The typical 'cross course consists of a 1.5-2 mile loop of varied terrain, including dirt, pavement, steep run-ups and off-camber turns. Natural and artificial barriers are often used to force the riders to dismount and remount their bicycles at speed. The races are timed events which last between 30 and 60 minutes each, depending on the riders's age and/or ability level.

For a more detailed history, see the Overview of Cross by cyclingnews.com, or straight from the horse's mouth by the Union Cycliste Internationale

Cyclo-cross Q & A
What type of bicycle is used for cyclocross?

Though mountain bikes are acceptable, a 'cross bike is essentially a road bike modified to withstand the rigors of off-road riding. Modifications typically include the addition of knobby tires, and cantilever brakes. A frame built specifically for 'cross includes a raised bottom bracket for increased ground clearance.

Why do people race 'cross?

Due to the running sections and constant "on again/off again" nature of the sport, participants find that racing 'cross improves their bike handling skills and provides a more well rounded workout than regular road or mt. bike cycling. More importantly, riders enjoy the typically low-key, friendly competition they find in cyclocross. Though there exist national and world cyclocross championship events, 'cross remains a relatively fringe sport with a dedicated following who race 'cross year after year.

How does one learn cyclocross?

The Santa Cruz County Cycling Club offers training clinics, taught by experienced 'crossers. The clinics include breakfast, a lecture on technique and equipment, actual practice dismounting and remounting the bicycle, and a pre-ride of the course with analysis by the instructors.