an idler roller assembly is comprised of a polymeric tubular body and an end cap fitted within a cavity of the tubular body at each end of the tubular body . an inner circumferential surface of the tubular body defining the cavity is configured with a plurality of recesses to define first , second and third cavity portions , with the third cavity portion being adjacent to each end of the tubular body . the first and third cavity portions have an inner diameter that is greater than an inner diameter of the cavity , and the second cavity portion has an inner diameter greater than the inner diameter of the first and third cavity portions . an end cap configured to house a bearing race to support each end of the tubular body on a shaft is configured with a first end , a second end and an outer cylindrical wall therebetween . the outer cylindrical wall is stepped to provide first , second and third outer cylindrical surface portions sized to fit closely within the first , second and third cavity portions of the tubular body . the outer cylindrical wall is radially tapered between the first and second outer cylindrical surface portions to facilitate insertion of the end cap within the cavity of the tubular body .