It varies, but in most cases the first 2-3 digits are letters identifying the factory that made it. The next 2-4 digits are in the Rule Numbers indicating the date of manufacture. So 0312 would be December 2003. Any bike shop could help here too.
For Japanese Koizumi Diamond Back BMX frames, the year is the first number found on the serial number. Check out our Japanese/Koizumi guide for more information. On Diamond Back Taiwanese Fairly made BMX frames, the year is the second number in the serial number after the letter F.
The serial number is located on the underside of the frame where the pedals and crank arms are attached. Most likely you will have to turn your bike over. Look for a series of letters and numbers. The serial number is usually in the format U161K0123456 or DAY16A123456.
Each manufacturer has its own identification system. But the first digits usually indicate the year and then the month of manufacture. And the remaining numbers indicate the specific ID of that bike.
Today, most Diamondback bicycles are made by Kinesis Industries, a Taiwan-based company with a factory in China that specializes in frames and forks.
Most serial numbers are located under the bottom bracket where the two cranks meet. Turn your bike upside down and write down the number. If there is no serial number near the cranks, you should check other common places, including the front headset or rear stays.
@Jordan – If you check the bottom bracket, there may be a serial number or other information engraved into the metal. Post a picture and look for identifying numbers/letters on the frame and if any of the parts originally came with the bike list what they are if you can.
Sometimes abbreviated as a serial number, SN, S/N, or SNID, a serial number is a unique number used for identification and inventory purposes.
Most (but not all) bikes have a serial number. They are usually referred to as a bike serial number, but sometimes also as a “frame number”. They are stamped onto the frame of a bicycle and are six to ten digits long.