At just 1255g, Cosmic Ultimate UST Disc is the ultimate balance of lightweight, stiffness and aerodynamics: the pinnacle of tubeless carbon wheels. The wheels are the lightest in their class and built with carbon spokes. he carbon rims are 45mm deep. The rim width measures 19mm wide internally and 27mm wide externally. This is optimal for 700x25mm tubeless tyres at a maximum safe pressure of 87psi, according to Mavic. The widest road bike tyre Mavic recommends using is 700x32mm. Because the mid-section carbon rims are not drilled, they do not require rim tape to remain airtight, simplifying tubeless setup. Rim to Rim technology The carbon fibre spokes and high, thin carbon hub flanges confer an aerodynamic advantage and the wheels use Mavic second generation of rim-to-rim technology (R2R), which runs 10 spokes from one side of the rim to the other through the hub and the spokes are made with unidirectional carbon fibers, so they don?t stretch. This totals 20 contact points on each rim. Mavic says the R2R design increases stiffness and removes the need to fit the spokes mechanically to the rim. The Cosmic Ultimate 45 Disc?s R2R is four times stronger than the previous R2R design. Oversize bearings Stiff hub axles and oversized cartridge bearings ensure the Cosmic Ultimate 45 Disc?s longevity. The hubs come with thru-axles (12×100 front and 12×142 rear) and can be converted to quick release. However, they only work with Center Lock disc brake rotors. The Shimano/SRAM freehub can also be fitted with a Campagnolo specific freehub body. Eight hour build time Each wheel?s 71 carbon fibre pieces take 10 workers eight hours to hand build. The which are wheels are designed, engineered and patented by Mavic in Annecy, France, are also 100% handmade in France too, unlike most other wheels manufactured by Mavic and their competitors. They benefit from a lifetime warranty and from a generous crash replacement policy (upon on-line registration at Mavic.com/care).