I posit the following, that town bikes connect riders with people, mountain bikes connect riders with nature, and road bikes connect riders back to themselves.
A town bike is social, about sitting up, b-r-r-ringing that bell, and smiling at people. The town bike connects you with others. A mountain bike is for communing with nature, though not the way bush walkers do. Mountain biking is like stuffing all the pomegranate seeds in your mouth all at once, rather than eating one seed at a time—the way bush walkers eat. Then, as you speed up, mountain biking becomes a mouth full of moon-rocks. Ca-pow! That's how a mountain bike connects you with nature. Road cycling takes the rider into a solipsistic space, where reference is made back to one's heart rate, their breathing, riding position, and the uniform engagement of hundreds of muscles each nurtured for years for the moment you sprint, ride away, or attack on a hill. Whether via heart rate monitors, or the zen state I look for when I am racing, road cyclists are looking back into themselves, asking if they're improving, in form, or if mortality is slowing them down.
A Freudian analysis of the above, explains why the marketing and blogs associated with town bikes makes so much use of sexual imagery, and why the word "chic" is so often bandied. Town bikes satisfy our craving for social intercourse, which in Freud's mind simply meant intercourse. That is to say, town bikes are referring to Eros. In Freudian terms, mountain bikes are appealing to our subconscious death wish, or the spell of Thanatos, however you might like to describe it. Road bikes, as everyone knows, satisfy a longing we each have to see our reflections, in the manner of Narcissus. If you understood any of that, I welcome your comments.