? No, an expensive helmet is not necessarily more protective. The Specialized Tactic MIPS scored the highest in HEAD Lab’s testing but is half the price of some of the other helmets it dropped from its rig. Even the cheapest helmet on test scored higher than some pricier models.
William Dawber, a postdoc researcher at HEAD Lab, says Hiper initially tested 30 helmets because they won’t accept helmets directly from a manufacturer. This is to avoid manufacturers potentially modifying the samples, which means the Hiper team has to go and buy the helmets from shops.
“The problem with that is it’s quite costly. But we’ve secured the funding to do another round of 30 helmets this summer,” he says.
Dawber says that for the next round of testing, they want to expand the remit of helmets to include more experimental designs, “so while we're appealing to the public and what they might use, we're also looking at potential innovation for the future,” he says.
The lab also intends to test children’s helmets. Ghajari, a parent, says: “I really find it difficult to find a suitable helmet for my children, because there's no information to tell me if this helmet is better than the others.”
Hiper's top-five rated helmets
| Helmet | Rating |
| Specialized Tactic MIPS | 4.84 |
| Specialized Align MIPS | 4.76 |
| Specialized Echelon II MIPS | 4.68 |
| Lazer Tonic MIPS | 3.82 |
| Bontrager Velocis MIPS | 3.74 |
Deeper impact protection
One helmet that wasn’t included in Hiper’s initial round of 30 but has received lots of attention from the team at Imperial is the Ventete aH-1.
Developed by a team of former architects, the inflatable helmet originally started as a mechanical challenge to have something go from a 2D to 3D shape. The result is a helmet that you can inflate via a Presta valve with an electric pump that’s included in the £350 asking price. This, in theory, makes the helmet easier to carry around and suited to commuters or those using rentals, such as Lime bikes.
Ventete approached HEAD Lab several years ago for assistance. Initially, Ghajari had concerns that an inflated helmet would ‘bottom out’ quickly on impact. But he says that pressurised air could in fact offer deeper impact protection than the foam used in conventional bike helmets.
Testing by the lab shows that it mitigates linear and rotational impacts significantly better than foam helmets. Ghajari says: “The overall linear risk compared to the best performing helmets that we tested here is reduced by 44 per cent.”
“It just shows that air has so much potential in making improvements in reducing injuries in general,” he adds.
Sam Davies, head of design innovation at Ventete, says: “It's really helpful as a manufacturer to be able to have this kind of relationship with specialists.”
Ultimately, the work HEAD Lab has done with Ventete reflects the research group’s mission to keep people safe. Ghajari says the lab stays away from debates around whether people should wear helmets while cycling, but he’s quite clear that wearing a helmet is safer than going without. “It’s proven,” he says definitively.
“We are really trying to help those who choose to wear a helmet to make an informed decision. That is our role, that is really our principle,” Ghajari adds.
