This Saturday may be the one rare day when bicyclists rule the road, at least in selected parts of 100 Chinese cities. Manuela Zonensein, who recently returned to Beijing to find Chinese going car-crazy, explains why:

A dozen years ago, my adolescent mind could hardly grasp China's reality. That was my first trip East, and I came away with important wisdom still with me at present. Dumplings are delicious. Clothes and sneakers are disgustingly expensive in New York. And the world might be less inclined toward conflict if bargaining were an art form permitted everywhere and pursued as enthusiastically as it is here.

But one thing I was entirely unable to comprehend in 1995 was this: how on earth did swells of bicyclists successfully navigate the tide of pedalling wheels along China's city streets? Unfortunately, I may have returned to Beijing a little too late to find out.