If you own an MK1 Chopper, an early MK2 Chopper or a Chopper Sprint,
you’re stuck with the rear hub date as identification, All
sprints were produced 1972 1973.
These early models had the frame number consisting of seven numbers...
although some late early models have only six!
I have found no way of dating these models... although they usually
fall within a production run of only a couple of years depending
on model.... And most U.K. issue bikes would have had a Sturmey
3 speed rear hub to date.
All MK1 and most MK2 up to late 1972 have their frame numbers stamped
on the left rear dropout.
This is the bit of flat steel that the rear wheel bolts into, on
the other side to the chain. To read it fully you often have to
remove the rear wheel nut and washer, and of course clean off the
dirt or rust.
This is the
same bike as the hub on the previous page
1972 and on bikes had their frame numbers moved up to the seat tube,
under where the seat clamps onto the frame, running up the tube
from bottom to top.
The later frame numbers consist of two letters, followed by five
six or seven numbers. This is where it gets easy...
The FIRST letter (usually "N")
indicates the factory the frame was made at... obviously most U.K.
bikes originated from Nottingham... hence most of our bikes start
The SECOND letter indicates the month
the frame was built... this letter should relate to the rear hub
date within a couple of months either way, depending on stock levels
at the factory.
Here’s the list;
January A, February B, March D, April E, May G, June H, July K,
August L, September M, October N, November P, December S.
The THIRD in the sequence is a number,
this indicates the year of production, 4 is 1974, 5 is 1975 etc
And 1981 is 1, 1982 is 2. (It starts with a '4' because this type
of numbering only started in 1974)
The rest of the numbers in the frame number are the bikes serial
Therefore, a bike with frame number ND46057 Would have been produced
at Nottingham (N) in March (D) in 1974 (4) and be frame number 6,057
produced that month.