# Where is the frame number on a Transition bike?

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

**Quick answer:** The frame number on a Transition is usually underneath the bottom bracket or on the underside of the down tube, away from the suspension linkage. Check both before deciding it is missing.

On a Transition, check underneath the bottom bracket first, then the underside of the down tube and the head tube. These are full-suspension mountain bikes, so the bottom bracket shell is surrounded by pivots and the number is often placed somewhere flatter and easier to read.

## Start under the bottom bracket.

This is the most common place to find a Transition 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 Transition registration email or paperwork.
- With the Transition dealer that sold the bike.

## What a Transition frame number looks like

A unique alphanumeric code stamped or etched into the frame. Transition does not publish a public serial format, so use the whole code as it appears.

### Not the frame number

- Transition Sentinel
- Transition Patrol
- Transition Spur
- Transition Smuggler
- Transition Repeater
- Frame size
- Shock serial number
- Fork serial number
- Pivot bearing codes

## Buying a used Transition

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 Transition 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 Transition can be a brilliant buy, but the frame number is the detail that protects you.

## Frequently asked questions

### Is a Transition 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 Transition bikes have a frame number?

Most Transition 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 Transition 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 Transition 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 Transition bike in the UK?

Find the frame number using the locations described above, then record it against your Transition. 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 Transition is worth: https://www.cyclesite.co.uk/value/transition
- Stolen Transition bikes: how to check one before you buy: https://www.cyclesite.co.uk/stolen-bikes/guide/stolen-bikes-by-brand-transition
- Used Transition prices by model: https://www.cyclesite.co.uk/value/transition
- 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/transition