Bike Serial Numbers
Serial Numbers [aka Frame Number or VIN] have become a set feature on modern bikes. The format of the number is manufacturer specific ... a "secret" most manufacturers seldom share. Serial Numbers are, in most cases, stamped or pasted on the frame. [See the graphic for common SN areas on your bike ... the Bottom Bracket is most common]
Some manufacturers list two or more numbers on their frames usually in the same location, please check with your bike manufacturer [or your bike shop] which is the unique VIN [Vehicle Identity Number] for your bicycle.
More recently bikes are being sold with a metalized sticker featuring a barcode and serial number, this in addition to a machine stamped number. Composite [carbon] frames can't be "stamped", however, in addition to a bar code sticker on Bottom Bracket, manufacturers punch the SN into the inner housing of the Bottom Bracket or within the Head Tube ... best to check with your Dealer in such cases.
It is always good practice to make sure of the frame number as we are also sadly faced with unscrupulous Dealers who trade in fake, branded frames.
The ASTM [formerly known as the American Society for Testing and Materials] Subcommittee F08.10 established standard Vehicle Identity Numbers (VIN) for bicycles in the US. Same was released in late 2003. The main objective being to facilitate recalls and identification of stolen property. Most US bicycle manufacturers identify bicycles according to the Standard Specification for Bicycle Serial Numbers [ASTM Document F 2268]. This Specification calls for the following:
5.1 Form—The serial number shall possess the following form:
SN 1 2 3 4 5 6 7 8 9 10 11 where the eleven alphanumeric characters have the following allocations:
1,2,3—Unique make, manufacturer, and plant of manufacturer code. The three zero characters, 000, denote that this information is unspecified within the serial number, and are used where this unique code has not been previously established.
4,5—Year of manufacture, last two digits of western calendar year.
6—Month of manufacture, where:
A = January; B = February; C = March; D = April; E = May; F = June; G = July; H = August; J = September; K = October; L = November; M = December.
7,8,9,10,11—Unique five character unit production number, in a format defined by the manufacturer. The manufacturer shall apply five characters, no more and no less, to result in the a serial number length of 13 characters on one line, SN and eleven characters. Additional characters used by the manufacturer shall not be on the same line.
6.1 Location—The serial number shall be placed, without obscurement, on the outside of the bicycle frame within 15 cm (6 in.) of the axis of rotation of the cranks by means of either engraving, decal, or stamping...