Wow, good question. What *haven't* I learned?
I, too, have learned I can ride farther than I thought, that I am capable of far more than I believed.
I have learned that the more I ride, the stronger I get.
I have learned the unmitigated joys of a good road bike.
I have learned that Kool-Stops ROCK!
I have learned that Brooks saddles ROCK!
I learned that it is easier to climb with my hands on top of the bars than on the hoods or the drops.
I have learned that -for at least as long as I am in the saddle, I can be free. Totally free.