THE FIRST AERO JERSEY PROJECT WAS CALLED SPLIT SECOND. When Castelli engineered the first aero jersey for road racing back in 2006, everyone thought we were crazy. Back then, aero was only for TTs. Performance clothing meant moisture management. And you could win the Tour de France with a baggy jersey that was little more than a polyester T-shirt. Even our aerodynamic consultants expected limited gains, so we named the jersey Split Second, though, like now, we thought even small gains were worth pursuing. In the end the gains were pretty substantial, and we completely revolutionized the look of the pro peloton. Each generation has become more aero and better fitting. The Aero Race W Jersey benefits heavily from CFD analysis of wake flow in the riding position for fabric and seam placement. It also benefits from pro riders' feedback, as we've worked to make the jersey comfortable for their long hours of training and then racing in every possible weather condition. It's our most aero and most comfortable Aero Race Jersey yet. But we're already working on an update.