The r1rsquos carbon thermoplastic composite shell and carbon braided rail reduce weight and increase saddle stiffness antares r1 is for the chameleon medium spine if you have an intermediate degree of spinal flexibility approximately 90 degrees between your straight legs and your back when bending over as far as you can keeping your legs straight a shouldersrsquo width apart you are a chameleon your degree of spinal flexibility helps you so far before you need to rotate