I'm 50, and there some guys older than me come powering past, too.For a professional you’d be wrong. The TdF record for a time trial, is a sustained speed of about 55.5 km/h, for over an hour. When I was riding a lot I used to reckon on anything above 25mph as approaching the kind of speed needed to think about competence. Up hill, I’m going to guess at someone line Marco Pantani (Pantini?) on the Alpe de Huez doing something like 23-24 km/h. The fastest recorded TdF speed is likely to be 130 km/h or more, downhill, obviously.
All pro riders though, so no comparison. But there are young Brits capable of sustained 50 km/h riding. You may meet one of them on the road.
It's a lifetime of conditioning, though. Some of the buggers have been churning it out for years.
My lowest point came when, on the almost-flat, two of them came past me just as one turned to the other and said, "I really shouldn't have had that cigar last night."
Cheers, pal. Make me feel special.