The first requirement for a would be mountain biker is to obtain a bicycle. Some mountain bicycles are traditional in that they feature thick rugged tires. These bikes are ideal for off road rough terrain biking. There are also mountain bikes that feature thinner less rugged tires. These bikes are really hybrids between mountain bikes and touring bikes. The advantage these bikes offer is they weigh less than traditional mountain bikes. If you are planning on biking on paved roads or paved bike trails or even on trails with light obstacles such as roots or rocks these bikes (hybrids) may be ideal for you.
For the technical mountain biker who enjoys riding over rocks, tree roots, and other natural hazards the thicker tired mountain bike will offer a safer more satisfying riding experience. As a fledgling mountain biker you should not as a general rule choose the most expensive mountain bike available. As a general rule what you are paying for is either an enhanced ride through the use of front and rear shock absorbers mounted over the front wheel and under the seat of the bicycle or a bike frame constructed of the very latest space age medals and so lighter than traditional mountain bikes. The only times I can see spending extra for an more expensive mountain bike is if you suffer from arthritis, have had a carpal tunnel or other operation such that an enhanced shock absorbing system will benefit you. Also if you enter mountain biking races than a more lightweight mountain biking frame will benefit you.
Right after selecting a mountain bicycle, I suggest you select a bicycle helmet. No one should engage in the sport of mountain biking without a helmet. Many states have passed laws requiring that both children and adults wear helmets when they ride bicycles. The natural hazards inherent in the sport of mountain biking make proper headgear a necessity. Most bike helmets today are made at least in part of hardened Styrofoam with plastic outsides and are very light in weight. Inside the biking helmet there is usually stamped the safety results that independent testing organizations have obtained in testing the helmet. These should be examined carefully.
In addition to needing a mountain bike and a helmet you will need to transport your bike to where you wish to ride. To do this, you will need a bike rack. There are 3 major types of bike racks available. These are roof racks, trunk racks, and bicycle hitches. A roof rack fits tightly on your car's roof. The bikes are clamped tightly to the rack. A roof rack has the advantage of allowing the trunk of your vehicle to be readily accessible. This can be an important advantage on vacation trips. The two most prevalent manufacturers of roof racks seem to be Thule and Yakima. I have also seen racks with Sears Roebuck and Volvo trademarks attached to cars also. One major disadvantages of a roof rack is that carrying your bikes on top of your vehicle adds height to the vehicle. You need to be very conscious of this when you are using your vehicle with bikes attached on top and about to pass through a tunnel, park your car in a parking facility with a low roof, or even park your car in your own garage. I am ashamed to admit that I have forgotten that my bikes were attached to my roof rack as I entered my own garage on more than one occasion with expensive consequences of my absent mindedness!
Some other possible disadvantages of using roof racks are that lifting your bikes up to fasten them to the roof rack puts extra strain on your back and may cause back injuries. Another disadvantage of roof racks, is especially with today's sport utility vehicles, you may need to carry a step stool in your vehicle when you are cycling in order to lift the bikes high enough to fasten them to your vehicle. A trunk rack as the name implies, has clamps which fasten tightly to the trunk of your car. Trunk racks are clamped to the trunk of your car before you begin your biking trip and are removed after its completion.
Trunk racks may be ideal when you are carrying bicycles for young children that are not heavy or large. As the size and weight of the bikes increases. the added size and weight may bend or dent your trunk and impede accessibility to it with a trunk rack. A hitch rack is attached to the rear of your vehicle on a more or less permanent basis. The bikes are fastened using heavy rubber clamps. A hitch rack offers the advantage of not increasing the height of your vehicle or denting your trunk. Hitch racks do increase the length of your vehicle and restrict visibility in back of your vehicle. Furthermore, a hitch rack with bikes attached makes the motion detector on my Ford Explorer useless. With all of that said, I myself use a hitch rack.
Another piece of equipment that is a necessity for mountain biking are water bottle racks. Regardless of the season, it is important to have an ample supply of water with you when you are mountain biking. Water bottle racks come in a few styles and can be easily attached to your bicycle. If you will be cycling for more than a few hours, you should take food with you as well. Food for lunch or snacks can be carried safely in many types of bike bags which can be fastened by means of velcro straps or bungies (single or double width elastic straps). If taking food in a bike bag is likely to be a part of your mountain biking experience, you should ask your bike store to attach a sturdy rack to your bike to which you can attach a thermal bag to carry your food in.
I also suggest carrying a few other things with you when you ride. A universal bike tool to allow you to raise or lower your seat, an extra inner tube for your tires, and a small bike air pump can all come in handy, help you meet your little biking emergencies, and increase your enjoyment of the sport of mountain biking.