Date of Manufacture for Bicycle Components

The date of manufacture of a bicycle's components can often be used to determine the date of manufacture of the bike itself. Some bike components have a date code cast or stamped into the piece. This clearly is when the component was made and not when the bike was made, but unless the component or bike manufacturer had lots of stock lying around in inventory, the date should be a fairly good indication of the year of the bike. At least it would be the earliest date that the bike could have been made. Of course, all this assumes the bike has the original component.

A date code is marked on most or all SR seatposts. Trek owner, Larry Osborn, made this observation and suggested this as a way of dating a bike. Fueled by this first realization, we both are working to sort out other codes.

SR (Sakae)

Below the insertion mark on SR seatposts (and Sakae posts) is a stamped mark, such as F-84. The number is the year of manufacture and the letter appears to be the month of manufacture. In the example, the "F" indicates the sixth month, or June.

Most (or all) SR right crank arms also have an open date marking, either stamped or cast into the arm. The date is on the back side of the arm near the spider of the crank, typically of the form of the two-digit year above a letter, apparently representing the month.

SR stems usually are marked with the same date code. It appears near the insertion mark. An exception is the SR Royal stem, most or all of which, have no code.

For Treks, the SR date markings are especially important. Virtually all of the Treks not equipped with Campagnolo or Shimano Dura-Ace components, started life with some grade of SR seatpost and may also have SR stems or cranks. Even those equipped with Suntour Superbe components usually had SR seatposts.

Campagnolo Components

The dating of Campy components (hubs, rear derailleurs, and cranks) is described at the bottom of Chuck Schmidt's excellent Campagnolo timeline:
http://www.velo-retro.com/tline.html

Shimano

Shimano components have a two letter date code, in the form XX, where X is a capital letter. A friendly Shimano representative told me the code is not public but he was able to answer some of my questions. One letter is the month, the other is the year. He thought all Shimano components use a common code. Some Dura-Ace seatposts are stamped with a two letter code of the form X-X, where X is a letter. The Shimano representative believed this is the same meaning as the more typical form XX.

The date code is stamped (or cast?) into the component and appears separately from other markings. It is easy to confuse the date code with the alphanumeric model number (e.g. "HB-6500" marked on an Ultegra hub). The code is on the outer flange or the center shaft of hubs, on the backside of crank arms, on the backside of brake arms, and below the insertion mark on (at least some) seatposts. On crank arms, the letters may appear as about 3 mm tall and enclosed in a circle.

We believe the first letter represents the year and the second is the month, where A is January and L is December. Our best guess, from a look at parts and bikes we have, is that A is 1976 and the letters proceed sequentially from there: K is 1986 and Y is 2000. Is this right? We would greatly appreciate your feedback on this - please contact me.

Strong Seatposts

Seatposts made by Strong typically have a two digit numerical year date stamped into the post below the insertion mark.

Derailleur Dates in "The Dancing Chain"

The rear derailleur can often be dated to a few years by referring to the book "The Dancing Chain - History and Development of the Derailleur Bicycle", by Frank Berto, Ron Shepherd and Raymond Henry, 1999. The Appendix gives dates of initial manufacture for the vast majority of derailleurs made from 1920 to 1999.

Request for Information

This discussion is a work in progress. Other manufacturers of bicycle components have date marks on their pieces. Unfortunately, many of these are coded, and require some additional knowledge to understand the code. If you know of other components that are marked or coded that can be added to this list, please contact me.

 

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