Every bike has a unique serial number on the frame. To find it, flip the bike and locate where the pedals and crank arm attach to the frame. The numbers are engraved and are sometimes hard to see, so be sure you're in a well lit room or have a flashlight/cell phone handy.
The photo below illustrates where to look for it.
We keep a record of all serial numbers at Riide, so you can always ask us for it if your bike has been lost or stolen.