When I'm fit I can keep up with the cat. 2s on my '82 Bianchi with Super Record. I honestly don't feel it's any handicap at all on flat roads, although in a criterium with constant shifting I would be at disadvantage. I am sure the bike is a handicap in the mountains, but my beer gut is more of a handicap. I would lose by less on a modern bike, but losing is losing.

Now, some 30 pound POS with gaspipe tubing and components with unpronounceable names is a different story. I do not understand why any enthusiast would ride one of these monstrosities, let alone why anyone could actually be excited about collecting them and writing it up on the internet, but there are lots of things I don't understand. Regardless, I don't think Greg LeMond could keep up with a decent bike rider while riding one.