Also here is some history of the Super Plate.
Moveable Jockey Pulley
The Huret Duopar provided the archetype for the moveable jockey pulley. In 1976, Huret invented and patented a rear derailleur with the jockey pulley mounted on a separate unsprung parallelogram. The jockey pulley on this derailleur floats freely up and down 1.5 inches, which is the difference in radius between a 14-tooth and 34-tooth sprocket. The jockey pulley is just the right distance from the sprockets in every gear, so the Duopar shifts a bit early in every gear. SunTour and Shimano responded with their own moveable jockey pulley rear derailleurs, the MounTech and the Super Plate. They had to install a spring in the second parallelogram to get around Huret's patent. Moveable jockey pulley derailleurs have extra pivots and extra parts so they're inherently less rugged than conventional rear derailleurs. Mountain bikers want strong equipment, so the MounTech and the Super Plate were dropped. The Duopar is the only survivor of the genre.
From Complete Guide to Upgrading Your Bike. By Frank J. Berto.
Last edited by truthseeker14; 11-26-20 at 09:46 PM.