It is very important for a mountain bike to have a proper shock system including a full suspension. It is important because it helps absorb the shock when going over rugged terrain and helps to provide a smoother ride. A mountain bike with a full suspension will have a rear suspension along with a front suspension. If a mountain bike has a solid rear fork and a suspension at the front they are often called hard tailed. Bikes without a suspension at all tend to be fairly lower end mountain bikes.
Mountain bikes with both descending and climbing ability are usually ideal for cross country riders. The movement in the rear suspension system is only about 4 inches so that it does not cause a problem when trying Online Generic pharmacy to climb hills. Cross country bikes have 28 gears as standard which provide a wide greater options for travelling over different terrain.
If you are a more technical mountain bike rider you will probably need a trial bike as they are a little more robust. The movement in the suspension can be between 4 inches and 7 inches. Uphill pedalling will be more difficult but you will in general get a much smoother ride. Riders of mountain bikes have to weigh up whether they need a smoother ride against decreased pedal efficiency. All terrain cycles is a great place on the web to look for Trek Track Bikes.
Mountain bikes which are specifically designed for going downhill can have up to 8 inches of movement in the suspension. These type of bikes are generally design for downhill racing. They are difficuly for pedalling uphill but have a lot greater handling when going over difficult terrain downhill.
A dirt jump bike is another version of a mountain bike. These only have a front suspension and are used for flying over jumps. As they come with 16 gears it helps the rider to build up speed quickly.