Rider bar assembly for a product support beam of a reheat furnace of the type suitable for reheating steel product such as slabs, blooms, bar stock and semi-finished products. The assembly has a rider bar which defines an upper contact surface on which a product to be heated is receivable, a base component which has an upper region with which a lower region of the rider bar is contiguous and support means by which the base component and the rider bar thereon are mountable on a product support beam of the furnace in which the product is to be reheated. The rider bar is formed of a high temperature resistant, solid ceramic material which is a low porosity and which has sufficient compressive strength for supporting part of the load of the product when the letter is received thereon and also on the rider bar of other assemblies mounted on the same and other beams. The base component is formed of a solid ceramic material which also has high temperature resistance and a compressive strength sufficient for supporting that part of the product load. The ceramic material of which the base component is formed has a low thermal conductivity whereby conduction of heat energy from the product, to the beam on which the assembly is mounted, is reduced.