Evolving the revolution after starting the aero jersey revolution in pro cycling castelli have continued to perfect this piece version 51 builds on the race leading aerodynamics while making the jersey more comfortable and durable updated fabrics on the front and back showed a 2 watt gain in the wind tunnel compared to the previous version it may not sound much but over the course of a long ride or race thats a significant energy saving but itrsquos not just aero the aero race 5