What Happens When Consumer Reports Tests Bike Helmets

CR tests helmets once a year, and a lot of interesting stuff happens between the time the helmets arrive in the lab and the moment updated ratings are published on our website. 

The helmets rest at room temperature (62° F to 81° F) for at least 4 hours before testing because both heat and cold can slightly affect their performance. Because we’re doing comparative testing, we want to make sure they all start off on equal footing.

After they’re well-rested, helmets that come in various sizes (as opposed to universal or one-size-fits-most types) get fitted with a properly sized metal headform (they come in sizes A, E, J, and M). The best fit for our testing is the smallest headform that fills the helmet without extra padding.

Random observation: Matthew just happens to have a size M head, and Jose has a size J head. The two attempt some serious head-modeling with their corresponding headforms, below.

Matthew drops a weight to tug at the helmet’s strap, simulating what could happen in an accident—like if your body skids across the road with velocity while the helmet grabs the pavement. If the straps loosen significantly, the helmet gets a lower score. If the buckle breaks or fully releases (as it does here), the helmet gets a big fat ‘F.’ Matthew repeats the test with a fresh helmet just to make sure the failure wasn’t a one-off (it wasn’t). 

For this and the following test, two samples of a helmet model must perform satisfactorily for it to pass. Likewise, two samples must fail for a model to fail. When that happens, CR alerts the Consumer Product Safety Commission and the manufacturer, and designates the helmet as a “Don’t Buy: Safety Risk” in our ratings. For these helmets, testing ends here. “If a helmet can’t stay on your head, it doesn’t matter what else it can do,” Matthew says.

To test how well a helmet can absorb the force of an impact, Jose attaches a helmeted headform to a uniaxial monorail impact machine that hoists it 6.5 feet before dropping it. The helmet free-falls at about 14 mph onto a steel anvil—just like an amusement park drop-tower ride . . . minus the brakes. (These distance and speed numbers are based on CPSC safety standards and approximate the sort of skull-slamming you could suffer if you fall off your bike.) 

Jose performs this test on the helmet’s front, rear, sides, and crown. As the helmet hits the anvil, a sensor detects the amount of g-force exerted on the head form. Anything in the  300 to 320 G range is considered a potential failure and triggers additional testing.

With some products we test (hello, smartphones!) a crack could mean disaster for the durability rating, but breakage during bike helmet testing isn’t necessarily a bad thing. In a crash, the helmet’s job is to absorb as much of the impact as possible to protect your noggin. Sometimes, that impact cracks the helmet and that’s okay. Better your helmet than your head.

Remember: Your helmet is designed to withstand one bump. That’s it. Even if it looks fine after a crash, trash it and buy a new one. “Damage can be hard to detect,” Jose says. “The insides of the helmet can compress and lose the ability to absorb any more energy.” Translation: Your head will take the hit. Hard.

To subjectively gauge how well the helmet ventilates for comfort (nobody likes a sweaty scalp), Jose simulates a ride by sitting in a chair in front of a wind tunnel blowing at 17 mph. The wind tunnel allows for repeatable conditions that riding a bike outdoors would not.

Matthew evaluates how easy or hard it is to open and fasten the chin strap buckle—and docks points for those that pinch, are stiff, or restrict finger access. He says the magnetic buckles (shown above) are generally the best but not very common.

He also adjusts the straps and occipital clamp, which sits at the rear base of the helmet and hugs your head for a tighter fit. Top scorers have flexible, soft straps that slide like butter, with easy-to-open locking tabs. Occipital clamps ideally adjust automatically or with an easy-to-turn dial.

If you’ve ever thought that helmets look like futuristic takeout soup containers (what, just me?) it’s because most of them are made of expanded polystyrene (EPS), a type of plastic foam similar to the one used to make restaurant takeout containers. EPS is light, durable, and partially puncture-resistant when covered by a plastic shell—a perfect combo to protect your head, if not your order of ramen to go.

To see how a helmet’s reflectors and/or LED lights could appear in a car’s headlights, testers darken the lab and use a flashlight to illuminate the helmet from 10 feet away. It’s not a test, but it’s noted for each model’s ratings page.

“If you crash and hit the ground on a corner of the helmet, that rotational force is going to twist your neck and can lead to concussion,” Matthew says. The multi­directional impact protection system (MIPS) shown here reacts to hits by shifting slightly to minimize that twisting motion. Seeing this convinced me that it’s time to upgrade my helmet. Most bike helmets that CR recommends have this (or similar) technology, but we don’t currently test this function.

Fun fact: Lab 122 is Consumer Reports’ tallest, at 27.5 feet. It’s the only one that can accommodate the 17-foot-high impact machine used to test bike helmets. The lab’s floor surface is also particularly well-suited for dancing, which we determined after some (very unofficial) testing at the end of the day.