Year after year we have refined our Ksyrium technology and expanded its features (ISM3D, asymmetrical rims, double butted spokes, front carbon hubs...). So Ksyrium is constantly getting lighter, stiffer and stronger. And this year we've done it again. For 2016 the Ksyrium SL becomes the Ksyrium Pro SL with a brand new rim, based on our new rim weight saving technology: ISM4D (Inter Spoke Milling 4 Dimensions). With ISM4D, each part of the rim is precisely machined leaving just the material needed to guarantee the stiffness and strength of the wheel. The result is a superlight rim at just 370g that also saves you 4 watts thanks to its smoother aerodynamic shape. The total wheel weight remains at an impressively low 1395g. Matching Yksion Pro tyres The rim is matched with our Yksion Pro tyres that offer a supple 127 TPI casing, Kevlar beads, a well-balanced rubber compound that offers the best blend of grip and rolling resistance and a weight of only 190g in 23mm and 205g in 25mm. Ksyrium Pro SL is available with 23mm or 25mm tyres.