When Castelli engineered the first aero jersey for road racing back in 2006, everyone thought they 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 their aerodynamic consultants expected limited gains, so they named the jersey Split Second, though, like now, they thought even small gains were worth pursuing. In the end the gains were pretty substantial, and they completely revolutionized the look of the pro peloton. Castelli are now on the sixth major revision of their aero jersey. Each generation has become more aero and better fitting. The Aero Race 6.0 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 they’ve worked to make the jersey comfortable for their long hours of training and then racing in every possible weather condition. It’s their most aero and most comfortable Aero Race Jersey yet.