On the Eroica rides it is 1987 and older but I think the organizers are loosening that up a bit. To me it is more about the build of the bike . Lugged steel frame pedals with clips and straps, cloth or leather bar tape , at least 28 spokes, and brakes separate from shifters. There are bikes that are vintage ish like Rivendell that have vintage characteristics that definitely exude the vibe of the older bikes. I have heard some folks refer to vintage as something that is no longer in production.