The invention relates to a heel-piece for binding a boot on a gliding board that includes a frame including a vertical extension; a body rotatably mounted about the extension; at least two rods supported by the body, extending on respective sides of the vertical extension, the two rods each having a free end to cooperate with a housing in the heel of the boot; and a holding mechanism for maintaining a spacing between the free ends of the rods. The vertical extension supports at least one contact zone fixed in relation to the frame. Each rod cooperates with a respective portion of the contact zone, specific to each rod. The contact zone is arranged such that a rotation of the body about the extension, from a descent configuration, causes an increased spacing between the two rods. The invention also relates to a binding system and a gliding board equipped with such a binding.