You know you're getting old when your wife says "hey, let's go to the mall and walk" and you think "sure, it's 20 degrees outside and I don't feel like getting dressed for a ride. On the plus side, I was riding with a guy on the commute home who was riding a nice road bike. At one light he mentioned how "I could ride that fast on a mountain bike when I was your age too." I thought he looked younger than me so I asked how old he was. By my math, he's 9 years my junior. Add that to the 1.3" difference in tire width and I feel pretty good about the ride.