A method for fabricating a belt with upstream treatment of a tension member. The belt comprises a belt body made of a polymeric material having elastic properties, having a top ply as belt backing and a substructure having a force transmission zone, and a tension member embedded into the belt body. The tension member has been treated with crosslinked polymer; in an upstream stage of the belt fabrication method, voids in the tension member are filled at least partly with crosslinked polymer and the tension member is sealed with an envelope layer of crosslinked polymer, this being done, in a single treatment stage or in at least two treatment stages, by wetting of the tension member with an overall treatment mixture comprising at least one prepolymer, at least one crosslinker and at least one solvent or dispersion medium, and then drying of the treated tension member.