I am often asked this question by family and friends. My usual answer is that Cyclocross (CX) is like a Cross Country race but on bicycles instead of running. It is a Fall and Winter sport and the events are held at parks, farms or other off-road venues that include a combination of grass and trail riding. CX races are for time, not distance and consist of multiple laps of a loop course that includes forced dismounts, mud, hills, sand, switchbacks, logs, stairs or just about anything else that the terrain or race directors can add to make it a unique and challenging course. Riders race against others that are similar in experience and ability levels and the events are typically 30, 45 or 60 minutes long.
Next, I am inevitably asked what type of bike is ridden. A mountain bike can be used and many riders do use them, but due to their relatively high weight and low gearing, most use a Cyclocross specific bike. A CX bike resembles the frame geometry and drop handlebars of a road bike but has some important distinctions. First, the clearances in the front fork and rear triangle are bigger to accomodate a CX tire. A CX tire has more volume than a road tire but less than a mountain bike tire. For off-road traction, a CX tire has a tread profile that is akin to a mountain bike tire. Secondly, the gearing is also CX specific. Normal gearing falls inbetween typical road bike and mountain bike setups. Third, the wet and muddy conditions of cross riding combined with the descents, turns and dismounts require more braking power than Caliper brakes. Cyclocross bikes use eitherCenter-pull Cantilever or Disc brakes. In addition to more stopping power, these brake systems accumlate less mud and debris. Finally, CX bikes rarely have a waterbottle cage installed as it interferes with shouldering the bike when negotiating obstacles. CX riders can be handed bottles from friends, family, teammates or crew. These are called "Hand-ups" and I have seen everything from water, energy drink, and my favorite: Pabst Blue Ribbon.
After giving that primer to those that inquire, I still sense that I have not been able to adequately communicate the spectacle that is cross. So here is a view of the sport from the inside. This is my fourth year riding cross and this is my first CAT3 race. I got destroyed but I still had a blast! See you at the races, and please, we need more cowbell!