An apparatus designed to protect the wearer against head injuries. Cyclists have worn cranial protection since the late 19th century, though the padded leather “hairnets” seen in vintage photos of Eddy Merckx did little to safeguard heads. The first commercially successful modern bike helmet was the Bell Biker, released in 1975. Constructed from hard foam, it was designed to dissipate the force of a single catastrophic impact by breaking (and, it seemed, to make cyclists look like spelunkers). That basic concept didn’t evolve much, even as aesthetics improved and features like ventilation, soft plastic covers, and superior aerodynamics were added. But recent advances in helmet technology are enhancing protection. MIPS is a dual-layer system that allows interior pads to slide relative to a hard shell on impact, reducing rotational forces. Last year, Smith Optics began making helmets that replaced foam with Koroyd, a polymer that compresses on impact, dispersing energy.
Skiing, whitewater paddling, and, to a lesser degree, climbing followed similar paths of helmet development and adoption. The deaths of Michael Kennedy and Sonny Bono, who skied into trees within a week of one another in 1997–98, caused a sudden mass embrace of helmets; today 73 percent of U.S. skiers and snowboarders wear them. Still, the number of head injuries suffered at mountain resorts has increased—there were 15,000 in 2010—and the severity of injuries has also been on the rise. Many analysts suspect that helmets provide a dangerous sense of invincibility that leads to riskier behavior. Meanwhile, better snowsports equipment enables inexperienced skiers and riders to reach higher speeds, terrain parks offer ever bigger features, and resorts unveil increasingly gnarly in-bounds slopes in response to surging demand.