Hmm, things I learned on my first tour (Katy Trail in mid October, when we suddenly had a cold snap that week):
1: If I can help it, I will never ride in 40 degree rain ever again. Riding in the heat and riding in the cold are two VERY different sports.
2: Flat bar handlebars with bar ends suck. They ruined my wrists, and it took a couple weeks of not riding for them to recover.
3: My Walmart mountain bike, although it held up well, was heavy as hell and the knobbies sucked up wet gravel and clay from the trail and became unbearably slow. CCrew's comment about the "wet cement" is 100% accurate.
4: There is virtually no limit to the amount of calories I can put back while bike touring. Food was not the bottleneck.
5: I never ran out of water with a camelback and one bottle. Granted, there's a town every 15 feet on the Katy, but on that trip... water was not the bottleneck.
6: My leg muscles would start to hurt, but they never gave out. Fatigue was not the bottleneck.
7: My lungs would start to hurt, but they never gave out. 02 was not the bottleneck.
8: MY FRACKING KNEE, however... *was* the bottleneck. It gave me nothing but problems. Next time, I'm packing about 5x as much ibuprofin and wearing my neoprene compression thingy from the start.
9: GET ON THE ROAD EARLY. Somehow time distorts on the road, and 50 miles at 10mph requires more daylight than you have.
10: Those plastic rain ponchos are a great way to overheat. Given the fact that they caused overheating in 40 degree rain, I don't think I'll use them again.
11: Setting up camp in the dark sucks. Camping in cold rain sucks. Setting up camp in the dark in cold rain is worse than the sum of its parts. A great example of synergy at work.
12: Despite (in some cases... *because of*) all the misfortune, I had a *BLAST*! I love bike touring, and that trip inspired me to build my touring bike. Moral of the story: stuff happens. Full stop. You can't prepare for most of it, and you can't predict any of it. When it happens, get it handled, and get on with having fun.