To each their own. I love me a century - fast or slow - and I once desired to try longer distances, joining the local Rando club, and also thought that I'd do yet more after I retire. But I just cant sit in the saddle that long without something really starting to hurt. I do an annual ride from Minneapolis to Duluth with a large group of friends. it's 165 miles. Otherwise I seldom go over 100 and change.