After starting the aero jersey revolution in pro cycling castelli have continued to perfect this piece while the 2015 aero race 50 jersey represented the biggest leap forward in terms of race performance the new castelli aero race 51 short sleeve jersey 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 but its not just aero its extremely light coming in at just 103g