Abstract: A pair of roller wheel assemblies that are secured in longitudinally spaced relationship to an elongate platform of a skateboard. Each assembly includes a first centrally disposed resilient roller wheel and a pair of indepndently rotatable second rollers of generally frusto-conical shape situated on opposite sides of the first roller wheel. When the skateboard is guided in a straight path by a user the major portion of his weight is supported by the first roller wheels, and there is a minimum tendency for the skateboard to slow down in coasting. However, when the platform is tilted transversely by a user to guide the skateboard in a curved path, one of the second rollers is forced into rotatable frictional contact with the supporting surface to prevent the skateboard slipping relative to the latter.