Most consumers purchase bicycle helmets on the assumption that they are a regulated product that is will protect you in a bicycle crash. For decades, this is how millions of helmets have been marketed and sold. Sadly, thousands of concussions still result from bicycle accidents each year. Helmet companies and research scientists have teamed up to help solve the problem of the concussion epidemic in bicycling and other sports in an effort to cut down horrific head injuries that can have negative lifelong effects.
There are two different kinds of head injuries that are sustained during a bicycle crash. Those are skull fractures and brain injuries (often referred to as Traumatic Brain Injuries or TBI’s.) Typically, those two different types of head injuries are caused by two different mechanisms that occur when there is serious impact between your head and another object or surface. Those two mechanisms are:
Linear acceleration describes the impact of the skull when it hits the pavement. Helmets can be really effective in lessening the impact caused by linear acceleration and tend to do a great job of preventing serious injury or death by lessening the blow to the skull.
Rotational acceleration causes the brain to rotate causing shear strain. Although I’m no scientist, the strain from the brain rotating inside the skull causes damage to axons, which transmit information through neurons. You can read more about the detailed science on this by clicking the link below. Though there are other factors, rotational acceleration is the largest factor that determines how severe a concussion is. Helmets do NOT do much, if anything, to lesson rotational acceleration or the damage it causes to the brain.
Most helmet safety regulations and testing revolves solely around linear acceleration even though research shows that rotational acceleration should be front and center in the battle against concussions. There has never been a required or voluntary standards test for rotational acceleration. Scientists have warned that helmets are not adequately protecting the brain, and the focus needs to be shifted to develop helmets based on rotational acceleration.
Researchers have been measuring rotational acceleration for many years, and the equipment exists to test it, but major manufactures have not agreed on a test because they haven’t developed a helmet that lessens rotational acceleration. If a helmet to protect against this doesn’t exist yet, then there is really no use testing it.
Though helmets are not everything they should be, or even what most of us believe they are, wearing a helmet can help minimize your injuries in some types of bicycle accidents. So, even though they aren’t perfect, my advice is to wear one! I do 😉