Bike serial numbers (2024)

All bikesall have unique serial numbers.¹

Finding a bicycle serial number

Most bicycles have their serial number engraved beneath their bottom bracket, but sometimes serial numbers are found in other places. Here are some examples of where and what to look for:

The bottom bracket (where serial numbers are typically located) is circled.
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A serial number on the underside of a bottom bracket.
Another serial number beneath the bottom bracket, aligned parallel to the frame.
Rad Power bikes have their serial number on the head tube. This is on the front of the bike.
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Some Schwinn bicycles also have the unique identifying number (their serial number) on the head tube.
A serial number located on a rear dropout. Some BMX bikes and a few Schwinn bicycles place the serial on the rear dropout. On older Schwinns there are numbers stamped on both the drive side and non-drive side rear dropouts; the one on the non-drive side dropout is the serial number.
Some bikes have multiple serial numbers.²When adding a bike to the Index, it's best to enter all the groups of numbers and letters separated by spaces.

Hopefully you can find the serial number on the bicycle you're looking at - email contact@bikeindex.org if you're having trouble.

Searching serials on Bike Index

Finding bicycles by serial number on Bike Index is a critical part of our functionality. When searching for a serial number, use our serial search bar - it's the second bar on our search form.

We've done a few things to make it more likely that you'll find the bike you're looking for.

Certain numbers and letters are difficult or impossible to distinguish between (e.g. 0 and O, S and 5). We treat all these numbers the same way - a search for 005LLL will match a bike with the serial OOS111.
We split bike serials up by spaces and store each separately. If you see multiple numbers on a bicycle - such as in the photo of the Look bike above - try searching for just one of the numbers at a time. Searching for either M4106I9CA1 or 200910427-2A will find the bike.
We do close serial matching - bikes with serial numbers that are close to the serial you entered are shown below the matching results under the heading "Serial Numbers Close to..." - given a search of a serial number with a couple numbers/letters that are different or missing.
We do not currently do partial serial searches. If you search for 1234, you will only find bikes with serial numbers of 1234 and serials close to that - not a bike with serial number of 12345689.

Okay, fine, so maybe there are a few bikes without serial numbers, but this is rare and typical only on hand made bikes or really old bicycles.↩
In this picture 200910427-2A is a manufacturer number and not a serial number. We recommend not including the manufacturer number when registering. If it looks like you've included a manufacturer number, we'll let you know!↩