Is there a common system to assigning serial numbers to a bike?

I have a Schwinn in the shed and wouldn't mind knowing what year it is, will most manufacturers or bike shops be able to identify this for me?

Does the same rule apply to components, or is this going to be a manufacturer specific kind of thing?

Bicycle serial numbers are mfr. specific. Older vintage Schwinn numbers are fairly well documented so if you post pics of the bike, serial number, and if it is a '76 or later the 4-digit number on the headbadge we can tell you a lot.

You can find data on Schwinn and a few others, but for the most part many of us have just given up trying to place a vintage bike by its exact serial numbers. Allot of time we can get pretty close matching its design and components via the Velo base catalogs...

The folks in the Classic & Vintage forum can help you get info on the Schwinn.

I don't have the link handy right now, but there is a site where you can date old Schwinns to the exact date of manufacture. I have a Schwinn Twinn tandem that I was able to determine was built on Oct 22, 1964.

You can only do that with Schwinns built in '76 and later having a 4-digit number stamped on the headbadge. That number is in the form (dddY) where ddd represents the ordinal day and Y represents the last digit of the year. Schwinn first started recording the day of assembly in 1974 specifically for the purpose of being able to handle recalls, but for the first two years Schwinn only provided that information to its dealers.

The serial number date code site you mentioned is here. Note that the serial number recorded dates only indicate when the *frames* were made. The actual bikes were normally built weeks, months or in some cases even years later. Schwinn built frames in batches and more limited production frames (e.g. tandems, fillet-brazed models) tended to sit in inventory longer than high-volume frames before being painted and built into bikes.

With a frame built that late in '64 it is very likely your bike wasn't built until some time in '65, as a '65 model of course. Was your Twinn originally a single, 2-speed or Deluxe Twinn 5-speed? If it was originally a 2-speed or Deluxe Twinn 5-speed then it is a '65 since those models weren't available until then: Schwinn catalogs, 1961 - 1970 (267 of 765)

I've got several Schwinns that were built 1, 2 and 3 model years after their frames were made and have documented other examples with up to 6 years difference between frame and bike builds.

Sometimes you can get pretty close by looking for date stamps on some of the components if they are still the originals. If it has a 3-piece crank, look on the inside of the crank arms. Look at the underside of the seat where there may be a date stamp in the seat body. Front and rear hubs may have a stamp somewhere on them. It should get you within a couple months of the actual production date for the bike.

I may have misled you. When I say old I'm talking about maybe 6-10 years so it would definitely be considered modern. Sorry! I know some of you have had bikes for much longer than that but I don't think I have.

Since you are looking for information on recent models, they would have been made in China. I'm sure you will find a date on at least one of the components, probably the cranks. The other place to look is BikePedia. Open up the site, pick "bicycles" then start with a year and pick Schwinn for all the models for that year.
You can look up the Schwinn model name for the years around the time you think it was made and compare the component list and frame color with what is listed. They often change colors with subsequent years.

I did look at Bikepedia, and they didn't seem to have that model, it is probably lower end and from walmart so I just figured I'd see if there was a quick trick like "the first two numbers are the month, then the second two are the year!" If it's not super easy I'm not sure it's worth pursuing. I'm probably just going to use the frame as an outlet to experiment with mods eventually...it would be cool to have all the facts about it though so later on I can be like "and this was a 20xx Schwinn Sidewinder 2.x frame that I added a blah blah blah too, the original blah blah blah" and sound like an expert.

guess we can't have our cake and eat it too, ;-)

that is some seriously cool information...

Interesting, thanks for the info. It is a Deluxe 5 speed, or at least it was. I converted the drive train to a Shimano Nexus 8 speed.
The serial number is on the left dropout.