Material of bicycle frame tubes 

The bicycle frame tubes have evolved from the early chromium-molybdenum steel to aluminum alloy, and then to composite materials such as carbon fiber, other scandium alloys, magnesium alloys, titanium alloys, etc. Moreover, new material formulations are continuously being developed in industry. Enhancing the design capabilities of the tube structure, innovating processing techniques, makes the frame lighter, stronger, more comfortable, and more streamlined. However, apart from the weight of the frame, factors such as tensile strength and elastic coefficient also need to be considered. Therefore, although the density is low, the strength is insufficient. 

The main materials used to manufacture bicycle frame tubes include steel, aluminum alloy, titanium alloy, magnesium alloy, scandium alloy, carbon fiber, etc. Scandium alloy and magnesium alloy are newly developed materials and are relatively less used. 

The following will introduce the characteristics of several types of bicycle frame tube materials: 

Chromium-molybdenum steel bicycle frame tubes 

When one or more of the above-mentioned elements are added to carbon steel, the resulting steel is called an alloy steel. If two elements, molybdenum (Mo) and chromium (Cr), are added, it can be called molybdenum-chromium alloy steel. The function of molybdenum: to continuously enhance the strength of the steel and prevent the occurrence of temper brittleness. The function of chromium: corrosion resistance, rust prevention, and prevention of oxidation at high temperatures. 

The function of the pumping pipe is to maintain the thin-edge thick-arch shape of the bridge, while keeping the strength unchanged, reducing the weight, and ensuring strong metal strength. 

Before the 1990s, the frame tubes of bicycles were made of chromium-molybdenum steel. They had good torsional and tensile properties, and the welding at high temperatures did not affect the material, and the price was low. However, they were heavy and prone to oxidation. In recent years, a new material has emerged, which overcomes its shortcomings and brings out its advantages. The chromium-molybdenum steel frame has once again attracted people's attention. 

Steel is a commonly used material for the frame of bicycles. Its main advantages are good rigidity for long-distance riding, good elasticity of the tube (for shock absorption), good connection and working performance of the tubes, convenient welding, no need for heat treatment, and relatively low cost and price. However, its disadvantage is that it is too heavy, and it is prone to rust during maintenance. The shape of the tubes is not easy to match with metal fatigue problems. Nevertheless, many alloy steels have achieved excellent results in terms of stiffness, elasticity coefficient, transferability, stability, etc. Even in the ointment, it is still very heavy. Chromium-molybdenum steel is a commonly used steel type, with high strength and easy pipe drawing processing. Molybdenum can increase the strength of the steel and prevent it from embrittlement; chromium can cause corrosion and rust of the steel, and prevent high-temperature oxidation. 

Carbon fiber bicycle frame tube 

Carbon fiber is a new type of material with high strength and light weight. Strictly speaking, it is a composite material, not composed of a single material. It also includes other resins, glass fibers, aluminum alloys, etc. They can be mixed or overlapped according to their properties. It is currently a relatively lightweight frame material. Carbon fiber tubes are made by weaving a few fiber threads into a carbon fiber fabric, and then layering and overlapping them through a horse shoe tube. 

The development of carbon fiber is not a metal, but rather as a composite material with a unique structure. Carbon fibers are woven into fabric, and after being pre-impregnated with resin, it can become a pre-impregnated fabric. Then, the pre-impregnated fabric is cut, layered, and inserted into a Chinese mold for heating and forming. According to actual needs, it can be made into various different-shaped frames. Its characteristics include light weight, good elasticity (good shock absorption), stable riding sensation, excellent long-distance tracking and continuous feeling, high comfort, and constantly changing processes. However, its surface hardness is not good. When an external force applied exceeds its breaking activity strength, it will cause the material to fracture.