Continuing with the concept of vertical shortening/lengthening through defining the route, let’s look at how this applies to pant legs.
First we define the journey. Pants start at the waist and end at the hem. For leg length, the route is thigh to ankle.
The goal is to change the leg length but keep the same leg opening aka hem circumference.
Here I have two lovely examples from vintage tapered leg pants patterns drafted for individuals with different heights.
The first one S4886 is described as pant with slim tapered leg and shaped hem in proportioned sizes for short 5’3” and under, medium 5’4” to 5’6” and tall 5’7” and over. The leg length alterations occur at a single shorten/lengthen alteration line on the pattern tissue printed approximately halfway down the leg.
The second one, S3257 is described as pencil pant with slim tapered leg and side slit hem in proportioned sizes for short 5’3” and under, medium 5’4” to 5’6” and tall 5’7” and over. In this case, leg length alterations occur right at the hem, moving the hem circumference along the vertical axis accordingly.
In both cases, all the vertical length is added or removed at a single location.
Note that the location where the pattern is adjusted is in the lower portion of the leg. This is because generally there is less shaping in the lower leg, easier pattern alteration1, and also because some pants patterns may be drafted with inseams of different lengths between the back and the front.
The location of the knee is not needed for fitting either, typically trousers are tapered from the hip to the ankle in a smooth line. The knee is just a landmark the route passes by as it travels between thigh and ankle. Like when the pilot makes an announcement over the intercom “we will soon be passing the knee, look out the window on the right for the best view!”
As long as we have sufficient circumference for knee to move (readily determined in fitting), there is no need to assess knee location for any style of pant.
And even if the knee location is part of the design feature, again there is no need to assess, this can be readily altered during fitting if one fits with the TDCO approach.
I leave you with a photo of Rihanna where you can clearly see the "fashion" knee is not aligned with the anatomical position of the knee. Fashion is all about illusion, there are no rules.
Position of notch on inseam
Love reading all about this. This substance is like a window into your thought process. Such a privilege to get to learn from you.