An ice crampon including a metal armature, the metal armature being composed of a horizontal support plate, at least one front spike in the form of a blade, and an adjustment device for adjusting the length of said front spike between a withdrawn position and an advanced position. In the intermediate part, each front spike comprises two circular apertures for passage of a fixing screw in both the withdrawn and advanced positions, and in the rear part comprises a sliding link operating in conjunction with a positioning cross-member securely attached to the armature when adjustment is performed. The sliding travel corresponds to the longitudinal distance between the two apertures, and the positioning cross-member is notched over its whole width with a succession of rectangular notches and indentations further enabling transverse positioning of the front spike.