I'm old and fat, but even after not cycling much In a few years I could start and complete a 20 mile ride give me a month cycling every day and I can reach 50 a day, give me a 2nd month and less hilly than Nashville I can do the 50 without stopping except to pee. This makes little blue pills unnecessary. heh heh however I don't cycle on road bikes at 20 mph, it's a mountain bike at 12 mph average.