Dating Japanese track bike frames – serial numbers.

Below are a couple of photos of the underbellies of Japanese NJS track frames. The bottom bracket shell usually has some numbers roughly stamped in which give the builder (and us) a reference of what the frame is.

Builders have their own unique ways of numbering frames and usually keep records of all of the frames they ever built, so if you took an old frame to them they could probably look it up, and tell you when it was made and for who, the size, and piping used and so on…. but usually our customers and friends just want to know what year the frame was built in.

This also applies to road frames, of course.

It’s usually pretty easy to figure out…for example the Nagasawa frame below was built in 1985 as shown by the 85, where the 11 means November. The 4 on the left refers to the frame being the 4th frame completed in November of 1985.

Nagasawa uses a very simple and logical numbering system, which helps, but other builders like 3Rensho (pronounced sahn-ren-show) had some more confusing numbers and letters in the mix, which are a bit more ambiguous.

Sometimes you need to also consider the Japanese calendar and the ‘Showa’ era. The second photo below is a 1987 3Rensho. The 1987 build year is represented by a ’62’ because in Japan 1987 is known more commonly as Showa 62. Here is a list of Showa years which are commonly seen on Japanese road and track frame serial numbers.

Showa 35 = 1960
Showa 36 = 1961
Showa 37 = 1962
Showa 38 = 1963
Showa 39 = 1964
Showa 40 = 1965
Showa 41 = 1966
Showa 42 = 1967
Showa 43 = 1968
Showa 44 = 1969
Showa 45 = 1970
Showa 46 = 1971
Showa 47 = 1972
Showa 48 = 1973
Showa 49 = 1974
Showa 50 = 1975
Showa 51 = 1976
Showa 52 = 1977
Showa 53 = 1978
Showa 54 = 1979
Showa 55 = 1980
Showa 56 = 1981
Showa 57 = 1982
Showa 58 = 1983
Showa 59 = 1984
Showa 60 = 1985
Showa 61 = 1986
Showa 62 = 1987
Showa 63 = 1988
Showa 64 = 1989

Nagasawa_Vintage_track_frame_light_blue_Restored_083Rensho_njs_keirin_track_frame_Takizawa_blue_restored_08

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