Another perspective is that biking a century is for the cyclist to have a goal of doing a more difficult ride than usual, to test the cycling fitness with respect to age and health. But it doesn't have to be a century, because a 30-mile ride can be a test of fitness with respect to age and health also, depending on the individual. Now that you know about your eyes, set your goals for next year, and the length of the rides will be related to your health during 2012. A half century or metric is just as monumental to complete as a full century.

Here is what I mean. On September 10 I was one of four Tour de Cure cyclists who volunteered to man Rest Stop #2 for Step-Out Portland, the event for walkers to raise money for the American Diabetes Association. The rest stop was at mile 3.5 of the longest route of 6 miles. Many of the walkers were insulin dependent diabetics, and though for us, the volunteers at the rest stop who are distance cyclists, a 6-mile walk is hardly any effort, for these diabetic walkers completing 6 miles was monumental, equivalent to the volunteers biking a difficult century. We were proud of the walkers, out there in the heat doing their best.

That is what it is all about. The fitness fluctuates from year-to-year and the biggest factor is health. A half century or metric one year is just as significant as a 30-mile route or a full century on another year. In other words, like others said, there are more centuries in your future and if not, there are shorter bike rides or other activities to test the boundaries of your fitness. Good luck!