PALO ALTO, Calif.

On the hour they come, great clouds of cyclists pulsing between classes along the street called Serra Mall  the main axis of Stanford University  like so many slowly charged particles in a physics experiment.

Campus is flat enough  and large enough  and the weather so brilliant that nearly everyone cycles. And whoever all these cyclists are, as individuals, their individuality is burnished by the bikes they ride and by the way they ride them. It’s as though the bikes are only partly transportation, as though they were really machines for differentiation.

And what aids the differencing is that few people wear helmets, and everyone is wearing ordinary clothes  none of the sleek and gaudy costumes you see on cyclists pumping through the peninsular hills and whistling down Sand Hill Road to the Caltrain station. They are themselves on wheels.

There is a deeply pleasing randomness about the campus cyclists, as though one morning university officials had assigned a bicycle to every member of the Stanford community, come as you are, without considering for a moment matters of fit  or fitness.