Ski boot

A ski boot comprising at least two portions having overlapping edges for surrounding the skier's foot or ankle, and at least one fastening and tension device for interconnecting said portions, said device comprising a cogged strap attached to one of said boot portions and adapted to cooperate with means for hooking and tensioning said one portion or the other portion, wherein said cogged strap comprises cycloidal teeth consisting of elongated cycloidal segments generated in the plane of said strap by points disposed at spaced angular intervals along a circumference externally of the rolling circumference, said fastening and tension means comprising a rotary disc provided with studs disposed at spaced angular intervals along a circumference concentric to the axis of rotation of said disc and of a diameter greater than the strap width, said circumference and said studs corresponding to said external circumference for generating said cycloidal teeth on said strap, whereby said disc is inclined with respect to said strap in the direction toward the strap end, and means for guiding said cogged strap under said disc and keeping said strap in meshing engagement with the disc studs, so that when said studs are driven for rotation they engage said teeth only on the disc half nearest to the strap.