Significance
Helmets are designed to protect your head and brain from permanent injury resulting from an accident or crash on your bike. According to the NHTSA, 70 percent of individuals involved in fatal bike crashes suffered from a head injury, so protecting the head is quite important. Those who don't wear helmets are 14 times more likely to suffer a fatal crash than those wearing helmets.
Safety Standards
Since 1999, all bicycle helmets sold in the United States must meet safety standards established by the Consumer Product Safety Commission. Helmets will often have a CPSC sticker inside, demonstrating that the helmet meets the standards for coverage, stability, strength, visibility and impact protection.
Types of Helmets
Helmets come in a variety of types. Many, including road, mountain and sport, are largely distinguished by such minor characteristics as shape, weight and venting. Specialized helmets, such as downhill mountain bike helmets and BMX helmets, have further differences, including extra coverage and additional protection that meets such stricter standards as the ASTM F1952 downhill mountain bike helmet standard or the ASTM F2032 BMX standard.
Helmet Fit
When purchasing a helmet, fit is an important attribute. Helmets will not fit every head properly and you should try the helmet on before buying it. The helmet should be snug, with little movement, and should sit level on the head an inch above the eyebrows.
Helmet Laws
There are state or local helmet laws in 36 states and the District of Columbia. State law governing helmet use exist in 21 of those states. Many helmet laws pertain only to minors or children under a certain age, but some extend to every cyclist, emphasizing the importance of wearing a helmet.