vintage 27" cyclocross frame (questions)
i recently picked up a vintage steel cyclocross frame. it's made by Vagacini (of which i've found very little info online) and is branded "cyclo cross" on the top tube and has Reynolds 531 stickers on the frame and fork. these decals all appear to be original and i have little reason to believe that this wasn't built to be a cyclocross bike, probably in the 70's by the weight, lugs and fork crown.
the frame has cantilever brake bosses and definitely is built for 27" wheels, not 700. i have a nice set of wheels for it, but i can really only find 2 manufacturers that produce a knobby 27" tire. i tried searching for knobby 27" tubulars and found even less. even looking around for past ebay auctions revealed little, new or used.
i know cyclocross started loosely in the early 1900's, and that it became an official sanctioned event in the 50's. And i know it wasn't until the 80's (roughly) that manufacturers had made the full switch over to fully 700c bikes. So that means there had to be at least a couple decades that people were racing cyclocross, as an official sport (presumably with tires built for that purpose), on 27" wheels. is that a fair assumption? where did they all go?