Tern bikes have two important identifiers: the Service Tag Number and the Frame Number. They are not the same thing. The Service Tag Number starts with a capital T and sits under a QR sticker. The Frame Number is engraved into the bike frame and is the number most commonly used for insurance, police reports and third-party ownership records.
That number matters. It helps you register the bike, check if it has been reported stolen, prove ownership, value it and sell it with more buyer confidence. Here is where to find it, how to read it, and how to check it before you buy.
Check a Tern frame number
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On a Tern bike, the Frame Number is a 10 to 13-character alphanumeric code engraved into the frame. Tern says it is either at the bottom of the seat tube or on the bottom bracket, depending on model. The Service Tag Number is different. It is an 8-character code starting with T under a QR sticker.
Find the engraved Frame Number.
Tern engraves the Frame Number directly into the frame: at the bottom of the seat tube on models like the GSD, HSD and Vektron, or on the bottom bracket on models like the BYB and Link.
- Check the bottom of the seat tube, the upright tube the seat post slides into.
- If it is not there, check the bottom bracket area between the pedals.
- Clean away dirt and use a torch. Engraving can be shallow.
- Look for a 10 to 13-character alphanumeric code.
- Take a clear photo once you find it.
Make sure you copy the full number. A single missing or misread character can give the wrong result.
What does a Tern frame number look like?
The Tern Frame Number is 10 to 13 characters and engraved directly onto the bike frame. The Tern Service Tag Number is 8 characters, starts with a capital T, and sits under the QR code sticker. Useful, but it is not the same as the frame number.
Do not use the model name, tyre size, barcode on a shop label, or any number printed on a component. The frame number belongs to the bike frame itself. For example, these are not usually the frame number:
- Tern GSD
- Tern HSD
- Tern NBD
- Tern Vektron
- Tern Quick Haul
- Tern Orox
- Tern BYB
- Tern Link
- Tern Verge
- Tern Node
- Tern Eclipse
- Tern Joe
- Bosch motor number
- Battery serial number
- QR code alone
- Service Tag alone
- Accessory serial number
- Rack serial number
The number you want is the unique frame code that belongs to the frame itself.
Frame Number or Service Tag: what is the difference?
Tern uses both, and they are not the same number. The Frame Number is engraved into the frame and is the reliable ID for third-party registration, insurance and theft recovery. The Service Tag Number helps with Tern Care, warranty and accessories.
Where to find the Tern Service Tag Number
The Service Tag is usually easier to spot than the engraved Frame Number.
- Look for the QR sticker near the down tube or bottom bracket.
- The Service Tag is the 8-character alphanumeric code under that sticker.
- It starts with a capital T.
What does a Tern Service Tag look like?
An 8-character alphanumeric sequence starting with T, shown under the QR sticker. Record it alongside the Frame Number, but use the engraved Frame Number for ownership and stolen-bike checks.
Two numbers, two jobs
The Service Tag and Frame Number confusion is real on Tern bikes. The Service Tag helps with Tern Care, warranty and accessories, while the engraved Frame Number is the reliable ID for third-party registration, insurance and theft recovery.
The detail that protects you.
A frame number is one of the most useful details on a used bike. It connects a Tern to its owner, its registration record and any stolen-bike reports.
You may need it to:
- Check if a Tern bike has been reported stolen.
- Register your bike.
- Sell your bike with confidence.
- Get an accurate bike valuation.
- Make an insurance claim.
- Report a stolen bike to the police.
- Prove the bike is yours.
If you own a Tern, take a photo of the frame number and keep it with your receipt. If the bike is ever stolen, that detail can make a real difference.
Buying a used Tern? Check the frame number first.
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.
Red flag. Be careful if the seller refuses to show the frame number, says they cannot find it, gives only a partial code, or pressures you to pay quickly. A genuine seller should understand why you are checking.
Check a Tern frame number on Cyclesite
Found the number? Run a free stolen-bike check before you buy. Enter the Tern frame number into the checker and look for any matching reports. It only takes a moment, and it can help you avoid buying a bike with a bad history. If the bike looks clear, you can also value it and compare similar Tern bikes for sale.
What to do if your Tern has been stolen.
Report it as soon as possible. You will usually need the frame number, photos, make, model, colour, size, location and any unique marks or upgrades.
- Report the theft to the police.
- Get a crime reference number.
- Add the bike to stolen-bike databases.
- Update any existing bike registration record.
- Contact your insurer if you have cover.
- Watch used bike listings for matching bikes.
- Keep photos, receipts and messages in one place.
Include anything distinctive, such as upgraded wheels, unusual tyres, scratches, stickers, lights, mudguards, racks or replacement parts. The more detail you provide, the easier it is to identify the bike if it appears for sale.
Tern frame number FAQs
Where is the frame number on a Tern GSD?
Tern says the Frame Number is at the bottom of the seat tube on GSD models.
Where is the frame number on a Tern HSD?
Tern says the Frame Number is at the bottom of the seat tube on HSD models.
Where is the frame number on a Tern Vektron?
Tern lists the Vektron with the Frame Number at the bottom of the seat tube.
Where is the frame number on a Tern BYB?
Tern says BYB models have the Frame Number on the bottom bracket.
Where is the frame number on a Tern Link?
Tern says Link models have the Frame Number on the bottom bracket.
Is the Tern Service Tag the same as the Frame Number?
No. Tern says the Service Tag is an 8-character code starting with T. The Frame Number is 10 to 13 characters and engraved into the frame.
What if the Tern Frame Number has been removed?
Do not buy the bike. A removed or damaged Frame Number is a major warning sign and can make the bike hard to register, insure, resell or prove as yours.
Can I check if a Tern is stolen by frame number?
Yes. Use the engraved Frame Number to run a stolen-bike check before buying. Ask for proof of ownership and check the details match the bike.
Looking for another brand? See the full bike frame number guide.
Bottom line
On a Tern, the Frame Number is engraved at the bottom of the seat tube (GSD, HSD, Vektron) or on the bottom bracket (BYB, Link), depending on model. Copy the full engraved code, record the Service Tag too, then check it before you buy, sell or register the bike. A used Tern can be a brilliant buy, but the Frame Number is the detail that protects you.
Frame numbers by brand
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Editorial standards
Last reviewed by the Cyclesite editorial team. Published by Cyclesite, Companies House No. 13238473.