The short answer is that it takes a bit of detective work to date your vintage Lotus. Many bike builders code the date of manufacture into the serial number of the frame, but Lotus serial numbers seem to be proprietary and we have yet to break all of the codes.
Lotus literature is difficult to find and we don't have a catalog for every year of production. We are constantly searching for information and many readers have helped find old catalogs and sales literature. We'd like to thank Joe B, Ryan L, Eric P, John C, and Kent M once again for taking the time to scan and copy Lotus information for us.
If you have access to any Lotus literature or memorabilia and would like to help the website, please contact us.
Hopefully, using the Model pages on this website will at least help narrow down your choices and target you within a year or two of when your bicycle was made. Many pages have photos and specification charts that can be used to narrow down the year of your bike by using significant details as a comparison. For example, some bikes were made for a few years, but were only available one year in "Raspberry Pink".
We also use the term "generations" when it comes to dating Lotus bicycles, as sometimes a specific model, like the Excelle, was made for 10 years. During those 10 years the model changed significantly enough to be considered a different generation four times. Knowing the generation your model falls in will help narrow down the year it was made.
If you check out the Serial # Chart, you may be lucky enough to have a serial number close to a bike that has already been dated. The two-letter prefix found on many serial numbers does seem to represent model years, or ar least production runs. For example, we believe the prefix KY represents 1980 production for at least the Legend and the Classique.
Most Tsunoda-built Lotus serial numbers are stamped onto the underside of the bottom bracket and consist of two letters followed by five, six, or seven numbers (AB12345++). It seems that later model bikes have more numbers than the earlier bikes. This may be an important clue to dating a vintage Lotus. Some bicycles have been observed with serial numbers stamped on the seat tube near the bottom bracket. We are collecting a list of models and serial numbers in an attempt to make heads or tails out of the numbering system. Please view the chart and feel free to submit your own information at the bottom of the Serial # Project page.
If you have a Pacific Cycles built Lotus Elite, Elan, Special, Sprint or Prestige your serial number will begin with the letter P, as in the example shown below on the Lotus Elite. P stands for Pacific Cycles. The second number represents the year of manufacture and the third and fourth number, the production week. The final numbers are the individual frame numbers. So number P3151234 was the 1234th frame number built during the 15th week of 1983.
Some Lotus bicycles built in 1986-88 use a Y6C1234 style code. The first letter is possibly a vendor code, the second number is the model year and the third letter is probably a fortnight code. C represents the 3rd fortnight of 1986 production.
We know that Lotus bicycles were built by many different factories to Lotus specifications. If you view the chart, specific numbering styles are starting to appear. Each different numbering style may represent a different factory. So far we know that Lotus used Tsunoda, Pacific Cycles and Maruishi to make their bikes.