I occasionally spanner for a 75 year old who still rides competively in 500cc Grass Track Racing.
He rides late 1920's and 1930's Rudges, which he's always raced since the 1950's.
So he's a vintage racer on a vintage bike.
You have to admire the design and toughness of a late 1920's Rudge, as it is a high revving (for those days), many modern features used on modern Japanese bikes. (Radial Four Valve Combustion, built up roller bearing cranks, etc.)
Rudge also were the first manufacturer to produce a truw Ton up 250cc road bike, their last bike, in 1938, decades before the Japanese made numerous claims to have done so.
Another modern everyday thing Rudge introduces was after market tuning kits, 'cos you'd obviously be tempted to race the bike once you'd bought one.
His most recent project is an aluminum cylindered Rudge stuck into a JAWA Type 896 Grass Track frame, which he intebds to race in modern bike classes. He figured that this was the way Rudge would have gone if they'd not had their factory destroyed by the Luftwaffe during the war.
Like he says about the Rudge Ulster, "Half the size of a Brough Sueriour but a lot better and faster!!" Having ridden one of his Ulsters many years ago, a bike with all the aftermarket factory goodies fitted, I can quite believe him.
I think vintage should be when the generataion that could buy the bikes new, when they were teenagers, reach retirement age (65) then those bikes should be deemed vintage.