About a year ago I went cycling to Iceland for a couple of weeks.
I pretty much rode solidly every day of the 2 weeks with 2 days off. Some days, I was even in the saddle from between 10-12 hours.
I must have averaged about 80-100 miles a day.
I felt the weight drop off me and my muscles develop, and I felt great.
Anyway, when I got back home, I went about my normal routine which involved less cycling, and more sedentary activity. Then, after about a week, I cycled over to see some friends who lived about 10 miles away. I felt normal on the ride over to them and stayed there for a couple of hours before returning home.
When I got back on the bike, it was like a demon had taken control of me. I absolutely flew on the bike. My body was operating at a phenomenal speed and it just seemed to want to keep on going. I felt like I was on some kind of drug. I covered 10 miles on a 26" wheel bike, with suspension forks, in about 30 minutes.