Carbon fiber is becoming a popular component in bicycle frames, yielding light yet strong bikes. Traditionally made of aluminum, steel and titanium, desirable bike frames have the right blend of strength, stiffness and weight. Although carbon frames may be trendy, frames made of traditional metals should not be overlooked. Bike manufacturers can use a variety of processes to produce light, strong and responsive frames out of traditional metals as well as carbon fibers.
Aluminum Frames
Aluminum is a light metal that is malleable. Pure aluminum is soft but becomes strong when mixed, or alloyed, with other metals. It is one-third lighter than steel, however, aluminum is half as strong as steel; it dents, dings and collapses with less force. Aluminum frames are generally made with larger tubing diameters and thicker walls. This process yields frames of quite adequate stiffness, that are still lighter than comparable steel frames.
Steel Frames
Another traditional metal for bike frames is steel. Steel is an incredibly strong metal, and can withstand more pressure than aluminum. Although heavier, a steel bike frame's tubes can be made thinner to help reduce weight without compromising strength and stiffness. Steel frames are excellent choices for touring bikes or bikes that will be used to pull additional loads; steel's weight lends stability and durability to the frame.
Titanium Frames
Titanium is another metal used to make high quality bike frames. It is stronger than aluminum and lighter than steel, but is comparable in strength to steel. If you made a frame with titanium and another with steel, using the same tubing dimensions, the titanium frame would be lighter, but less stiff. It would not be as stable when riding, especially on long trips or when pulling a load. Similar to aluminum frame manufacturing, altering the size of the frame's tubes can improve a titanium frame; titanium tubing diameters are increased to improve stiffness and handling.
Carbon Frames
Carbon itself is a fiber, and as such is fundamentally different in regards to bike frame construction when compared with traditional metals. It has a more pronounced "grain" than metal frames, but can be arranged in patterns that make it incredibly strong. The frames can also be made in different ways -- in one piece with the carbon material wrapped in different directions for strength and lightness or tubes can be made more like ordinary alloy or steel frames and then joined.
Comparisons
Although there are significant differences in the strength, stiffness and weight of a given metal, manufacturers use different processes -- altering tube lengths and diameters -- to produce bikes that are both light and strong and that handle well on the road or mountain. If the frame is well-built, it will yield a high-quality ride. Carbon fibers provide a unique opportunity to be arranged in such a way as to mitigate areas of stress and strain, potentially improving the quality of your bike frame. However, carbon fiber technology is relatively new, and may not be "fully mature." While carbon fiber frames may be excellent for racing on the road and mountain, they have not yet proven to be fully reliable and durable for heavy duty touring. Therefore, unless you are a serious or elite cyclist, carbon fiber frames are not essential to your performance.
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