Shimano had launched their Positron indexed system in 1975, and it soon became clear that indexing was not going to go away - so SunTour had to respond. The SunTour Mighty Click (wacky name!) was their first response. Unlike Shimano’s low-end effort, the Mighty Click was a mid-range design, with a slant parallelogram and an aluminium rear knuckle.
It’s not entirely obvious from looking at it but my understanding of the Mighty Click is that all the indexing is in the lever (like Shimano’s later SIS and unlike the 1979 SunTour SMS Max). The derailleur has a sprung outer cable stop (in a cylinder inside the parallelogram) called ‘Wire Saver’ which is equivalent to Shimano’s ‘Light Action’ sprung cable clamp. I think the Mighty Click used a conventional Bowden cable.
This example has a Japanese-style hanger plate, with the slot pointing towards the rear.
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