Just in time for the Tour de France, Specialized has unveiled the S-Works + McLaren TT Helmet. It’ll be worn by Omega-Pharma QuickStep riders, Levi Leipheimer, and TT World Champion Tony Martin.

After spending many hours in the wind tunnel for their first collaboration on the Venge road bike, this second collaboration claims have used twice as much time in testing. The result? The fastest aerodynamic helmet in the world, according to Specialized, and it promises to be just the beginning of future aero development. The collaboration with McLaren on this helmet let Big S take advantage of their aerodynamics knowledge learned through years of F1 racing, with the vehicle manufacturer providing better measurement and interpretation of the wind tunnel and CFD data.

It’ll be available in “extremely limited quantities” in early 2013. UPDATED: More tech info added below…

Air enters through vents just behind the ears and escapes through small “slits” and the large central exhaust port. We’re waiting on word from Specialized on the internal channeling or other features, along with pricing and weights. Their data suggests this design actually reduces drag further then if the intake vents were covered.

Dual density EPS foam inside let them keep the helmet pretty thin without affecting safety, which Specialized says gave them more leeway to shape it the way they wanted at the front.

Specialized says the McLaren TT helmet is not only more aero in a straight line, but also in cross winds and when the rider is looking down (tail up).

Mark Cote, Specialized’s Aero R&D and Triathlon product manager, told us “the helmet is worth about 0.5 secs/km over the best helmets in the TdF today.”