I'm planning my first tour in mid-July, which gives me just over three months to make sure I've prepared myself. Since I don't know anything about bicycle maintenance, I thought it might do for me to learn a thing or two, especially if I know I'll be over a hundred miles from the nearest town (which won't necessarily have a bike shop in it).

Aside from a flat tire, what are all the common things people have had go wrong with their bikes? In theory, anything at all could happen, especially if you get into a serious wipe-out. But what are the more frequent problems?