This Spanish Utility Model describes an early version of the Zeus Alfa Junior. The parallelogram and knuckles are pure Huret Svelto. But the pulley cage is pivotted between the pulley wheels. The example of the Zeus Alfa Junior in this collection has a pulley cage with an offest pivot.

This document includes some of the worst technical drawings that I can remember seeing. A key feature of this derailleur design is that the pulley cage should move in a plane that is parallel to the plane of the dropout mounting plate. In some of the drawings these two planes are horribly out of parallel. I know space is curved, but this is ridiculous.

• Publisher: Oficina Española de Patentes y Marcas
• Inventor: José Luis Eibar SA
• Country: Spain
• Date: Priority date September 1966
• Derailleur brands: Zeus
• Derailleurs: Zeus Alfa Junior