If I am only going to be out a night or two I pack for a week. If I am going to be out for a week or more I pack for a month. Plans change. This is not backpacking and its not a race.
I have never been sorry I had too much food, water or dry socks. If my pile of stuff is more than I want to pack on my bike, then its trailer time.
http://thefrugalhamstercyclist.blogspot.com/