Drag is the biggest retarding force acting on a bike and rider ... In certain cases, such as the Specialized S-Works Turbo Cotton and the Challenge Criterium RS, a 28c was not available and ...
As a full bike, the OSTRO is 7.23kg complete with pedals, bottles and cages in the Dura-Ace spec (no power meter). That's just 50 grams more than the S-Works Tarmac SL8, which weighs 7.18kg.