Frames

The main component of a bicycle is the bicycle frame. The construction and materials used in the frame are the number-one factor in determining how the bicycle will feel and ride. Thus, knowing about the different bike frames can help you determine which bike is right for you.

The Diamond Bike Frame

The most common frame design is called the Diamond Frame. This type of frame consists of two paired triangles onto which all the other bicycle components may be attached.

The two triangles of the Diamond Frame are the main triangle and the rear triangle. The main triangle consists of the following components:

• The down tube is the long, angled tube connecting the head tube and the crank.
• The head tube is the short vertical tube that connects the handlebars and the forks.
• The seat tube is the vertical tube connecting the seat and the crank.
• The top tube is the long horizontal tube between the handlebars and seat.

The rear triangle consists of the seat tube, chain stays, and seat stays. The chain stays are the paired tubes running from the crank to the rear wheel. The two tubes connecting the seat to the rear wheel are the seat stays.

Bicycle Frame Material Characteristics

When talking about bicycle frame materials, people general use three terms:

• Stiffness refers to the "give" of a material. Stiffness has the greatest effect on the riding feel of a bicycle frame.
• Strength refers to the ability of a material to withstand crashes and time while maintaining its shape and durability.
• Weight refers to how heavy the material is.

Bicycle Frame Materials

The most common materials used in bicycle frame construction are:

• Aluminum alloy: Aluminum alloy bike frames are lighter than steel but aren't as strong or as stiff. Frame manufacturers make up for the decrease in strength and stiffness by increasing the diameter of the tubing used in frame construction.Aluminum alloy frames are good for mountain bikes because they have good durability while being lighter than a comparable steel frame.
• Carbon fiber: Carbon fiber is the only non-metal material used for bicycle frames. The composite properties of the material allow for good strength and stiffness at a very low weight. Carbon fiber can also be formed into any shape, eliminating the need for lugged joints.The downfalls of carbon fiber are it's vulnerability to impact and fatigue failure. Carbon fiber bicycle frames are ideal for time-trial racing and triathlon bicycles.
• Steel: The most common material used for bicycle frames is steel. Steel is a strong, stiff material that is cheap and easy to use. Steel frames are made using cylindrical tubes that are joined together.Steel bicycle frames are very good for stiffness and durability. A drawback of steel is its weight, as it is the densest of frame materials. These properties make steel a good choice for road bikes but a bad choice for racing or mountain bikes.
• Titanium: Titanium is the most expensive metal used in bicycle frames. A titanium frame has comparable strength to a steel bicycle frame but is significantly lighter. It is also about half as stiff as steel, so it does not require oversized tubing.The weight and strength of titanium bicycle frames make them ideal for time-trial racing bikes and triathlon bicycles.