A parameter known as the knitting capacity of fibers is critical to process control and optimization. An experiment compared measurements of fiber properties that changed during knitting with their measurements prior to knitting. Different loads during knitting affected fiber and yarn geometry and properties. Pneumatic spinning manufactured two ply cotton yarns with 25 tex for tricot knitting. Physical and mechanical properties decreased during knitting. Major changes occurred due to overloads and extreme values of sinking loop depth, causing fiber jamming. Experimental data yielded fiber knitting capacity partial coefficients for yarn properties accounting for optimal knitting zones. 2 refs.