The invention provides a trolley wheel assembly for a conveyor system, e.g., an overhead conveyor system. In certain embodiments, the wheel assembly includes at least one wheel face having a contour (optionally a funneling configuration and/or one or more surface features) configured to facilitate flow of a fluid toward an open bearing assembly of the wheel assembly. In some embodiments, the wheel assembly includes an inner race, outer race, and bearings having a particular hardness arrangement, optionally together with a polymer wheel having certain filler features. Methods for cleaning such a trolley wheel assembly are also provided.