What does “bb” stand for in my Diamondback BMX bike's serial. How can you use a Redline BMX serial number to determine the. It literally can be a randomized number that's ensured/verified to be unique. And in some cases the serial number has nothing to do with the model year. Sometimes the year is embedded in the serial number, but the algorithm for determining that is based upon the maker and the model.there is no universal serial number to model year conversion. For example, if the tractor was made by Sears then you probably could narrow down the year based upon the years of production of that particular model at Sears. Even then it may not be possible, but without that information there is not enough criteria to figure it out. The serial number alone is not enough to determine the year unless you also include the maker and the model number.