Novel molding compositions are described which are capable of being molded to form structural shapes, such as roller bearing cages, for example, and which comprise from about 40 to about 60% thermoplastic resin, preferably a polyamide, as a matrix, and uniformly dispersed therein, from about 5 to 15% and preferably about 5 to 10% carbon fiber, and about 15 to 25%, preferably about 15 to 20% glass fiber; the molded and set compositions having improved heat resistance, coefficient of heat expansion, bending strength, tensile strength, wear factor, coefficient of friction, heat conductivity, ease of processability and elastic deformability, as compared to similar compositions of the prior art.