It is very hard for non-Japanese speakers, like myself, to uncover the secrets of Japenase derailleurs from before 1970. But the annual 'Japan's Bicycle Guides' shine a brief glimmer of light on the subject. These thick tomes showcased Japan's bicycle and bicycle component industry, and were, mercifully, written in English.

This, pleasantly moth-eaten, 1956 edition includes a few rather furry pictures of derailleur-equipped bikes, a tiny section actually devoted to derailleurs (including one SunTour and one Shimano and nothing else) and a small selection of quite interesting adverts.

A couple of highlights are:

• The Shimano advert on page 268 depicts a Shimano derailleur that I have never seen anywhere else. It also boasts that Shimano have the capacity to manufacture 150,000 freewheels a month, but only 5,000 derailleur sets.
• There is an advert for SY brand freewheels on page 254. This is the only advert for this brand that I have ever seen. It gives the manufacturer's name as Yamashita Iron Works Ltd. and the address as Sakai in Osaka Prefecture

• Publisher: Japan's Bicycle Guide
• Country: Japan
• Date: 1956
• Derailleur brands: DNB, Maruishi, Sanko, Shimano, SunTour, SY, Sun-Bow
• Derailleurs: Sanko SR, Shimano 333, SunTour 8.8.8. Wide