How to check a bike frame number?
Direct answer · Cyclesite
To check a bike frame number, first find it: it is a unique alphanumeric code, usually stamped under the bottom bracket where the pedal cranks meet, and sometimes on the head tube, seat tube or rear dropout. Note it down exactly, then run it against a UK stolen-bike database to confirm the bike is not reported stolen and to see its history. On Cyclesite every listing is checked against UK stolen-bike databases automatically before it goes live, so the frame number on any bike for sale here has already been verified. If you are buying privately rather than through a screened marketplace, run the check before you hand over any money, not after, because once a stolen bike is in your possession you can lose both the bike and the cash you paid for it.
Last reviewed: 2026-07-17
Where to find the frame number
The frame number, also called the serial number, is most often stamped into the metal under the bottom bracket shell, the part of the frame the pedal cranks pass through, so you usually have to turn the bike upside down to read it. If it is not there, check the head tube at the front, the seat tube, or the rear dropouts near the back wheel. It is a unique alphanumeric code, typically 6 to 12 characters, and is different from any model or size code printed on a sticker.
How to check the number
Once you have the exact number, search it on a UK national cycle database used by police forces. A clear result means the frame is not currently reported stolen; a match means you should not buy it. On Cyclesite you do not have to do this manually, our frame-number lookup runs the same check instantly, and every listing is screened against stolen-bike databases before it is published, so a flagged frame never reaches the marketplace.
Why the frame number matters when buying used
A frame number is the one part of a bike that cannot easily be changed, which is why it is the basis of every stolen-bike check and ownership record. Always confirm the number stamped on the frame matches the number in the listing or paperwork before you pay. A seller who cannot or will not show you the frame number is a red flag, on a private sale that is the moment to walk away.
Average used bike prices by category (UK)
| Category | Average price | Sample size |
|---|---|---|
| road | £1,477 | 13 |
| ebike | , | 6 |
| mtb | , | 3 |
| gravel | , | 2 |
| bmx | , | 1 |
Last updated: 2026-07-17
Related Questions
Is a frame number the same as a serial number?
Yes. On a bike the terms are used interchangeably, both refer to the unique alphanumeric code stamped into the frame, most commonly under the bottom bracket.
Can I check a bike frame number for free?
Yes. UK stolen-bike databases offer free frame-number checks, and Cyclesite checks every listed bike automatically at no cost to the buyer.
What if there is no frame number?
A missing or ground-off frame number is a serious warning sign on a used bike and often indicates a stolen frame. Do not buy a bike whose frame number has been removed or tampered with.
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