Cyclocross, "CX" for short, is a fun and unique type of bicycle racing. To understand cyclocross, pretend that road-bike racing and mountain biking hooked up for an irresponsible night of passion. And, they had a baby. Then... they got their kid drunk.That drunk child is cyclocross.

You can do cyclocross on a mountain bike. But the best riders will be on bikes made specifically for cyclocross.A cyclocross (CX) bike looks like a road bike. The handlebars and shifters are like a road bike. But the frames are stronger. The frame geometry is tweaked to improve bike handling in bumpy spots and tight turns.

The wheels on a CX bike are stronger so they can hit rocks and roots. Tires are bigger than a road bike -- although still only about half the diameter of a standard mountain bike tire. The tires have tread for traction in snow, mud, and sand.Cyclocross bikes may use disc brakes or cantilever brakes. Standard roadie brakes would get clogged with mud.

When getting started with cyclocross, some racers will put small tires on their racing mountain hardtail. That's fine. Riding your mountain bike is a cheap way to test the waters to see if you like cyclocross.Here's a thought: borrow a CX bike from a friend who'll be racing later in the day. Once you're addicted, you'll want a CX bike.

To create a cyclocross course, the promoter will usually select a park that includes some wild territory. Mountains are generally avoided, because the object is to zip around at lightning speed, not to grunt uphill forever. There needs to be plenty of parking, because several hundred bikers may show up.

A good cyclocross course will have plenty of turns and varied terrain. The loop will be usually be just over a mile in length. The route will be outlined with barrier tape and cones.An absolute requirement of CX are barriers that make you jump off your bike and jump back on again. It might be a log, a ditch, a set of stairs, or barriers made specifically for cyclocross racing.

Sometimes the barrier lets the best riders jump over it. But dismounting, jumping the barrier, and hopping back onto the bike are critical cyclocross skills that riders will practice. Expert racers are so smooth and fast that you hardly notice they got off the bike.

The CX course will hit as many different trail surfaces as possible. There will be some grass, some smooth trail, some sidewalk, some pavement. But expect an occasional helping of sand, cobble, mud, roots, and if you're lucky, snow. The idea is to serve up challenges to your bike handling.

Where possible, a cyclocross course will also include a "run-up" which is a hill that's too steep or loose to ride. And just to keep the hotshots honest, there's often a barrier at the bottom of the hill so you're forced to run up.

The best cyclocross courses have plenty of spots to pass. But there will be occasional choke points to make things interesting. Make your move to get there first.

Racers sign up for a category based on their ability. For example, Men A are the blazing fast experienced racers, while Men C are beginners. There are Clydesdales (heavier racers) and Masters (old guys) and other special categories based on age, sex, and ability.Popular cyclocross events will have multiple races about an hour apart. The idea is to have riders of similar speed and aggressiveness on the course at the same time. Within each race, there may be several "waves" of racers. For example, Masters 55-plus, Men C, and Clydesdale might be sent out a minute or two apart.

Racers who are in the lead for the season will be called up to the front row as each racing category is organized at the start line. This is called staging.When the official says "go," racers take off on a wide area of the race loop that spreads the group out as the faster riders sprint ahead. You'll be racing for 40 to 50 minutes, depending on the category.

CX is a very intense type of racing. You aren't racing for a long time, but you're going all out. You're not saving anything. After each turn or barricade, you sprint.Racers will make several laps around the loop. But you won't really know how many laps until the race is half over. Here's why.

A cyclocross race has a pre-set time, not a set distance. Once the fastest riders have finished a couple of laps, the race officials calculate how many more laps will be done in the allowed time. Then they call out the remaining laps for all riders. But once the fastest riders cross the finish line on that final lap, all riders are finished the next time they cross the line. If you were lapped, tough. You're done.

Cyclocross season is typically in the fall. The cool temperatures let you go all-out without cooking. And later, when the ground is slimy and there's snow on the roots, that's even more fun!