Abstract: This clamp ring comprises a strip provided at one end with a series of transversally extending ridges or like profiles and carry at its other end a housing for a rotatably mounted screw which engages said ridges for tightening the ring. The housing has a straight bottom supporting the ridged part of the strip and said housing is disposed relative to the ring such that the first operative screwthread of the screw is disposed substantially on a diametral plane of the ring, while the screw extends tangentially to the circumference formed by the ring and substantially perpendicularly to said diametral plane. The ridges are produced by stamping or pressing and are in the form of a sector of a nut. The rack is displaced outwardly of the plane of the strip, which comprises two planar side portions flanking an offset central portion providing a guide groove in the lower face of the strip, which co-operates with a corresponding raised portion provided in the bottom of the housing.