In a rolling cart assembly, a smooth bumper assembly is provided that minimizes the likelihood of trapping dirt, grime, or the like. Corner bumper members having a smooth, uncrimped outer surface are provided with integral stiffening members and internally secured nuts so that the corner bumper members may be secured to a support frame by fasteners that extend in an outwardly direction from the inside surface of the support frame. Since the nuts are completely enclosed by the corner bumper members, the outside surface thereof are smooth and unbroken. Stiffening members may be co-molded or otherwise suitably formed integrally with and interiorly of the corner bumper members. Longitudinally extending side and end bumper strips are formed with an opening therein in order to receive V-shaped stiffening members. The side and end bumper strips are also secured to the support frame by fasteners that extend in an outward direction from the inside surface of the support frame so that the outside surface of the side and end bumper strips are also smooth and unbroken.