Mr Floyd, you didnt mention at all where the trip is planned.
Is it biking through outer Mongolia or riding down the west coast of the States? You realize the reason I ask is completely from a logistical point of view, if your trip plans are in a developed country with more or less regular access to towns, campgrounds, stores etc, then its not an issue. If it is somewhere where security and whatnot is more of an issue, then that's another thing.
Put it this way, travelling on your own is a lot of fun also, and your interactions with folks is diff when alone, in a good way. I certainly found this when heading off on my own at roughly your age, many moons ago.