A spring-type shank for a shoe sole is formed on the bottom of a shoe assembly during manufacture of the shoe. The heel end of the shank is formed so that it is raised slightly from the heel seat region of the insole to provide a "spring shank". The shank is formed directly on the bottom of the shoe insole from a strip of initially flexible, uncured thermosetting material which may be fiber reinforced. The spring portion at the heel end of the shank is formed by placing a wedge between the shoe insole and the heel end of the shank strip during the curing process thereby to cause the heel end of the shank strip to cure in a raised, inclined attitude, spaced from the bottom of the insole, while the more forward, remaining portions of the shank strip cure in secure attachment to the insole bottom.
A system for stiffening the shank of an insole uses a stiffener which is formed from an initially flexible and deformable strip of thermosetting resin, preferably mixed with reinforcing fibers such as fiberglass. A length of such shank strip material is applied onto the bottom of an insole and the insole, with the shank strip in place, is mounted in a special fixture. The fixture holds the strip on the bottom of the insole and also assures that the insole and shank strip will be held in the proper configuration, with the proper bend at the ball and the arch. With the shank strip and insole so held an external stimulus, such as radiant heat, is applied to the shank strip to activate and cure it in place on the insole bottom. The fixture may be adjusted to provide precisely repeatable control over the curvature of the insole either to assure that the insole conforms precisely to the bottom of a particular last or to modify the curve at the insole bottom and configuration of the shank to suit any particular requirement of the manufacturer.
Footwear, in particular sports footwear, which includes a vamp associated with a substantially flat foot-supporting lower part or sole unit. This latter includes at least one portion formed of woven composite material having a part positioned in correspondence with the metatarsal region of the user's foot and a part positioned corresponding with the arch region of the user's foot, wherein the part of the portion present in the metatarsal region is flexible and enables the sole unit to flex during the use of the footwear and wherein part of the portion present in the plantar arch region is rigid.