Since the start of manufacturing the Brompton bicycle, all frames have been stamped with a frame number; in 2001 a serial number was also introduced.
The first bikes were stamped, roughly, in batches of 500 or so. It seems often not all of the batch was used up or there were multiple batches in play causing some inaccuracies. Therefore the chart below is probably best seen as a guide; I suggest using other factors such as the Sturmey Archer hub date for example to assist in dating the bike.
Frame numbers are stamped into the bottom bracket shell section, on the flat behind the seat tube.
The introduction of the serial number makes things a lot easier to date an individual bike; the first two digits represent the year of manufacture while the 3rd and 4th digits represent the month of manufacture. For instance, the bike with serial number 1903220161 was manufactured in March 2019.
Serial number stickers are to be found on the back of the seat tube, notably moved from the top to the bottom of the tube in 2013 and swapped to a laser etched metal plate later on in 2015.
The first bikes were stamped, roughly, in batches of 500 or so. It seems often not all of the batch was used up or there were multiple batches in play causing some inaccuracies. Therefore the chart below is probably best seen as a guide; I suggest using other factors such as the Sturmey Archer hub date for example to assist in dating the bike.
Frame numbers are stamped into the bottom bracket shell section, on the flat behind the seat tube.
The introduction of the serial number makes things a lot easier to date an individual bike; the first two digits represent the year of manufacture while the 3rd and 4th digits represent the month of manufacture. For instance, the bike with serial number 1903220161 was manufactured in March 2019.
Serial number stickers are to be found on the back of the seat tube, notably moved from the top to the bottom of the tube in 2013 and swapped to a laser etched metal plate later on in 2015.
