A radical change in design did not occur until the mid-1970s introduction of the first modern snowboards. With no previous designs to set the mould, snowboard designers had to experiment to find the right layout. The 1975 Burton Backhill had a 17 mm sidecut, giving the board a very short turning radius. The Backhill was extremely low-tech in comparison to contemporary ski designs, consisting largely of a sheet of plywood. A contemporary ski's torsion box design greatly improved torsional stiffness and would allow even greater sidecut to be effective. But in spite of the snowboard demonstrating that modern skis could carry much wider sidecuts, and that such a sidecut resulted in excellent turn performance, little came of this development. The snowboard market was ignored by the major ski companies through the 1970s and 80s.