Abstract: A drawing wheel is intended for exerting tension on a grooved ring while optical fibers are being laid in helical grooves in the core, in order to stretch the ring in a cabling line. The invention is aimed at defining a radius for the wheel in terms of the dimensional characteristics of the ring so that the fibers are kept longer than the grooves as the ring leaves the cabling line and reverts to an initial tension-free state. The radius of the wheel is such thatR'>(p.sup.2 /(4.pi..sup.2 r))-(r+h)where p and h respectively denotes pitch and depth of the helical grooves, and r denotes radius of a central portion of the core circumscribed by bottoms of the grooves. The wheel radius is preferably on the order of one meter or more.