Frame identification by frame number

Possible identification of bicycle frames using only frame numbers – initial guidance

Sometimes bicycles or frames are found with no makers’ transfers or badges on them –and occasionally with badges/transfers that are not correct!  In these cases examination of the frame number – where it is, what it is, and how it is, may be of some assistance at least in allowing other specialists to hazard a guess at the true origin of the frame or machine.  This note was begun before the V-CC published the two volumes of Lightweight Catalogues wherein the various marque enthusiasts (ME’s) had set out frame number lore for their makes.  These publications have been invaluable in adding accuracy to the information – but even including their data there are still well over 200 makes of possible lightweights to be confused over!  The author would be grateful to know of any inaccuracies and to receive further information to make the tables more comprehensive.

Examine the bicycle for the location of the frame number. See Table 1
Frame
It could be under the bottom bracket (BB) (Left), on the near side (N/S) (left when sitting on the bike) rear drop out, or on the seat tube cluster (saddle pin lug where it usually on the N/S but just sometimes on the back or O/S). Don’t be fooled by casting numbers, especially on the BB.  For example, some BSA frames have BSA and a 3 or 4 figure number cast into the base of the BB, this is just the casting number or perhaps a model number – it is not the frame number.  Nervex, the lug maker, also had their name on their BB lugs with a long design serial number.  Make a note of where on the BB the number is and its orientation – for example, is it upright or inverted for reading when lifting the front wheel up with the rear wheel still on the ground? Is it central or on the left or right flange of the BB as seen from this upright view? Most builders stamped the number at 6 o’clock when viewed from the N/S axle position but some set them at 9 o’clock (on the down tube side of the BB).  Some builders stamped the numbers parallel to the edge of the BB, yet others are random when compared over the years.

Other locations?
Most builders also stamped the frame number on the steerer tube of the front forks – but you may not wish to strip the machine down for this and in any case the forks may have been changed over the years. It can be worthy of note however that as sometimes very thick layers of paint can make the main frame number difficult to read –the steerer tube number is the only reliable evidence! Granby before 1940 used to punch the number on the underside of the head tube –along the bottom edge of the fork crown.  Dursley Pedersen numbers are underneath the leading edge of the front fork spreader plate which carries the lower steering swivel of this frame, with the frame’s size number on the right (near side of the same member).

2    Examine the frame number –what does it contain?   See Table 2
Is it a plain serial number or does it have some preceding numbers or letters (a prefix) or perhaps has some numbers or letters that follow the main number (a suffix)?  In order to be a prefix or suffix in this instance there should be a space between the number and the pre or suffix part, ot perhaps they are on a different line. Note that some number sequences contain a code –perhaps  made up by having the year of manufacture as the initial or last numbers or indeed both!  For simplicity this analysis stops at this point and refers you to the published sources or if you are a member of the Veteran-CycleClub (V-CC) to the appropriate ME.

3    Examine the type of character  – its font or its shape.  See Table 3
Note the type of font of the numbers or letters –are they curly or straight in style, and then their size –are they large or small – for this table a simple division into large or small has been made at 4mm (= 5/32 inch)

When you have established these frame number characteristics refer to the tables below and see if you can find a possible manufacturer.  Not all possible variations are shown in the tables to avoid them becoming too cluttered! Also very few makers maintained the same system of numbering throughout their production run – there will be many exceptions! However, if within the imperfections of this information you feel you have identified a maker, then if a member send your frame number details to the appropriate V-CC Marque Enthusiast together with any other descriptions such as the lugs and other integral maker’s features shown by the frame. Depending on the marque the ME may be able to date the machine very accurately from the number.

Table 1 Typical frame number locations for British bicycles

In this first version of the table if the location on the BB has not been recorded then a central upright position and orientation at 6 o’clock has been assumed.

Table 2  Construction of frame number  ® Indicates that a code usually a dating code is built into the number – see References or appropriate ME for further information

Table 3  Type of font of characters

References 

Lightweight Cycle Catalogues
Volume 1 and Volume 2 JPMPF.  Available from V-CC Publication Officer.

Volume 1:    Bates; Carlton; Claud Butler; Ephgrave; Gillott; Hetchins; Hobbs of Barbicon; Holdsworth; Raleigh; Rensch and Paris; Rotrax; Stallard

Volume 2:  Baines; Carpenter; Granby; Harrison; Higgins; Maclean; Mercian; Paragon; Mal Rees; Saxon; Stephens;     Viking

Hill Special: www.hill-special.co.uk , or ME if a V-CC member.

BSA:  Lightweight News No 13 Jan 2008 Available P Underwood c/o www.classiclightweights.co.uk

Dursley Pedersen: Dursley Pedersen Study Booklets.  Available from ME if a V-CC member.