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Virginia Tech and IIHS rate bike helmets on safety

Published June 26, 2018
Updated with comment from Giro.

BLACKSBURG, Va. (BRAIN) — Virginia Tech and the Insurance Institute for Highway Safety have collaborated on a bike helmet rating system based on its own laboratory testing.

The program tested 30 adult helmets, looking at road-style models and urban style models and rating them from one star to five stars. Four earned the highest rating of 5 stars, two earned 2 stars, and the rest were in the 3-4-star range. Of the four 5-star helmets in the initial test group, all are equipped with a Multi-Directional Impact Protection System (MIPS). This technology creates a low-friction layer inside the helmet.

"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, director of the Virginia Tech Helmet Lab and an associate professor of biomedical engineering and mechanics. "We also hope manufacturers will use the information to make improvements."

All the helmets passed CPSC standards. The Virginia Tech and IIHS program said it developed its own "more realistic" testing protocol. The Virginia Tech Helmet Lab currently rates football and hockey helmets, as well as soccer headgear.

"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," Rowson says.

The CPSC requires helmets to prevent head impact accelerations over 300 g, a level associated with skull fracture or severe brain injury. However the CPSC standard does not assess a helmet's performance at lower level impact forces that could still result in a concussion. The group also said CPSC testing doesn't evaluate the entirety of the helmet.

"For instance, the helmet rim is excluded from CPSC testing, even though studies of bicycle crashes have found that a large number of cyclist head impacts are at the helmet rim, often at the sides or front of helmets. In addition, the CPSC testing requires helmets to be dropped perpendicular to the impact surface. In contrast, a bicyclist's head is more likely to strike the pavement at an angle during a crash. Finally, the speed at which the helmet hits the anvil in the CPSC testing represents an extremely severe impact that isn't typical of most bike crashes," the group said in a press statement Tuesday.

Before developing their test protocol, the Virginia Tech researchers conducted two studies with IIHS support. In the first one, they used the CPSC rig to test a group of helmets at two locations — one at the side of the helmet, within the CPSC test area, and one at the front rim, which isn't subject to the required testing. They found that on certain models, the rim location was more vulnerable.

The second study used a different test rig with a more realistic dummy head hitting a slanted anvil, covered with 80-grit sandpaper to approximate the roughness of asphalt. These tests were designed to replicate more accurately the angle at which a bicyclist's head is likely to strike the pavement in a crash.

The rig with the slanted anvil and more realistic head did a better job teasing out differences among helmets, the researchers found. A slightly modified version of that rig is being used for the ratings.

For the ratings, the lab tests each helmet at six commonly impacted locations, including two at the rim. Helmets are dropped on the anvil at two speeds taken from studies of real-world crashes — the median speed at which a rider's head is estimated to hit the ground and a higher speed equivalent to the 90th-percentile speed in the real-world crash studies.

Sensors embedded in the headform measure linear acceleration and rotational velocity, and the risk of concussion is estimated from those measurements. The number of stars assigned to each helmet represents how effectively that model reduces overall injury risk.

In general, the test found that road helmets tended to perform better on its test than urban helmets.

The lab is continuing to test more adult helmets of different styles, including mountain bike and skate/BMX helmets, and will update its website as new ratings are released. Evaluations of youth helmets also are planned.

More information: Ratings of the first 30 helmets tested.

Giro's Thom Parks, the brand's senior director of product safety, said he applauded Virginia Tech's effort.

"Virginia Tech's Cycling STAR rating is another tool that can help us understand the performance of our products and the potential for helmets to reduce risk of traumatic brain injuries, including concussions," Parks said. "The testing and ratings represent a single methodology based on Virginia Tech's point of view and their available resources for testing cycling helmets, and we believe the Cycling STAR ratings can be complimentary to the research and testing we do in the Dome as part of helmet creation at Giro.

"We applaud Virginia Tech for applying a STAR rating system to cycling helmets. We are also encouraged to see more research on cycling head protection, and to see our helmets perform well in the initial Virginia Tech tests. It is important to remember that every impact is a unique event. No rating system can prove if a specific helmet will or will not prevent, or even reduce the risk of concussion. This is why we encourage riders to choose a helmet that offers the most coverage that they're willing to wear, that is designed to the most relevant standards for the riding they do, and to inspect and replace their helmet regularly." 

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