Virginia Tech releases ratings for bicycle helmets
June 26, 2018
The Virginia Tech Helmet Lab has released its first set of ratings for bicycle helmets, representing more than two years of dedicated research by the group that has helped drive innovation in the sports equipment industry with evidence-based, consumer-oriented safety testing.
Each helmet’s score on the familiar five-star scale reflects its ability to reduce head-injury risk. Four helmet models earned all five stars, with the Bontrager Ballista MIPS at the top. Two helmets merited only two stars; the rest fell in the three- or four-star range. The Insurance Institute for Highway Safety funded the project and contributed to the research.
More than a third of Americans rode a bike in the last year. For the helmet lab’s team of injury biomechanics researchers, cycling's increasing popularity made it a natural extension of the work they’ve done for years, developing ways to assess how well protective equipment can prevent head injuries.
“Football and other sports get a lot of media attention because there is a high incidence of injury there. But just because of the sheer number of people who ride bikes, there are actually more concussions and more head injuries from cycling,” said Megan Bland, a doctoral student in the Department of Biomedical Engineering and Mechanics who led the research.
A database maintained by the Consumer Products Safety Commission pegged the number of cycling-related head injuries treated in U.S. emergency rooms every year at more than 80,000, and the number of cycling injuries overall is on the rise. Current data suggest that wearing a helmet reduces a cyclist’s risk of head injury by more than 50 percent. For severe head injuries, the protective benefit is even greater.
But which helmets are most effective? Until now, there hasn’t been a systematic way for consumers to know. Every bike helmet on the market is required to meet a standard related to the impact threshold for exceptionally severe head injuries, like skull fractures. But that standard is pass-fail, and didn’t help cyclists discriminate between hundreds of passing helmets; it also didn’t assess helmet performance during less-severe impacts, which are far more common and can still result in concussions and other injuries.
That’s where the helmet lab stepped in.
The group got their start testing football helmets, releasing the first set of ratings using their five-star framework in 2011. Hockey helmets were added to the program a few years later; for both sports, the researchers have seen an uptick in helmet performance since the ratings have been published. Earlier this year, they released the first ratings for soccer headgear, and other sports are in the works.
For the bicycle helmet project, the Insurance Institute for Highway Safety contributed its expertise in analyzing roadway crashes, in addition to financial support.
“Our goal with these ratings is to give cyclists an evidence-based tool for making informed decisions about how to reduce their risk of injury,” said Steve Rowson, an associate professor of biomedical engineering and mechanics in the College of Engineering and the helmet lab’s director. “In cycling, we saw an opportunity to reach a broad cross-section of the public and bring a new level of safety to an activity with a wide range of other benefits. We also hope manufacturers will use the information to make improvements.”
The helmet lab’s initial set of ratings includes 30 popular adult-size models. To develop the ratings, the research team designed an impact simulator that recreates some of the most common head-impact scenarios on the road.
The helmet lab is full of these impact rigs, customized for each sport in their portfolio. Here’s what it looks like for the bike helmet testing: A helmet-clad dummy headform plummets down a drop tower onto an angled anvil to mimic the oblique angle of most real-world crashes. The anvil’s surface is covered in sandpaper that simulates the friction between a helmet and the road.
As the headform hits the anvil, embedded sensors measure its linear acceleration and rotational velocity, two parameters that help predict head injury risk. From that data, the researchers can calculate how effectively the helmet reduces that risk (compared to not wearing a helmet at all).
Each of the 30 helmet models went through a battery of tests that covered six different impact locations and two impact speeds, all chosen to reflect the circumstances of actual crashes. All that data required 120 individual helmets, subjected to a cumulative 720 impacts.
Even with just 30 models in their original test group, the researchers spotted trends beginning to emerge. Helmet style seems to matter: Road-style helmets — that familiar aerodynamic, vented almond shape — tended to perform better than the rounder, smoother urban-style helmets now becoming increasingly popular.
Another factor improving helmet performance was the presence of a technology called MIPS. MIPS is designed to reduce the rotational forces on the head by creating a low-friction “slip plane” between the helmet’s liner and its shell.
“When the helmet hits the road and sticks due to that high friction, your head actually slides relative to the helmet,” Bland explained. That extra fraction of a second of motion lengthens the impact, making it less abrupt. All four five-star helmets are equipped with MIPS.
Cost didn’t always predict performance: the top-performing Bontrager Ballista MIPS was also near the top of the price bracket at $200, but the $75 Specialized Chamonix MIPS earned five stars, too, and four under-$100 models made it into the four- and five-star categories.
Bland said she hopes that the helmet ratings draw attention to ways to reduce the risk of cycling-related head injuries, whether that’s by switching out a lower-rated helmet for a better one — or just wearing a helmet in the first place. More than half of adults in the U.S. report never wearing a helmet, and more than half of cyclists killed in crashes in 2016 were missing one.
“As more people choose the bicycle as a mode of transportation, better helmet design is one of the tools that can be used to address the increasing number of cycling injuries,” said David Zuby, chief research officer at IIHS and a frequent bike commuter.
Meanwhile, more and more helmets are crashing onto the lab’s anvil; the team is adding more road- and urban-style helmets to their list and expanding into mountain bike and skate/BMX styles. They’re planning to evaluate youth helmets, too.
Bland said she gets asked all the time which helmet she would buy. There is one she has her eye on — but she’s holding out for the next batch of ratings to make a final decision.