A mobile platform such as, but not limited to, a skateboard type of structure capable of movably transporting an individual over a supporting surface. A wheel assembly connected to the platform includes at least one but more practically a plurality of wheels having a spherical configuration extending outwardly from opposite surfaces of the platform into engagement with the supporting surface so as to define at least two operative positions of the platform. A mounting assembly and each of a plurality of different embodiments of a bearing assembly are structured to facilitate a substantially universal, rotational movement of said wheel(s) relative to said platform. The different embodiments of the bearing assembly facilitate either a free or unrestricted universal rotational movement of the one wheel relative to the platform or alternatively a universal, rotational movement thereof concurrently about more defined rotational axes.