More and more, we're seeing bicycle helmet manufacturers move away from expanded foam in favor of higher-tech materials that provide better head-protection. The big boys have now gotten in on the act, as Trek has announced its WaveCel line of helmets – they're said to be up to 48 times more effective than foam alone, when it comes to preventing concussions.
Developed by orthopedic surgeon Dr. Steve Madey and biomechanical engineer Dr. Michael Bottlang, the WaveCel system incorporates a liner made of a proprietary collapsible cellular polymer. Upon impact, as the rider's head presses into the liner, that material first flexes and then crumples, dispersing energy. It also slides to one side within the helmet, in the direction of impact.
The latter feature is particularly important, as it helps to prevent rotational injury.
Also known as intracerebral shearing, this occurs when the helmet hits a surface (such as the road) at an angle, which is often the case in accidents. When this happens, the helmet's rigid shell catches against the pavement and causes the helmet to very rapidly twist around. The rider's head twists with the helmet, quickly enough that the brain doesn't quite keep up, moving a few milliseconds after the skull it's contained in. The result is the shearing of nerves and blood vessels, resulting in disabilities or even death.
Because the WaveCel material slides relative to the rest of the helmet, however, it allows the helmet to be suddenly twisted, without yanking the head around with it. A Trek representative tells us that WaveCel helmets should be replaced after receiving an impact, as is the case with other helmets.
The company is now offering four models of the helmets, which are being marketed under its Bontrager brand name. Prices range from US$150 for a commuter model, up to $300 for road-riding and mountain-biking versions.
Source: Trek
UPDATE (Mar. 22/19): MIPS, a Swedish company that manufactures a helmet system which helps reduce the chances of rotational injury, has issued a statement in which it claims that its staff has "subjected the new WaveCel helmet technology to their battery of tests, with results far below WaveCel's substantial claims of injury prevention."