A coupling system of a sealing assembly with a rotating annular member, in particular a ring of a rolling bearing, wherein the sealing assembly is a low friction sealing assembly, in particular designed for a hub bearing unit for a vehicle, insertable in an annular gap delimited by a rotating member and a stationary member, which are mutually coaxial, to protect at least one crown of rolling bodies arranged between the stationary member and the rotating member, and comprising: a first annular shield provided with a first sleeve portion integral in use with the rotating member and a first flange portion which extends radially and overhangingly from the first sleeve portion; a second annular shield provided with a second sleeve portion integral in use with the stationary member and with a flange portion overhangingly carried by the second sleeve portion, radially on side of the support member opposite to the first flange portion and in front of it; and an annular sealing ring provided with at least one first and one second annular lip; wherein the first sleeve portion of the first shield is delimited by a lateral mounting surface facing towards the rotating member and having conic-truncated geometry with tapering directed so that a greater diameter φc of the lateral mounting surface is arranged on the side of the first flange portion and essentially at a first end of the first sleeve portion from which the first flange portion overhangingly extends; and wherein the sleeve portion couples with an assembly seat of the rotating annular member formed by an annular shallow recess delimited: by a conic-truncated bottom surface having tapering directed in the same sense as the tapering of the lateral mounting surface and by an axial shoulder arranged on the side opposite to the flange portion; and wherein the conic-truncated bottom surface of the annular shallow recess has a length in axial direction essentially identical to the extension in length in axial direction of the first sleeve portion and the axial shoulder is defined by an annular relief which delimits the shallow recess towards a frontal free rim of the rotating annular member; characterized in that, in combination: i)- the annular relief of the rotating annular member has a rounded saw-tooth profile in radial section defined towards the shallow recess by a conical surface with a tapering facing the conic-truncated shaped surface and which joins the conic-truncated shaped surface, so that the total axial length of the annular shallow recess is greater than that of the first sleeve portion in the direction of extension in axial direction and ii)- the annular shallow recess defining the assembly seat of the rotating annular member is obtained on a lateral cylindrical mounting surface of the rotating annular member starting from the side opposite to the frontal free rim of the annular rotating member, the diameter of the lateral cylindrical mounting surface of the rotating member is essentially either equal to or slightly greater than the diameter φb of the annular relief at a maximum radial height thereof; and iii)- the annular shallow recess defining the assembly seat of the rotating annular member is obtained so as to become deeper towards the annular relief, at which the annular shallow recess has a maximum radial depth d1; and the greater diameter φC of the conic-truncated lateral mounting surface, towards the rotating annular member, of the first sleeve portion being such as to make an interference coupling, either forced or slightly forced, between the first sleeve portion and the annular relief already at a first end of the first sleeve portion from which the first flange portion radially and overhangingly extends. i)- the annular relief of the rotating annular member has a rounded saw-tooth profile in radial section defined towards the shallow recess by a conical surface with a tapering facing the conic-truncated shaped surface and which joins the conic-truncated shaped surface, so that the total axial length of the annular shallow recess is greater than that of the first sleeve portion in the direction of extension in axial direction and ii)- the annular shallow recess defining the assembly seat of the rotating annular member is obtained on a lateral cylindrical mounting surface of the rotating annular member starting from the side opposite to the frontal free rim of the annular rotating member, the diameter of the lateral cylindrical mounting surface of the rotating member is essentially either equal to or slightly greater than the diameter φb of the annular relief at a maximum radial height thereof; and iii)- the annular shallow recess defining the assembly seat of the rotating annular member is obtained so as to become deeper towards the annular relief, at which the annular shallow recess has a maximum radial depth d1; and the greater diameter φC of the conic-truncated lateral mounting surface, towards the rotating annular member, of the first sleeve portion being such as to make an interference coupling, either forced or slightly forced, between the first sleeve portion and the annular relief already at a first end of the first sleeve portion from which the first flange portion radially and overhangingly extends.