In cross-country mountainbiking, all riders start at the same time to complete a number of laps on a demanding off-road course, with lots of climbs and descents and a variety of technical challenges. Obviously, the first to cross the finish line wins. Depending on category, race-time is approximately 1-2,5 hrs. Unlike in road racing, team tactics normally do not greatly influence the final results.

The main difference between cross-country and marathon mountainbiking is the length of the race. Where a typical cross-country race lasts for 2,5 hrs. maximum, a marathon race takes somewhere between 3-10 hrs. for the winner to complete. Ideally, the course is just one long off road loop, but there are many cases where the riders have to ride the course 2-4 times. A marathon course consists of numerous hard climbs and gnarly descents, as well as many other technical challenges, just like a cross-country course.