Bell's New Convertible Helmet

Until now, bikers have had to choose between ventilation and aerodynamics. But along with Giro's Synthe, Bell's new Star Pro aims to nullify that decision. With a slider that opens and closes all the vents with just a touch, the helmet goes from a well-ventilated cooling machine to a sleek aero wind-cutter, which—as I write this—just notched stage five of the Tour de France.

On your daily commute it's not always important that you beat your record over the bridge by a few seconds. But there's an unintended benefit for helmets like these on the road—bad weather.

If it's raining or cold, flip the vent shut and keep your head dry and warm. If it's a hot day, open up the vents so you're not taking a shower in your own sweat.

Oh, you wish more bike helmets came with built-in visors? This one does, held on by magnets.

Ethan Wolff-Mann is an editor at Supercomrpressor. He commutes through the rain. Follow him on Twitter @ewolffmann.