I'm still pretty out of shape, but approached 30 miles on my ride on Saturday. What's an appropriate time for a century? At first I thought it was the cycling equivalent of a marathon, but considering I'm averaging 12 mph, I realized that 100 miles is an 8 hour ride.

I really have no idea how to approach this level of mileage. But my girlfriend is doing a half marathon, and running is too much for my knees. I feel like I need to do something equivalent on the bike, which I really enjoy. But I'd rather not die.