The Fox Maple calc of lift should not be considered as general advice. The weight and configuration of the timber needs to go into a center of gravity calc then the lift needs to be evaluated as a lever. The load varies as the frame tilts upwards and at the angle as force is applied. The ideal angle of pikes should be parallel to the tangent of the arc of rotation, this is important for the initial application of pikes, force increases, in both directions, as pikes deviate from parallel.