The problems involved in extending the well-established geometries of plain and lxl rib weft Knitted wool fabrics to include the half-carbigan and full-cardigan structures are discussed. The terms "Tightness Factor" and "relaxaiton valu" are introduced. It is shown that the simple fabric geometric formulas can be applied to Rib-based tuck structures of mean tightness factor, and that the relaxation value of any fabric depends upon the tightness factor and the relaxation temperature and conditions. Comparisons are drawn between the geometrical properties of plain-knit, lxl rib, half-cardigan and full-cardigan fabrics knitted from the same batch of worsted yarn.