Mountain Bike Frames
Then centerpiece of any good mountain bike is a good frame. So it is important to understand the mountain bike frame before buying a mountain bike. Of course in most cases, good mountain bike frames will cost more. But there are many different aspects of a mountain bike frame that determine its quality. For example, a high-tech alloy frame that is sturdy and weighs very little will cost quite a bit. On the other hand, an old-fashioned, heavy steel bike frame, while relatively sturdy, wouldn't cost much. However, serious mountain bikers don't want to have to deal with a heavy bike while maneuvering through tough terrain. So really, the right mountain bike frame design for you will depend a great deal on how you use your mountain bike.
Modern Mountain Bike Frame Composition
If you're just getting into mountain biking, a cro-moly bike frame is an affordable frame that offers plenty of durability. Cro-moly produces a heavy steel frame, though with some elasticity to it when riding over very rough terrain. It doesn't cost much to get into mountain biking if you purchase a cro-moly model, so most mountain bikers have started this way. Many leisure mountain bikers never find any need to upgrade to a lighter frame. Obviously, competitive bikers don't bother with cro-moly bikes.
An aluminum mountain bike frame has very little weight to it and is quite affordable. However, aluminum frames tend to look bulky because the frames have to be constructed in a way that will make up for aluminum's lack of strength. Many riders don't like the stiff feel of riding an aluminum bike.
For a long time, the best bike frames made use of carbon fiber. Carbon fiber mountain bikes are both lightweight and durable. Because of the expense, some carbon fiber frames are actually only partially made of carbon fiber. In many cases carbon fiber is used for the front fork of the mountain bike frame.
Competitive mountain bikers and serious mountain bikers generally prefer a titanium frame. Most people know that titanium is very strong. What many don't know is that this property allows a strong frame to be made that is very lightweight as well. However, the price is prohibitively high. So many serious mountain bikers stick to carbon fiber.
The Importance of Frame Size
Regardless of the type of use your mountain bike will be getting and the quality of the frame composition, if the frame isn't the right size for you then the bike won't be a good bike for you. Both the comfort of your rides and the control you have over your bike on varied terrain depend on how well your mountain bike frame fits you.
If you are used to riding street bikes, it is important for you to understand that mountain bikes fit differently. Mountain bike frames are smaller to keep you in better control of the bike. Generally your mountain bike frame will need to be 3” to 6” smaller than your street bike frame. You can test the height of your mountain bike by straddling it with the seat against your back. When you lift the front of the bike up until it touches your crotch, you should have the front wheel about 4” above the ground.
The Right Shape for Your Ride
Your mountain bike frame should be shaped according to the type of riding you do. A bike frame with steep angles is most ideal for hill riding, while a frame with relaxed angles is most ideal for stability while riding at higher speeds.