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, bars or cranks.
Feel free to quote small parts of the information on this page, but copyright law requires be listed as the source of the information.
In this website, we credit the people involved in the understanding of these codes. (Naturally, for information provided by others, such as for the Campagnolo and Williams codes, the original source should be cited.)Ben writes: "Brakes and brake levers often have date codes on them.
The two sets of Dia-Compe brake lever bodies I checked had the four-number date code stamped inside the lever body (I couldn't find any markings on the levers themselves).
On a vintage bike in excellent condition (that apparently had a lonely existence in a garage) all of the components likely are original.Especially useful, and challenging to sort out and verify, was the Shimano code.Also gathered on this page are date codes decoded and generously provided by others.For example, the back of cranks are usually marked with crank arm length in mm, typically in the range of 165 to 185.Seatposts are marked with outside diameter, also in mm.