In the truest sense of the word, mountain bikes are built solely for "off-road" riding . . . forest trails, mountain trails, and cross country trails.
How Does A Mountain Bike Differ From A Street Bike?
Frame - Mountain bikes are built to be durable and maintain functionality under very rugged conditions. To maintain this durability under rugged conditions, mountain bike frames are constructed of much stronger material than the normal street bike frames. True mountain bike frames are titanium.
Ground Clearance - Mountain bikes are also built with a higher ground clearance, making it easier to negotiate rocks, logs, and ruts, etc.
Tires - Mountain bikes generally run with wider, knobby tires providing more substantial grip and traction on varied terrain. Even greater traction and stability is provided by these tires because they carry a lower pressure.
Handlebars - Mountain bike handlebars are generally flat and extend straight out from the stem forming a wider grip, usually about shoulder width. Thus the rider sits upright with better vision and has more stable control of the bike.
Gears - Mountain bikes generally have 16 to 27 gears because of the varied terrain they are called upon to negotiate. However the gear range on mountain bikes is much lower than the gear range on street bikes. Mountain bikes are built for power to negotiate steep climbs.
You Have A Decision To Make...
We have just covered the basics of a true mountain bike, a bike built for trail riding. Generally speaking, a good, durable mountain bike starts at about $600 and goes up from there.
However, for the most part, people are not looking to be a mountain bike enthusiast, they do most of their riding on the street, and only occasionally ride light trails.
If you find yourself in that group, perhaps you need to be looking for a mountain/street bike combination.
Each specific bike will have its own blend of mountain to street features.
However, one thing they all have in common is a mountain bike frame. Many of these bikes offer a mountain bike frame built of aluminum. These aluminum frame bikes are lightweight for street use, however the aluminum frame limits their use to light trails only.
These mountain/street combination bikes utilize the mountain bike handlebars, giving the rider an upright position.
Some of these combination bikes offer disc brakes front and rear, steel frames, twist grip shifters, and shock absorbers front and rear.
Tires can also be changed to meet the needs of the rider. Smoother tires for street riding, knobby tires for trail riding.
How To Select The Proper Bike For Your Needs...
How will you be using the bike?
If you will be spending more time on the streets, you'll want a bike with more street bike features, and visa verse for mountain bike features.
Go to a local bike dealer and test ride, checking out a variety of features. Test ride bikes on each end of the spectrum so you understand the characteristics of certain features. If you can, do more than just ride around the parking lot. Spend a few minutes riding on trails, over rocks, and gravel roads.
Make a conscious effort to check out tire tread performance under various conditions. Determine the blend you need between smooth and knobby.
Check out shifters. There are two major systems on the market 1) Rapid Fire, and 2) Grip Shift. Rapid Fire works from buttons/levers under the brake lever. With one finger or thumb, the rider works up and down the gears. Grip Shift works like the throttle control grip on a motorcycle, the rider changes gears with the twist of a wrist.
Be conscious of the pedals. Note which pedal type feels the most stable and secure to you.
Make sure the seat is comfortable. The seat can always be padded later if it is uncomfortable, however choosing a comfortable seat from the beginning will eliminate future problems.
Relax, have fun making your decision. Discover everything you can about bikes, if possible, test ride.