A variable friction shoe includes a midsole and an outsole. The outsole includes at least a first high-friction surface and at least a first low-friction surface, wherein the first low-friction surface remains prominent if vertical ground reaction forces (GRFs) are low and wherein the high-friction surface is prominent in response to increasing GRFs.

A sole capable of being integrated in a boot or shoe and a method of assembling the same. The sole comprises an outsole, made of at least a first material, which defines an exterior lateral shape and an inner space for receiving a filling material and a housing for receiving a rigid mechanical device having protrusions that extend through corresponding openings of the sole. A wall surrounding the housing, made of the first material, has a minimum thickness of 20 mils. A portion of the wall is shared with a heel-section of the outsole. A seal plate is provided for, at least partly, covering the wall. the seal plate is for preventing the filling material from entering the housing. The filling material, once the sole is assembled, comprises a layer covering the seal plate and the sole conceals the mechanical device except for the protrusions.

A sole capable of being integrated in a boot or shoe and a method of assembling the same. The sole comprises an outsole, made of at least a first material, which defines an exterior lateral shape and an inner space for receiving a filling material and a housing for receiving a rigid mechanical device having protrusions that extend through corresponding openings of the sole. A wall surrounding the housing, made of the first material, has a minimum thickness of 20 mils. A portion of the wall is shared with a heel-section of the outsole. A seal plate is provided for, at least partly, covering the wall. the seal plate is for preventing the filling material from entering the housing. The filling material, once the sole is assembled, comprises a layer covering the seal plate and the sole conceals the mechanical device except for the protrusions.

An article of footwear includes a forefoot region, a midfoot region, and a heel region. The article of footwear includes an upper and a sole structure connected with the upper. The sole structure includes a plate, a midsole defining a midsole height that extends from a bottom side to a top side of the midsole, and an outsole. The midsole height is taken at a maximum thickness of the midsole between the bottom side and the top side of the midsole. The midsole defines a plurality of spike apertures that extend from the bottom side of the midsole to the top side of the midsole, and a plurality of spikes are coupled to the plate within the spike apertures of the midsole. The midsole is configured to deform more than 10% of the height, expressed as a percentage.

An article of footwear includes a forefoot region, a midfoot region, and a heel region. The article of footwear includes an upper and a sole structure connected with the upper. The sole structure includes a plate, a midsole defining a midsole height that extends from a bottom side to a top side of the midsole, and an outsole. The midsole height is taken at a maximum thickness of the midsole between the bottom side and the top side of the midsole. The midsole defines a plurality of spike apertures that extend from the bottom side of the midsole to the top side of the midsole, and a plurality of spikes are coupled to the plate within the spike apertures of the midsole. The midsole is configured to deform more than 10% of the height, expressed as a percentage.

An article of footwear may include a sole structure comprising an outer member and a plurality of ground engaging members, including a first ground engaging member. The ground engaging members extend substantially downward from the outer surface of a sole structure. Ground engaging members, or cleats, may be auxetic structures that can increase their dimensions in a direction that is orthogonal to the direction of applied force or tension. The ground engaging members may comprise a series of faces joined along hinge portions that allow ground engaging members to flatten and expand significantly. The first ground engaging member may have a substantially three-pointed star-shaped pyramidal structure. The outer member may have a more elastic material than the material comprising the faces of ground engaging member. The outer member may have an inner surface with apertures that correspond with the ground engaging members of the outer surface.

An article of footwear may include a sole structure comprising an outer member and a plurality of ground engaging members, including a first ground engaging member. The ground engaging members extend substantially downward from the outer surface of a sole structure. Ground engaging members, or cleats, may be auxetic structures that can increase their dimensions in a direction that is orthogonal to the direction of applied force or tension. The ground engaging members may comprise a series of faces joined along hinge portions that allow ground engaging members to flatten and expand significantly. The first ground engaging member may have a substantially three-pointed star-shaped pyramidal structure. The outer member may have a more elastic material than the material comprising the faces of ground engaging member. The outer member may have an inner surface with apertures that correspond with the ground engaging members of the outer surface.

Traction systems for skis producing traction on snow and ice covered surfaces; the skis selected from a group consisting a pair of Back Country skis each are mounted with an apparatus; having DC powered controls, tilt switch, pressurized carbon dioxide (CO.sub.2) gas powered pneumatic actuators operating gripping parts; controlled by a servo unit. And further consisting a pair of snowmobile skis each having an assembly of parts; driven by an hydraulic rotor that pivots the skis, adjusting their position when cornering, providing traction, according to a snowmobile steering system. And is powered and controlled by at least one of: hydraulic steering system, an electro-hydraulic steering system; an electric power steering system using an electric motor instead of hydraulic rotor.

Traction systems for skis producing traction on snow and ice covered surfaces; the skis selected from a group consisting a pair of Back Country skis each are mounted with an apparatus; having DC powered controls, tilt switch, pressurized carbon dioxide (CO.sub.2) gas powered pneumatic actuators operating gripping parts; controlled by a servo unit. And further consisting a pair of snowmobile skis each having an assembly of parts; driven by an hydraulic rotor that pivots the skis, adjusting their position when cornering, providing traction, according to a snowmobile steering system. And is powered and controlled by at least one of: hydraulic steering system, an electro-hydraulic steering system; an electric power steering system using an electric motor instead of hydraulic rotor.

A sole system for an article of footwear can include a sole member and a protruding member assembly. The sole member includes outwardly and inwardly facing surfaces, a plurality of spaced apart first apertures extending though the sole member, and a plurality of first protruding members extending outward from and fixed to a base surface of the outwardly facing surface. The protruding member assembly includes a plurality of second protruding members that are interconnected by connecting portions, where the connecting portions are received on the inwardly facing surface of the sole member, and where each second protruding member is vertically movable within a corresponding first aperture of the sole member.