Aero road helmets at the Tour

http://velonews.competitor.com/2012/07/tour-de-france/keep-a-lid-on-it-the-ins-and-outs-of-whats-covering-tour-riders-noggins_227475

Giro claims that its Air Attack is 12 percent faster than its own heavily vented Aeon helmet and only 12 percent slower than its Selector time trial lid. And it does it while keeping a rider cool, at least as cool as a bare head.