# Where is the frame number on a Factor bike?

Canonical: https://www.cyclesite.co.uk/trust/frame-numbers/factor
Last reviewed: 2026-08-05

**Quick answer:** The frame number on a Factor is usually underneath the bottom bracket, etched or printed on a label because the frame is carbon. Photograph it as soon as you own the bike: high-value road frames are heavily targeted.

On a Factor, check underneath the bottom bracket first, then the rear dropouts and head tube. Factor builds high-end carbon road frames, so the number is etched or printed rather than stamped. These are expensive bikes and a common theft target, which makes recording the number early worth the two minutes it takes.

## Start under the bottom bracket.

This is the most common place to find a Factor frame number. It is the part of the frame between the pedals, on the underside.

1. Put the bike somewhere safe and well lit.
2. Turn it upside down carefully, or place it in a workstand.
3. Look underneath the frame where the cranks meet the bike.
4. Wipe away mud, grease or road dirt.
5. Use a phone torch if the number is hard to read.
6. Take a clear photo before typing the number into a checker.

### If it is not under the bottom bracket

- Near the rear dropouts, where the back wheel fits into the frame.
- Around the seat tube.
- On the underside of the down tube.
- Near the head tube at the front of the bike.
- On the original sales receipt.
- In your Factor registration email or paperwork.
- With the Factor dealer that sold the bike.

## What a Factor frame number looks like

A unique alphanumeric code, etched or on a bonded label under the bottom bracket. Factor does not publish a public serial format, so use the complete code.

### Not the frame number

- Factor Ostro
- Factor O2
- Factor LS
- Factor Hanzo
- Black Inc wheels
- Frame size
- Fork serial number
- Component code

## Buying a used Factor

A clean-looking bike is not always a safe buy. Before you pay, ask the seller for a clear photo of the frame number and check it against stolen-bike records. You should also ask for:

- The original receipt or proof of purchase.
- The seller’s name matching the receipt where possible.
- Clear photos of the bike from both sides.
- A photo of the frame number.
- Any service history.
- Details of upgrades or replacement parts.

## Bottom line

The quickest place to find a Factor frame number is underneath the bike, near the pedals. Look for a stamped code or barcode sticker, copy the full number, then check it before you buy, sell or register the bike. A used Factor can be a brilliant buy, but the frame number is the detail that protects you.

## Frequently asked questions

### Is a Factor frame number the same as a serial number?

Yes. Most people use frame number and serial number to mean the same thing. It is the unique identifying code attached to the bike frame.

### Do all Factor bikes have a frame number?

Most Factor bikes have a frame number or serial number. Check the locations described above first; on older frames the marking can be shallow or worn, so clean the area and check in good light before concluding it is missing.

### What if the Factor frame number has been removed?

Do not buy the bike. A removed or damaged frame number is a major red flag. It may make the bike harder to register, insure, resell or prove as yours.

### Can I check if a Factor bike is stolen by the frame number?

Yes. Use the frame number to run a stolen-bike check before buying. You should also ask the seller for proof of ownership and check that the details match the bike.

### How do I register a Factor bike in the UK?

Find the frame number using the locations described above, then record it against your Factor. It is free, and you need an account so we know where to send the alert. If that exact number is ever reported stolen to us, we email you. If anyone then lists a bike carrying it, the listing is hidden until the seller proves it is theirs.

## Related pages

- Free stolen-bike check: https://www.cyclesite.co.uk/stolen-bikes
- What a used Factor is worth: https://www.cyclesite.co.uk/value/factor
- Stolen Factor bikes: how to check one before you buy: https://www.cyclesite.co.uk/stolen-bikes/guide/stolen-bikes-by-brand-factor
- Used Factor prices by model: https://www.cyclesite.co.uk/value/factor
- Frame numbers for other brands: https://www.cyclesite.co.uk/trust/frame-numbers

Source: Cyclesite editorial, reviewed 2026-08-05. HTML version: https://www.cyclesite.co.uk/trust/frame-numbers/factor