Modern bicycle helmets often come with numerous claims. Given that many premium options are designed for bike racing, these options are often performance-related. The best bike helmets claim to be more aerodynamic or have better ventilation, and they’re certainly getting lighter, but are they safer?
When you buy a helmet, it’s reasonable to assume that it’s fit for purpose. All helmets sold by legitimate retailers will pass the safety standards of the specific country in which they are sold. In the US this is the SNELL standard, while in the UK and Europe it’s EN 1078 and you’ll see a sticker on the helmet to verify that it meets the requirements.
But considering these standards haven’t been updated in 25 years, are they still enough to prove that the helmets we buy are safe? I asked Dr. Mazdak Ghajari, principal investigator of UCL’s HEAD Lab project, which tests numerous bicycle helmets as part of its research in an effort to provide consumers with deeper data, whether current standards are adequate.
“The standards ensure that helmets meet a minimum level of protection. Traditionally, they are designed to protect against certain injuries, primarily skull fractures. Therefore, a helmet that meets the standard provides a minimum level of protection compared to a helmet that does not meet the standard,” he said
“Current standards measure helmet protection when hit by a ‘rigid’ flat or non-flat (hemispherical or kerb) anvil. Their pass/fail depends on the risk of skull fracture. Therefore, current helmets may provide good protection , to prevent skull fractures and associated focal brain injuries (such as contusions).”
Three anvils used in helmet testing
(Image credit: Future (Jo Baker))
But a skull fracture isn’t the only potential head injury that can result from falling off a bike. So are these standard approaches a little too narrow? Dr. Gajari believes so.
“These standards do not test whether helmets can reduce the rotational effects of an impact on the brain. Rotation of the head can cause injuries such as diffuse axonal damage, which can have long-term effects and is often more difficult than focal brain injuries therapy,” he said.
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Of course, helmet manufacturers can design products beyond the necessary requirements to meet these standards. It is here that we see the creation of technology designed to minimize the effects of rotation mentioned by Dr. Ghajari, namely MIPS [Multi-directional Impact Protection System] is the easiest to identify. As a non-proprietary design, it appears in many helmets from many brands. But what exactly does rotational impact mean? Why has it gained so much attention over the past few years?
“Head impacts produce different mechanical effects on the head. They can exert direct forces on the head, which may cause skull fractures. These effects are usually assessed by measuring “linear acceleration” at the center of mass of the head. Here’s why Current standards for measuring peak linear acceleration are known to assess the risk of skull fracture,” he said.
“But head impacts also produce head rotation. Head rotation can produce shearing of brain tissue, leading to bleeding and axonal damage.” Axonal injury is a tear in the brain’s nerve fibers, usually caused by the brain being inside the skull during an accident caused by movement and rotation.
(Image source: Future)
Dr. Ghajari explains that any impact can cause both linear and rotational movement of the head, but some impacts can produce greater rotations. An example is an oblique impact, where the direction of motion is at an angle to the direction of impact. “Because they [oblique impacts] Generating huge forces tangential to the helmet, they tend to increase helmet/head rotation,” he said.
So could MIPS technology (or something similar) make helmets safer?
“Using technology that specifically reduces head rotation during impact can help improve helmet protection,” Dr. Ghajari said. “For example, technology that allows for greater relative rotation between the head and helmet can help reduce head rotation, and MIPS has been effective in laboratory experiments at reducing head rotation during oblique impacts.”
(Image source: MIP)
While MIPS has been shown to improve helmet safety in terms of reducing head rotation, it has been incorporated into a design that remains largely unchanged from the past five or even ten years. Bicycle helmets continue to use a fairly standardized design – a shell made of hard plastic, a liner made of foam, an internal adjustable “cage” that allows the helmet to be tightened, and a chin strap. This begs the question whether this blueprint is still the best approach from a security perspective. I asked Dr. Gajari again what he thought
“In my opinion, it’s a good design from a safety perspective,” he said. “The outer shell provides some protection against sharp objects and spreads contact forces over a larger area of the liner. This helps engage a greater volume of liner, thereby increasing energy absorption. The adjustable cage system is essential to ensure the helmet stays in place Head and not falling off before impact is very useful. ”
The “blueprint” of a hard shell, internal foam liner, and chin strap remains the standard approach to safety helmets.
(Image credit: Michelle Arthurs Brennan)
This is encouraging news, especially coming from the leader of a study that tested some 30 helmets to provide consumers with detailed, independent information about helmet safety (you can found results) hiperhelmets.org). But that’s not to say that the design can’t improve and helmets won’t continue to evolve. For example, Trek currently has a patent filed for a helmet design that uses a “sliding energy transfer layer” that also acts as the outer shell of the helmet.
Dr. Gharaji acknowledged that current linear and rotational impact protection could be improved, given that cyclists still suffer brain injuries after falls and collisions, most likely due to changes in materials. As long as it proves to be a good deal.
“There have been some efforts to incorporate new materials into helmet liners to improve head protection, but these materials have largely failed to make it to market due to marginal improvement or high cost,” he said. “I would like to see The use of new materials in helmets can improve their protective properties without having a big impact on the price of the helmet.”
This is a valid point and integral to the continued development of safer helmets. Helmets need to be wearable and removing barriers to use is an important factor, whether making them cheaper, lighter or easier to carry, such as the foldable Newlane design.
Newlane helmet is foldable and portable
(Image source: Newlane)
I’ve always preferred helmets that feel light on my head and have unsurprisingly found them to be more durable than heavier helmets. This is the calling card of many road helmets, which tout ventilation and overall light weight. But I wonder if these modern lightweight designs are less safe even though they are more ideal?
“To improve ventilation, holes have been incorporated into the helmet design, which means more lining is removed, thereby reducing the amount of lining available for energy absorption,” Dr. Gharaji said.
Another recent advancement in helmet design is the incorporation of aerodynamic features. Again I would be interested to know if this would adversely affect the safety of the helmet?
A well-ventilated helmet means cooler head temperatures but less foam lining
(Image credit: Taylor Boucher)
“Aerodynamics and ventilation impose limitations on helmet design from a protection standpoint,” Dr. Ghajari said. “Aerodynamic helmets are thinner, but the thinner the helmet, the less padding is available to absorb energy. There may be smarter ways to design helmets for better aerodynamics and ventilation, which include removing some of the padding Pads, but in a way that helps better protect against certain injury mechanisms, such as rotational mechanisms,” he added.
“The current main approach to improving aerodynamics and ventilation is to make helmets thinner and have holes in the lining,” Dr. Ghajari concluded.
Trek Ballista helmet shape with modern aerodynamic design
(Image credit: Charlotte Broughton)
Of course, this doesn’t make an aerodynamic or lightweight helmet unsafe, but making the helmet thinner or adding vents (which requires removing areas of the lining) will make it more challenging to improve safety. This is where thorough, independent testing that considers real-world impacts can help solidify consumer confidence.
to some extent Virginia Tech Ratingswhich provides comparable results across a variety of helmets and is provided entirely without any funding or influence from the helmet brand. However, a quick scan of the more than 250 helmets tested to date shows that many of them reach five stars. While this is encouraging for helmet safety, it could illustrate the need to continue to advance testing, as Dr. Gharaji and his team are doing, which in turn requires helmet designers to continue to evolve if their Products will receive the highest safety ratings.
