SATURDAY, May 31, 2003 (HealthDayNews) -- Even the most experienced bike riders crash on average every 4,500 miles, according to the Bicycle Helmet Safety Institute.
Typically, that's when many cyclists first begin to think about wearing a helmet.
More accurately, that's when those who survive typically start thinking about the benefits of a helmet.
Head injuries are to blame for more than 75 percent of the approximately 800 deaths in the United States each year due to bicycle crashes. Research shows a bicycle helmet can prevent 85 percent of head injuries and many of these deaths.
A helmet works by reducing the peak energy of a sharp impact to the skull. To accomplish this reduction, a layer of rigid foam is required. Most bicycle helmets use expanded polystyrene (EPS), the white "picnic cooler" foam. Once crushed, EPS does not recover. Another foam, expanded polypropylene (EPP), does recover, but is much less common.
A stronger EPS called GECET appeared in 1992 and is widely used now. Another foam called EPU (expanded polyurethane) is used in Taiwan. It has a uniform cell structure and crushes without rebound, but is heavier and requires a manufacturing process that is not environmentally friendly.
In contrast, the spongy foam inside a helmet is for comfort and fit, but it does not provide any impact protection.
To do its job, a helmet must stay on the cyclist's head, even when the helmet is hit more than once -- usually by a car first, and then by the road. That's why a helmet requires a strong strap and an equally strong fastener. The helmet should sit level on the cyclist's head and cover as much of the skull as possible.
Above all, with the strap fastened, the cyclist should not be able to remove the helmet by any combination of pulling or twisting. If it comes off or slips enough to leave large areas of the head unprotected, adjust the strap again or try another helmet. Keep the strap comfortably snug when riding.
More information
Here's more on children and helmet safety from the American Academy of Pediatrics.
