On the other hand, it is just as hard to avoid the temptation of the ultra-light bike. The benefits of light weight are undeniable, but a novice rider will find XC racing bikes can be difficult to control when the trail gets rough.
XC Racing Bikes
Often called Cross Country bikes, XC Racing bikes are designed to tackle a mountain from the bottom. Lightweight and efficient, XC bikes often sacrifice comfort and control as luxuries you can’t afford when racing to the top.
XC bike frames are either hardtail or short travel, semi-active suspension designs. Long and low, XC bikes put the rider in a stretched out position. Best suited to gradual terrain, XC racing bikes are popular in areas without a lot of rocks and roots and among competitive riders.
If your idea of mountain biking is fitness and endurance you may want to consider a XC Racing bike. If you consider the best rider the one who made it to the top first, then your choice is made.
XC Trail Bikes
Often called all-purpose, XC Trail bikes are what most people think of when they hear the term “mountain bike”.
XC Trail bikes are designed to climb with control and comfort and descend with speed. With active suspension, knobby tires and low gearing the XC trail bike is slightly less efficient than an XC Racing bike but can be more enjoyable to ride downhill. As terrain gets steeper, trails tend to get rockier and the ultra-light XC Racing bike may ride roughly, but the XC Trail bike is right at home.
If you like the idea of challenging yourself on a rocky climb, enjoy extended singletrack descents and want to battle it out with your friends going uphill or down, an XC Trail bike may be for you.
Some riders just need more. As adventures get longer and trails more remote, many riders see increased value in reliability and downhill control.
The bigger tires, plush suspension and powerful brakes of the All-Mountain bike are an insurance policy against accidents and mishaps and can be just plain fun to ride. With geometry suited to steep terrain and small drop-offs All-Mountain bikes can inspire confidence, however, on more mild terrain they can feel sluggish.
If you are an all-day adventurer or ride harsh trails you may be an All-Mountain rider.
Freeride bikes are designed to ride the most extreme types of terrain. Steep chutes, large rocks and roots, big jumps and drop-offs, and just about anything else, natural or man-made, that you can imagine.
With only the occasional concession made for even the thought of riding uphill, freeride bikes are mountain biking’s version of monster trucks. Blurring the line between bicycle and motorcycle, bikes with eight inches of rear wheel travel, three inch wide tires, and eight inch diameter brake rotors are commonplace.
If you are attracted to the challenge of going big and see mountain biking as a source of individual expression, Freeriding will appeal to you. And what does any extreme athlete need? Well, a Saint to watch over him, of course.
taken from bike.shimano.com