Idler and bearing assembly and a method of manufacturing same

A method of manufacturing an idler and bearing assembly, the method including the steps of:

• a) preassembling a bearing unit having a radially outer ring and a radially inner ring
• b) locating at least one tubular spacer of rigid material axially aligned with the inner bearing ring and abutting against at least one of the radially extending, axially opposite sides of the inner bearing ring;
• c1) overmoulding an outer wheel body of plastic material onto the outer bearing ring so as to provide an outer cylindrical surface adapted for being engaged by a driving belt;
• c2) overmoulding a central tubular core of plastic material into radially inner cylindrical surfaces of both the inner bearing ring and the at least one tubular spacer, thereby forming a sleeve unit integral with the inner bearing ring, the sleeve unit including the at least one tubular spacer and the tubular core axially extending along said radially inner cylindrical surfaces.