Every factory-built bike will have a serial number, usually to identify the model and date of production. The serial number can be in different places depending on the manufacturer.
Most typically, the serial number is printed or engraved on the underside of the bottom bracket shell, where the cranks and frame meet. Other common places include the outer/inner face of the non-drive side chainstay (the frame tube closest to the chain), or under the head badge.
If you’re still having trouble locating your bike’s serial number, reference the manufacturer's website for helpful tips.
Take a lot of pictures.
Not just for the 'gram. Pictures of you with the bike will prove ownership.
Pictures of the bicycle’s drive-side (the side where the chain is) will allow experts to identify unique components.
Plan on taking these pictures:
- Serial number (see pic 1),
- You and the Bike together,
- Drive-side picture of the bike (to display components),
- Overhead handlebar shot,
- Any unique or non-stock additions: how does your bike stand out?
Formerly NationalBikeRegistry.com, Project529.com is a free online database which will store the serial numbers for all of your bikes. They offer lifetime registration with only a name and email address.
After creating an account, input all the previous data into these web forms.
Congratulations! Your serial number and important information are saved!
Now if your bike is stolen, you have a far better chance of recovering it.
Seek out your local law enforcement's website and do a quick search for bicycle registration. Many larger police departments (and even some smaller ones) will have a form to register the serial number and other important information about the bike.