Yoke

What it is

Look at the back of a pair of jeans and there is a horizontal seam a hand's width below the waistband, dipping to a point at the centre. The piece above it is the yoke. It is cut as a separate piece and joined to the back legs along that seam.

Why it is there

A body is not a cylinder. The seat curves out and the waist curves in, and cloth cut in one flat piece will not follow both. A trouser without a yoke deals with that using darts — small stitched folds that take up cloth at the waist. A jean deals with it with the yoke seam instead: the angle of the seam, and the shape of the two edges that meet at it, put the curve into the cloth without a dart in sight.

That is why the yoke's angle differs from one jean pattern to another. A steeper V puts more shape into the seat; a flatter one gives a straighter, roomier back. It is a fit decision, made at the block and tested on a muslin — the Standard Issue Jean's two fittings are described under Why a prototype's fit changes.

How it is built here

The yoke seam on the Standard Issue Jean is sewn with a 1.5 cm allowance and topstitched, like the rises. A double yoke — two yoke seams, sometimes seen on Western-cut jeans — is not something any project here uses, so it is not on this shelf.

What it changes

Functionally, it is where a jean's fit through the seat lives; a change of a few millimetres at the yoke shows on the body. Visually, it is one of the defining lines of a jean, and its topstitching wears and fades with everything else on the back.