The bearing unit comprises a plurality of bearing elements rotatable relative to each other. A shell encircles the plurality of bearing elements. A body of resiliently compressible material is located between the shell and the plurality of bearing elements and possesses a predetermined compressibility. This body of resiliently compressible material retains the plurality of bearing elements relative to the shell and permits free adjustment of the plurality of bearing elements relative to the shell within limits determined by the predetermined compressibility of the resiliently compressible material.