A bulging structure within the shoe insole that supports the arch of the foot.
Support for the arch is the oldest unsolved argument in shoemaking. The medial arch is a suspension bridge of bone and tendon that flexes with every step, and a shoe must decide how much of that work to take on. Take too little and the foot fatigues; take too much and the foot is immobilised and weakens. The best shoemakers have always treated the question as one of shape rather than padding.
The Shank and the Waist
In a traditionally made shoe, most of the support is structural and invisible. A shank — a tapered strip of steel, wood or fibreglass — is set between the insole and the outsole beneath the waist of the shoe, holding the arch clear of the ground and stopping the sole collapsing under load. Above it sits the insole itself, and beneath that a filling, classically of cork, which warms and compresses under the wearer’s weight until it holds an impression of that particular foot and no other. This is why a good pair of shoes becomes more comfortable with age rather than less, and why the first fortnight is the price of the following decade.
Comfort as an Argument
For most of its history the luxury shoe treated comfort as an unfortunate concession. That has changed. Clients who once accepted a punishing break-in period now expect a shoe to perform on the first wearing, and the houses have responded with moulded footbeds, cushioned insoles and lasts drafted around a broader instep. The engineering has become a selling point rather than a secret.
It follows that anyone selling fine footwear needs to be able to explain what is happening inside the shoe. A client comparing two pairs at similar prices is rarely persuaded by the upper alone, and the difference is very often the shank.