I did a 44 mile ride today solo, out the Cedar River Trail to Maple Valley. This is the same distance coincidentally as my longest ride, but I was on my own, and I didn't take any breaks. Even though a lot of the ride was flat, it was pretty windy, so I'm beat. As it turns out, it really does make a difference riding in a pace line with others. I worked a lot harder today than in my previous rides. Sucking down two Gu packs along the way seemed to help. 3:07 ride time.
I'm also still dialing in my gear. I've been trying out a new saddle; not sure if I like it yet, but it's definitely better than my old one. I also installed SKS Race Blade Fenders last week; good thing since it was raining for part of my ride. I'm not all muddy now (well, not as much).
Anyway, still lots more miles ahead and time in the saddle before I feel confident about successfully completing STP.