Why E-Bikes Are Changing The Way We Think About Bicycle Helmet Safety

Why E-Bike Riders Should Be Thinking Beyond the Bicycle Helmet

For years, the bicycle helmet has been treated as a fairly simple bit of safety equipment. Put one on, make sure it fits, and it should protect your head if you come off. But the way we ride is changing.

E-bikes have made cycling faster and more accessible, allowing riders to travel at speeds that would previously have required considerably more effort. In the U.S., Class 3 e-bikes can provide motor assistance up to 28 mph, while even a relatively modest commuter e-bike can make maintaining 20 mph feel almost effortless.

That creates a problem that is easy to overlook. The faster you travel, the more energy is involved when something goes wrong.

It also raises questions about whether the traditional approach to bicycle helmet design is enough.

A helmet is very good at dealing with a direct impact. But crashes rarely happen quite so neatly. A cyclist's head can strike the ground at an angle, creating rotational forces that cause the brain to move inside the skull.

A 2024 study examining 30 popular bicycle helmets found considerable differences in their ability to manage rotational injury risk when subjected to oblique impacts. The researchers found a 4.21-fold difference between the best and worst-performing helmets for rotational injury risk, compared with a 1.76-fold difference for linear injury risk.

In other words, what happens when your head hits the ground isn't necessarily just about how hard it hits.

The problem with rotation

James Cook, CEO and founder of Release Layer System, believes consumers are still underestimating the significance of rotational forces.

"Safety is becoming more relevant as wellness and longevity are trends upwards," he says. "However, the importance of rotational impact leading to brain injuries is underestimated and we believe there is a big opportunity to educate and inform consumers."

There has been progress. Cook says the majority of cycling helmets priced above $70 now incorporate some form of rotational-impact mitigation technology.

One of the best-known examples is MIPS, which allows a degree of movement between the helmet and the rider's head during an angled impact. But RLS takes a rather different approach.

Rather than putting its movement mechanism inside the helmet, RLS sits on the outside.

Enter the HEXR Miden

The HEXR Miden is an urban cycling helmet that uses the Release Layer System to tackle rotational forces.

The technology consists of an outer panel attached to a bearing layer. In a crash, the system is designed to "react, roll and release". The outer panel can move independently of the rest of the helmet, with small bearings allowing it to roll rather than simply sliding against another layer.

The idea is that the outer section takes the hit and redirects some of the rotational energy rather than allowing that energy to be transferred into the rider's head.

"Almost all helmet impacts are angled, which can cause the brain to spin," says Cook. "RLS is designed to address these angled impacts, deflecting energy away from the brain."

It is an unusual sight in a helmet test. Rather than seeing the entire helmet remain intact, the outer panel is deliberately designed to release under the right impact conditions.

"On impact, the top panel disengages from the remainder of the helmet, becoming sacrificial, and deflects energy that would have otherwise gone into the head and caused brain injury," Cook explains.

The apparent destruction is therefore part of the protection strategy.

What happens in a crash?

The distinction between RLS and more conventional systems comes down to where the movement takes place.

MIPS, for example, uses a slip-plane system inside the helmet. RLS moves that mechanism to the outside, using rolling bearings beneath the outer panels. RLS says this allows considerably more movement than conventional slip-plane systems.

"The technology is on the outside and is designed to be sacrificial during impact," says Cook.

That doesn't mean the Miden is designed to fall apart during every minor knock. The system is intended to react to the forces generated during a serious impact.

Independent testing is beginning to provide some evidence that the concept works.

A peer-reviewed study published in the Journal of Biomechanical Engineering in June 2026 tested RLS across urban, road and mountain-bike helmet configurations. Researchers conducted 96 oblique impact tests across different helmet types, impact locations and headforms. RLS-equipped helmets reduced peak angular velocity by between 57% and 66% compared with equivalent conventional helmets.

That matters because angular velocity is one of the measurements used to assess the rotational movement of the head during an impact. Cook says this is one of the most important metrics to watch.

"An important metric to reduce is the rotational velocity, rads/s, because it can be directly linked to the likelihood of concussion," he says. "RLS was found to reduce rotational velocity by 66% and the likelihood of concussion by over four times."

The study itself reported a 68–86% reduction in the estimated probability of an AIS2+ brain injury under its tested conditions.

That qualification is important. Laboratory testing cannot recreate every crash a cyclist might experience, and no helmet can guarantee that a rider will avoid a concussion or traumatic brain injury.

But the results do suggest that rotational protection deserves considerably more attention than it has traditionally received.

Why it matters for e-bikes

This is particularly relevant to e-bike riders.

A conventional cyclist may spend much of a journey travelling at relatively modest speeds. An e-bike can make 20 mph cruising almost mundane. Faster Class 3 machines can push towards 28 mph, and riders can maintain those speeds with considerably less physical effort.

At those velocities, a collision with a vehicle, curb or road surface can become a serious event very quickly.

That doesn't mean every e-bike rider needs to buy the most expensive helmet available. Fit, certification, condition and correct use remain fundamental. A badly fitted premium helmet is still a badly fitted helmet.

But the Miden illustrates how helmet design is beginning to move beyond simply putting more material between a rider's skull and the road.

The HEXR Miden currently sits at the top of Virginia Tech's urban helmet rankings, according to RLS, while RLS-equipped helmets occupy the top two positions in the overall rankings at the time of writing.

There is also the question of longevity. Cook says RLS is not intended to shorten the normal lifespan of a helmet.

"It shouldn't affect the typical 3–5 year lifespan of a helmet," he says. "We test our technology across extreme climates to ensure the product is durable."

And then there is the golden rule of helmet ownership: replace it after a crash.

"Helmets are designed for a single impact," Cook says. "We would always recommend to replace your helmet after a blow to ensure the helmet isn't compromised."

That advice applies regardless of whether a helmet uses RLS, MIPS or no rotational technology at all.

The bigger change is cultural. As e-bikes continue to make higher-speed cycling commonplace, helmet safety is becoming less about simply surviving a direct blow and more about understanding what happens to the brain during a crash.

The HEXR Miden's Release Layer System is one attempt to address that problem in a radically different way. Instead of trying to keep every part of the helmet together, it deliberately allows part of it to move, roll and ultimately release. It sounds counterintuitive.

But when the thing you're trying to protect is the brain, deliberately sacrificing a piece of the helmet may be a considerably better outcome than allowing that energy to reach the person wearing it.

This article was originally published on Forbes.com