A conveyor belt for carrying bulk material while supported on troughing rolls has nearly inextensible longitudinal reinforcements in the edges only of the belt, above the margins of the transverse reinforcements. The belt is made of rubber or other elastomer of uniform thickness except at the edges which are substantially thickened on the top surface only, to contain the longitudinal reinforcements. The transverse reinforcements are preferably a spaced pair of fabrics, inextensible in the direction transverse of the belt but extensible longitudinally.