Cross Country is the most popular discipline and became an Olympic sport in 1996.
XC and Cross Country riding is filled with climbs and descents that are traditionally less technical than Enduro. XC / Cross Country riding requires a high level of endurance, and bike handling skills. XC and Cross Country is most often done on single track soft surface trails. In an XC / Cross Country cyclist will compete by age groups for the overall fastest
What you should expect Racing XC as a Junior, ROOKIE / Novice | CAT 3 | CAT 2 | CAT 1
Rookie/ Novice (Beginners should be able to ride 3-6 miles at a easy to moderate speed) CAT 3 (Should be looking at light conditioning and the ability to ride 9-12 miles fast) CAT 2 (Should be moderately conditioned and able to ride 18 miles faster) CAT 1 (This is a serious well-conditioned athlete who can ride 21 miles the fastest)
Traditionally have a shorter seat tube angle, shorter reach, and a shorter wheelbase than bikes made for other disciplines. This put the rider in a more aggressive position above the pedals maximize the ability to put power into pedaling efficiency. The steep angle of the front forks also adds better handling / steering on a XC bike.
XC bikes are commonly hard-tails and lightweight frames such as carbon fiber, titanium or buttered aluminum. XC Bikes usually have a suspension that is between 100 and 120 travel with less tread on 29in tires minimizing rolling resistance.