A vision of what might have been - this derailleur would have been a killer product in 1975 (when Europe had not yet fully succumbed to the charms of Japanese designs). Unfortunately it took Simplex another decade to wake up and make this gear - effectively an affordable Shimano Crane. By that time it was only of interest to industrial archaeologists.

• Derailleur brands: Simplex
• Categories: Simplex - the bitter end
• Country: France
• Date of introduction: 1985?
• Date of this example: unknown
• Model no.: 640
• Weight: 263g
• Maximum cog: 30 teeth?
• Total capacity: 30 teeth?
• Pulley centre to centre: 46mm
• Index compatibility: friction
• Chain width: 3/32”
• Logic: top normal
• B pivot: sprung
• P pivot: sprung
• Materials: aluminium knuckles and outer parallelogram plate, steel inner parallelogram plate and pulley cage plates.

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