I don't cycle most of the year, so preparing for a tour, (usually approx 1000 mi. or so) I am most concerned about sore butt, Achilles tendons, and knees. I try to ride most everyday for 3 weeks a couple of hours a day to toughen up the "sit-a-pon", and I use a "stair master" daily for 3-4 weeks to condition my knees and heels. Other than that, as "eofelis" said, I take it easy for the first couple of days. A Workmate rode with me down the Pacific Coast from Vancouver Canada, to San Francisco California, and, despite my warning, didn't train very much beforehand thinking, as a long distance runner, he was in great shape. The reason we stopped at San Francisco, rather than continue to our planned destination, the Mexican Border, was his knees and achilles tendons. Both were so badly swollen he couldn't continue, and he missed a couple of weeks of work recuperating. On our next tour together, 2 years later, he trained beforehand, following my regiment, and had no trouble cycling from Fairbanks, Alaska down the Alcan hwy, going over mountain ranges etc. for well over 1000 mi.