A tensioning roller/winder device comprising at least one roller bearing including inner and outer rings and at least one row of rolling elements between the two rings; a pulley surmounting the outer ring; and a retaining screw comprising a body and head. An abutment is provided on the body external periphery. First and second abutments are provided on the inner ring bore. The axial length between the head and the abutment equals the axial length between an inner ring radial side edge and the inner ring bore first abutment is greater than the axial length between a inner ring radial side edge opposite the screw head and the inner ring bore second abutment. The screw abutment contacts the inner ring first abutment during the body insertion into the inner ring bore in the desired direction, but contacts the inner ring second abutment during the body insertion in the undesired direction.