I'm 61, and I ride about 4000 miles a year on my three singlespeeds -- on road, trail, and gravel. I've raced singlespeed MTB, CX, and BMX. It's not always the right tool for the job, but that's part of the fun -- they make bike riding less about the bike and more about the riding. While I own and appreciate geared bikes as well, I think every well-rounded rider should have at least one singlespeed in their quiver.