Cross country riding whether racing on a proper race course or rolling through wilder lands requires components that enable the rider to feel fast and light on the bike in all situations crossmax sl pro is the first mountain bike wheel to use the mavic patented ism 4d technology the rim is strategically machined to reduce weight and inertia removing material where its not needed and keeping it where it is to offer a more dynamic ride because not all race courses and trails are equal ism