This gear caused me distress and dismay when it appeared. SunTour seemed to have abandoned the best design in the world (the slant parallelogram) and copied the geometry of the much despised 1976 Huret Eco, which was, in turn, the bastard child of the 1963 Huret Svelto.
The design did have some interesting details. SunTour had adopted a ‘Light Action’ style sprung cable clamp (in imitation of one of Shimano’s better features). The top pulley was dramatically off-set from the lower pivot, in an attempt to get the Huret geometry to provide a decent change over a wide freewheel.
Despite these touches SunTour’s decision to adopt this geometry was like Ferrari deciding to copy a Lada.