Japanese Patent # S54-57737 - Sun-Bow

Japanese Patent S54-57737 main image

This patent appears to be for the p-pivot spring adjustment system on a Sun-Bow derailleur. It is one of three patents regarding features of this derailleur.

In the various patent databases, this patent is marked with a letter 'A', which may indicate that, unlike the other two patents, this is a full patent.

I cannot read Japanese, but I am assured that scan 1 also mentions the company name 'Yamashita Iron Works Ltd', and the address 'No 36 Sambocho 4-Cho, Sakai, Osaka'. This is the name and address given on the SY advert on page 254 of the 1956 Japan's Bicycle Guide.

So the SY brand and the Sun-Bow brand appear to originate from the same company.

Browse associated derailleurs.

Sun-Bow derailleur thumbnail
Sun-Bow (2nd style) thumbnail
Sun-Bow (3rd style) thumbnail