Originally Posted by
T-Mar
The following represents the current understanding of the various serial number formats used on Centurion models marketed by Western States Imports in the USA. Serial numbers were statistically analysed and the results compared against component date codes and extant literature.
1980-1990 Japanese models:
Most Japanese models during this period use a serial number format WXYZZZZ where;
W = a letter, purpose uncertain, but probably indicates manufacturer or Centurion
X = a number, indicating the calendar year of manufacture
Y = a letter, indicating the fortnight of manufacture (A = wk 1 & 2, B = wk 3 & 4, etc)
ZZZZ = four digit number, probably indicating frame number during fortnight
Example: N4E0283 indicates the 283 frame manufactured during the period of weeks 9-10, for the year 1984.
The letter prefix for these codes is typically 'N'. It has been suggested that this represents National, the Japanese market brand for Panasonic, which are built my Matsu****a. While the Panasonic branded models use a similar format, there is no prefix letter, nor is there a letter prefix on the Matsu****a manufactured Schwinns. This suggests the N-codes are be another manufacturer. reportedly Tano, though this is unconfirmed.
However, a number of circa 1984-1985 Centurion have turned up that match the Matsu****a format.
Miki manufactured models (circa 1975-1980)
During the late 1970s, Japan based Miki appears to have manufactured the upper end Centurion models for Western States Imports;
Serial number format Myfxxxxx, where,
M = Miki
y = number indicating year of manufacture
f = letter indicating fortnight of manufacture (i.e A = weel 1-2, B = weeks 3-4,,,,Z = weeks 51-52)
xxxxx = sequential frame number within the fortnight
Example: M7C11265 is the 11,265th frame manufactured by Miki during the 3rd fortnight of 1977.
. . .
This quote:
Last edited by T-Mar; 05-03-17 at 04:51 PM.
The Centurion serial numbers with the fornmat Nytxxxx,
where N = "N" frame manufacturer designation of a Japanese frame manufacturer.
y = digit, last digit in the year
t = alpha character for the manufacture time frame within the year.
It has been often stated that "t", time frame, alpha character indicates fortnight within the year.
This "fortnight" time frame never seemed right to me, as this is for a Japanese manufacturer.
For this manufacturer, where did this fortnight idea come from? I have seen no documentation to corroborate the time frame as fortnight.
This serial number format for Centurion is found from 1978 to 1989, 12 years. I have done a year by year analysis of the third character, the time frame character, for this serial number format.
The analysis shows that of the 26 letters of the alphabet, only 15 letters have been reported in serial numbers.
If the time frame is fortnight, i think you can expect that more than 15 letters would be used.
Of these 15 letters, three letters where only reported once in the 12 year history.
If you exclude these, then there are twelve letters.
All the other 12 letters were reported at least 15 time each, over the 12 years of serial numbers.
Twelve letters for twelve months?
Here is how the letters would decode as months:
A = January
B = February
D = March
E = April
G = May
H = June
K = July
L = August
M = September
N = October
P = November
S = December
This letter/month decoding is exactly the same as TI Raleigh serial numbers from 1973 to 1989.
The three letters with one reported occurance: "C", "F", "O".
This analysis is for 275 serial numbers over the 12 years, an average of almost 2 serial numbers per month.
Over the 12 years "P" is the most common letter found, November. November seems like a good time to manufacture frames to be in place for the start of the next year bicycle season.
The analysis does not include "N" serial numbers from Centurian Australia, Diamondback mountain bikes, or any of several other brand names that had frames with serial numbers with the same format. However serial numbers that I have seen from these sources have no exceptions to the month time frame letters that I have listed above.
* * * *
A similar analysis of Miki serial numbers will reveal that the third character of the serial number for time of year of manufacture is unlikly to be fortnight.
More likely to be monthly, but using a different subset of letters for month than listed above.
A = January
B = February
C = March
D = April
E = May
F = June
G = July
H = August
J = September
K = October
L = November
M = December