If you are having trouble finding your serial number, there are a few places to check depending on your model.
For Most Bikes
Flip the bike over and look between the cranks on the bottom of the frame. Older bikes may have it stamped underneath. We do have both zeros 0 and Os in our serial numbers, so please try your best to distinguish between the two.
LTE
There is a small QR code sticker on the back of the drive unit when you remove the rear wheel. The best way to access this is to remove the back wheel and scan the QR code with your phone.
MTE
The best way to get the serial number is to download the TQ app and pair your bike with it. After you pair your bike, look under bike info in the TQ app. You can find the QR code on the bike by removing the drive unit guard; it's on the inside of the frame.