A rolling contact bearing (1) providing a radially inner ring (2) into which a shaft of a pinion unit can engage, a radially outer ring (3) which can be inserted into a cylindrical seat (4) provided in a frame (5), a plurality of rolling bodies (6) arranged between the two rings (2, 3) so as to allow the radially inner ring (2) to rotate with respect to the radially outer ring (3), and an axial locking element (10) which is mounted on a lateral annular recess obtained in the radially outer ring (3) and can be screwed to the frame (5) so as to axially lock the radially outer ring (3) within the cylindrical seat (4); an axial retaining element (37), is associated with the radially outer ring (3) and radially interferes with the locking element (10) so as to secure the locking element (10) within the annular recess (11).