Mercury Wheels M9C Carbon Road Wheelset. The Mercury Wheels M9C Carbon Road Wheelset has been designed with one thing in mind raw speed. With an abundance of depth at 80mm, this wheel has graced many bikes in the pro peloton. Not only is the carbon fiber rim deep and fast, but the shape has been optimized to create one of the most aerodynamic profiles available. During windy rides and races it is often difficult to keep from getting blown from one side of the road to another due to the depth of the rim. Mercury Wheels, however, designed the rim with a rounded trailing edge which allows the cross winds to navigate with the least amount of disturbance. The M series rims are the lightest Mercury Wheels creates thanks to a slightly different carbon layup process than their S series. The M series rims are laced with Sapim's CX Ray spokes, their most popular bladed model, which are incredibly strong as well as lightweight courtesy of their proprietary butting. The M9C wheels also utilize Mercury Pro hubs, which engage with 3 pawls for a nearly immediate responsiveness that takes advantage of the rims' low rotational inertia. The front hub has an extra wide 72 millimeter flange for reduced flex under hard efforts and confident stability at speed. Both hubs have a 15 millimeter axle that tapers to accommodate a traditional quick release and two and four over sized bearings in the front and back, respectively. Additionally, the M9C's rims are a solid 23.5mm wide, which means you can run lower PSI for a more comfortable ride that corners with unparalleled confidence. Wider rims also have some counter intuitive effects when compared to those standard 19mm rims: they actually decrease rolling resistance and increase aerodynamics.