Vintage Bike Dating Pt1: Shimano Date Codes

Dating a classic bike can be very tricky. Your first port of call should always be the frame serial number, but that's not always an option as many frames don't have frame numbers stamped on them, and if they do they are often impossible to decipher. There are many examples of frame-builders using frame numbers that do make sense, but chances are if you're reading this then you are not that fortunate. There are other ways to try and narrow it down (retro catalogue scans, frame detail, decals & tubing stickers etc.) but again they can be quite vague and inconclusive.

HH date code on a Shimano rear derailleur means it was manufactured in August 1983

If you're lucky enough to have Shimano parts on your classic bicycle, it's actually very easy to get pretty close. This alone, however, is not concrete evidence that your bike is from a certain year, but it's an excellent starting place. Using components to date a vintage bike is a good way to put you in the right era. After that you can use other factors such as frame details & colour scheme to narrow it down even further, we'll cover frame details in another post, so for now you can use this table below to help you get started.

The best parts to look for date codes of the Shimano parts are the crank arms, rear derailleur & hub bodies. These almost always have codes etched in, but unfortunately they don't always have them. If you have a full Shimano groupset you should be able to find a two letter date code on at least one of the parts.

Front mechs do not always have a date stamp, but this lucky Shimano 105 does

The code system was in place from 1976 to 2003 and usually consists of two letters, the first relating to the year & the second to the month of manufacturer.

 YEAR MONTH
A = 1976 A = JANUARY
B = 1977 B = FEBRUARY
C = 1978 C = MARCH
D = 1979 D = APRIL
E = 1980 E = MAY
F = 1981 F = JUNE
G = 1982 G = JULY
H = 1983 H = AUGUST
I = 1984 I = SEPTEMBER
J = 1985 J = OCTOBER
K = 1986 K = NOVEMBER
L = 1987 L = DECEMBER
M = 1988
N = 1989
O = 1990
P = 1991
Q = 1992
R = 1993
S = 1994
T = 1995
U = 1996
V = 1997
W = 1998
X = 1999
Y = 2000
Z = 2001
A = 2002
B = 2003


Please note, it is very common for older bikes to use components from a year or two (sometimes) more prior to the actual build year, so always use this as a rough guide. There are also instances of date codes being way out, so it's always a good to cross reference the codes with the years of production for that particular model of the component.




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