I have decided that this patent relates to the Shimano Combi 12 firstly because it shows a derailleur on which the cable runs over a wee roller close to the outer cable stop, and secondly because it shows a hub which has a fat barrel much like the 3.3.3. three speed hub. I am not entirely sure whether Shimano made a coaster brake version of their 3.3.3. hub gear - but it seems more than possible. The gear cluster shown has only three cogs - could there have been a Combi 9?

This is the earliest US patent related to a derailleur that I have found that is in the name of Keizo Shimano himself.

• Publisher: US Patent and Trademark Office
• Inventor: Keizo Shimano and Masashi Nagano, assigned to Shimano
• Country: USA
• Date: US application filed June 1967, Japanese application filed June 1966
• Derailleur brands: Shimano
• Derailleurs: Shimano Combi 12