Firstly – where are you going to be riding it? While most mountain bike advertising shows extreme sports aficionados bounding over logs, rocks and canyons to punk rock beats, the vast majority of mountain bikes, when ridden at all, are ridden on prepared trails. If this is going to be how you're riding, you will want a bike that has got a moderately stiff frame, and a good shock absorber system.
If you plan on doing competitive off-road racing, you will want a bike with stiffer construction. The stiffer the frame, the more efficiently it transfers the power from your legs into the frame and into the rear wheel. You'll also want to forego most of the extras – each one ads weight, and when you're pedalling your bike up a hill, that extra weight adds up.
Most mountain bikes sold today have aluminium frames; aluminium is lighter than steel (about 40% lighter all told), and with aircraft grade and double butted tubing, at least as stiff. High end mountain bikes use carbon fibre frames, or other, more exotic materials to reduce weight and keep stiffness up.
There are specialist mountain bike designs out there, such as downhill models, and ruggedized versions. Neither of these are suitable to general purpose riding. For example, downhill racers are heavy tanks of a machine, and getting them to the top of the hill is something you do with a truck, and then ride them down from there. They are the cycling equivalent of downhill skis, and are just as specialised.
If you're looking for "off-road touring", we recommend bikes, like those made by Merlin, that are geared towards some stiffness, and general durability and maintainability. Most mountain bikers, as mentioned above, don't ride as if they're starring in a Mountain Dew ad; they're ridden on trails to enjoy nature while getting some exercise and most importantly comfort.
Once you've got your bike, take the time to get it fitted properly to you – this means adjusting the seat height and the handlebars appropriately. The seat height is right if your knee is at a bit under a right angle when the pedals are parallel to the ground. The handlebars are set at the right height when there's a 45 degree angle from your shoulder to your elbow. Most of the people who complain about back and hip pain from riding a bike are suffering because the bike wasn't fitted to them properly.
Once you've got the basics down – a mountain bike that's comfortable to use, and suits the kind of riding you'll be doing, then it's time to look at added features, like stabilization controls, shock absorbers, and other details. Like most sporting equipment, the more you get into the competitive aspect of things, the higher the price tends to climb.
By: Derek Rogers