A bike helmet

The latest development in cycling helmet technology is called WaveCel.

Released in March by Trek Bikes, it’s the newest of several technologies that are supposed to help reduce what are called rotational forces, which contribute to concussions

“Rotational motion is what correlates to how much the brain moves inside the skull,” says Steve Rowson, Ph.D., an assistant professor in the department of biomedical engineering and mechanics at Virginia Tech and lab director of Virginia Tech’s Helmet Lab. “If you can reduce the rotation of the head during impact, that reduces the strain or stretching of the brain, and that reduces the likelihood of injury.”

More on bike Helmets

Although WaveCel is the newest such technology, the most prominent may be the MIPS Brain Protection System, which was first released in a cycling helmet in 2010 and can now be found inside hundreds of different helmets made by companies including Cannondale, Scott, Bell, Trek, and Giro.

So how exactly do these technologies work? Does one outperform the others? And are there other important factors to consider when trying to find the best helmet to protect your brain?

CR spoke with our bike helmet experts as well as Virginia Tech's Rowson and the researchers who helped develop MIPS and WaveCel to see what cyclists should consider when choosing a helmet

Understanding Head Injuries

“Bike helmets were developed to prevent skull fracture,” says Peter Anzalone, senior test project leader for bike helmets at CR.

Helmets are still evaluated by the Consumer Products Safety Commission (CPSC)—and by CR—based on their ability to protect against direct shots to the head. Helmets are generally designed to absorb those linear impacts, which can cause skull fractures and severe brain damage.

Direct-impact shocks to the head certainly cause brain trauma, but there’s now a consensus that rotational forces also play an important role in concussions and other brain injuries—though the exact way each crash affects the brain is not yet understood.

When you fall off your bike, you will almost always hit the ground at an angle, which generates rotational forces alongside the shock of a direct collision with the ground, explains Michael Bottlang, Ph.D., co-founder and director of Legacy Biomechanics Laboratory, where WaveCel was developed.

Though researchers first started to understand that rotational motion influenced the severity of head injuries in the 1940s, it wasn’t until very recently that technology to better protect against these risks started to appear. Now, as worries about the effects of concussions—often described as a “silent epidemic” because of their serious but not immediately apparent consequences—have risen, the importance of better protection has become clear. 

According to Rowson of Virginia Tech’s Helmet Lab, the new WaveCel helmets can effectively reduce rotational forces—but so can other helmets with different anti-rotation technologies. 

The MIPS Brain Protection System, a helmet technology that may help prevent concussions.
The MIPS Brain Protection System allows the helmet to move by 10 to 15 millimeters during a crash, which helps keep some rotational energy from the brain.
Illustration: MIPS

How MIPS and WaveCel Work

MIPS and WaveCel work in different ways to achieve the same goal of reducing rotational force, according to Rowson.

MIPS helmets are built with an internal layer of plastic and other components such as stretchy fabric. During a crash, that layer helps keep the brain from absorbing all the rotational force created at the moment of impact, according to Peter Halldin, Ph.D., a researcher from the Swedish Royal Institute of Technology and chief technical officer and the co-founder of MIPS.

A MIPS-equipped helmet can slide a small amount on impact (about 10 to 15 millimeters in any direction) without pulling the internal layer—and the head—with it.

“We redirect the energy,” Halldin says.

Instead of a sliding component, helmets with WaveCel have an internal layer made of a malleable plastic that forms a sort of three-dimensional mesh. It’s designed to crumple, flex, and glide sideways at the moment of impact, according to Bottlang, functioning like a suspension system to absorb the rotational force from the impact. 

The WaveCel helmet layer, which may help prevent concussions.
During a crash, the WaveCel layer in a helmet is designed to flex, crumple, and glide, absorbing rotational energy.
Photo: WaveCel

How Do MIPS and WaveCel Compare?

One of these technologies isn’t necessarily better than the other, according to Rowson, whose lab has tested both WaveCel and MIPS helmets. They both can help protect the brain, but there are other factors that matter, too.

Part of the issue with comparing different systems, according to Anzalone, is that there’s no one standard agreed-upon way to test helmets against rotational impact. “Product development is way ahead of standards testing,” he says. Because of that, each manufacturer has its own ways of testing a helmet’s ability to absorb these brain-jolting forces.

Researchers affiliated with WaveCel recently published a study that demonstrated that based on how they test helmets, WaveCel systems performed significantly better than helmets with no mechanism for reducing rotational force and better than helmets with what’s known as a slip-clean system for reducing rotational force (a term that describes the system used by MIPS).

But MIPS researchers were unable to replicate those results using the tests they use to evaluate helmets, according to Halldin, the MIPS co-founder.

Virginia Tech’s lab has found that the best MIPS and WaveCel helmets offer comparable levels of protection.

“This is a good example of how you can take different approaches and get similar results in terms of having an excellent performing helmet,” Rowson says.

(CR’s standard helmet testing doesn’t evaluate rotational impacts, but CR has sent MIPS helmets to an external lab and found that this technology does reduce rotational impact when compared with sibling, non-MIPS-equipped helmets. WaveCel helmets are currently being tested by CR, with results slated to be included in our updated bike helmet ratings released later this year.)

Both technologies can help reduce risk for brain injury, according to Rowson, but they’re just one of a number of factors that people should consider when purchasing a new helmet. 

What to Look for in a Bike Helmet

The top-performing helmets in CR’s ratings tend to include some system to reduce rotational force, but different designs can fit better on different people.

Important factors include cost, fit, and comfort, Anzalone says.

Here are five useful tips for your next helmet purchase (for more, check out CR’s bike helmet buying guide)

  1. Consider a helmet with rotational force-reducing tech like MIPS or WaveCel if you can find one that fits your budget. It’s “absolutely worth looking for a helmet that reduces rotational force,” says Anzalone. (Experts say this still applies if you are looking for helmets for something other than cycling.) There’s no downside to these technologies, except that they can usually increase the cost of a helmet. But any helmet will reduce your risk for concussion and brain injury: According to one review of research, helmet-wearing is associated with an almost 70 percent lower risk of serious head injury (and a 50 percent reduced risk of any head injury) in a crash.
  2. Find something comfortable. Whether you are buying a helmet for yourself or your children, remember that the most important thing is actually wearing it. So choose something you or your kids will keep on while riding.
  3. If you fall off your bike and hit your head, get a new helmet as soon as you can. Replace your helmet every five years or immediately after it has been involved in an accident or shows visible signs of damage, like cracking in the foam layer.
  4. Get the right fit. Make sure the helmet fits in a snug but comfortable way, starting as close to the right size as possible and adjusting from there. The front of the helmet should sit a couple finger-widths above your eyebrows.
  5. Adjust the chin strap. Tighten the chin strap to the point that opening your mouth causes the helmet to press down on the top of your head. Follow our step-by-step guide to make sure your helmet fits correctly.

Product Picks

Though CR doesn’t specifically test the efficacy of anti-rotational force technology in our lab, our bike helmet ratings include helmets with these technologies. Here are three that are recommended and receive top marks in impact absorption. 

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Scott Arx Plus

Price: $125

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Bell Draft MIPS

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Inside CR’s Bicycle Helmet Test Lab

On the 'Consumer 101' TV show, Consumer Reports expert John Galeotafiore demonstrates to host Jack Rico how CR tests bike helmets and the correct way cyclists should fit and wear an appropriate helmet.