Updated 22th March 2026

Diamond Back Serial Decoder

Use the tool below to decode the stamping on your bottom bracket or dropout.

How to read your serial:

Most WSI-era Diamond Backs followed various ranges of alphanumeric formats (e.g., 2A1234, etc):

First Digit: The year of manufacture (e.g., 2 = 1982).

Letter: The month of manufacture (A = Jan, B = Feb, etc.).

Sequence: The unique production number for that year/month.

If your serial number starts with "VM", you can also refer to our History & Lore section for the breakthrough research on Koizumi's Manufacturing origins. This page has not been updated for some time and there's more work required.

Otherwise, have a go with the tool below and if you get stuck (because I am still compiling the logic), drop me a message. 

(It's key you use the features option which is prompted for Koizumi serials)

NB - I continue to work on the logic but at the moment the following formats work

1.LLLNNN (Fabrications by Jere)

2. VMNNNNN (Velo Manufacturing - tbc)

3. NLNNNN (Koizumi Factory)

FNNNNNNN (Fairly Bike Co. in progress)

24" models are not catered for at present and were minimal in production numbers.