Abstract: A shock absorber support rail is formed of an elongated, stiff, but springy, plastic extruded strip that is M-shaped in cross-section. The M-shape is turned on its side and its legs are substantially parallel. The converging legs of the V-shaped center portion of the M-shape form a central, acute angle apex where they join and they form upper and lower apices at their junctures with the parallel legs. The converging legs are bent to form integral leg parts that are angled at different acute angles relative to the axis of the M-shape, so that the spring rate may be varied during compression of the parallel towards each other. The strip has the same spring rates per unit length along the full length of the strip. Thus, pieces of predetermined length may be cut off the strip to form separate support rails, each of a predetermined spring strength dependent upon its particular length.

Abstract: An undamped spring having multi-spring rates is provided in the heel support portion of a shoe for resiliently compressing under heel pressure against the ground and returning a substantial portion of the energy of the pressure to the wearer's foot. The spring is formed of upper and lower leaf-like legs which are integrally joined together at an acute angle whose apex is directed forwardly relative to the shoe. An intermediate leaf-like leg is located between and integrally joined with one and extended towards the other of the upper and lower legs. Thus, heel pressure compresses the upper leg towards the lower leg until the intermediate leg is engaged and, thereafter, spring compression continues at an increased spring rate.

Abstract: A power drive system to augment pedalling of a bicycle including a reversible magnetically balanced electromagnetic field positioned in proximity to one wheel of the bicycle, at least one permanent magnet mounted on the wheel to pass through the electromagnetic field when the wheels are rotated by conventional pedalling, and a reversing switch responsive to the position of the permanent magnet to alternate the polarity of the electromagnetic field thereby alternately attracting the permanent magnet into the electromagnetic field and thereafter repelling the permanent magnet outwardly from the electromagnetic field. A reed type switch is positioned to respond to the movement of the permanent magnet to reverse the polarity of the electromagnetic field. A proximity switch is triggered by conventional pedalling to turn off the power when pedalling ceases. Thus, the power drive system assists in the pedalling but does not provide power when the cyclist is coasting.