Forth month of dating
Swaps also can be made as the bike falls out of favor, or is being sold, where the higher quality components are traded for lower quality ones that the owner had onhand.
Some bike parts 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.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.
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