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The frame is the soul of a mountain bike. The material of the frame will be different for different purposes. For example, people who often ride long distances and people who often cross-country choose different frames, so many riders don’t know about mountain bikes. What material is good for the frame, here we will introduce the 4 materials commonly used in mountain bikes and their advantages and disadvantages.

1. Carbon fiber frame and features

Carbon fiber has been used in bicycles as a high-tech material for the last ten years. Strictly speaking, carbon fiber is not a simple carbon element, but a mixture of carbon elements that are woven and reinforced with epoxy resin. For technical reasons, the early carbon fibers used epoxy resins that even decomposed in sunlight. With the advancement of technology, the shortcomings of this excellent material are gradually being overcome. For example, the German K frame uses high-grade 16K carbon fiber, which is even stronger than steel and has a quality promise of lifetime warranty.

Generally speaking, carbon fiber as a bicycle material has the following characteristics:

1. Extremely light weight: carbon fiber road frames of about 1200 grams have been seen everywhere. Since the mass of carbon is only 1.6 grams per cubic centimeter, it is no longer a dream to make a frame of about 1 kg.

2. Good shock absorption performance. Carbon fiber can effectively absorb shock and maintain good rigidity. This feature makes it a great competition-grade material.

3. Frames of various shapes can be made. Different from the manufacturing process of general metal frames, carbon fiber frames are generally made of molds first, then put carbon fiber sheets on the molds, and finally cement them with epoxy resin. This manufacturing process can use aerodynamics to create a frame with minimal wind resistance.

The current shortcomings of this material are mainly the following two points:

1. Complex stress calculation. The carbon fiber frame is composed of carbon fiber, which is characterized by strong tensile strength, but weak shear strength. Complex stress calculations (longitudinal rigidity and transverse rigidity) are required during processing, and carbon fiber sheets are overlapped and formed according to the calculation. Generally speaking, the impact resistance of carbon fiber surface is quite good, but the puncture resistance is very poor. That is to say, it doesn't matter if you fall horizontally and vertically, but you are afraid that you will encounter one or two sharp pebbles during the horizontal falling and vertical shooting.

2. The price is expensive. Compared with titanium alloy, the price of carbon fiber frame is even more expensive. The price of the top carbon fiber frame is tens of thousands, and the price of Konago's C40 and C50 is even more than 20,000. Yuan. This is mainly because the production process of carbon fiber frames requires a lot of manual work, and the scrap rate is very high, resulting in a large increase in cost.

2. Titanium frame and features

Titanium is an emerging metal, this new material has very superior properties and is one of the best materials for making top frames.

1. Titanium alloys can make frames with light weight and high strength. As can be seen from the above table, the strength of titanium is similar to that of steel, but the weight is only a little more than half of steel, so titanium alloy frames with the same strength Will be much lighter than a steel frame.

2. Titanium alloy has very good elasticity, which makes it indispensable in absorbing riding vibration. The frame made of titanium alloy has very good comfort, and titanium is a metal with memory, which has almost unlimited service life within its own deformation range, that is to say, buying a titanium alloy frame is a kind of A once-and-for-all approach. (laughs) Generally speaking, under professional use conditions, the service life of an aluminum alloy frame is 2 years, a steel frame is 8 years, and a titanium frame can reach about 20 years.

3. Under normal conditions, titanium will hardly corrode.

There are advantages and disadvantages, and titanium alloys also have their inevitable disadvantages. At present, the most headache is one word: expensive!!

In terms of metal content, titanium is actually not a rare metal. However, titanium in its natural state generally exists in the form of titanium dioxide. The refining and processing process is complicated, the technical requirements are high, and the time and cost are high. In addition, the welding process is extremely difficult, because the affinity of titanium and oxygen is very strong, and it will become titanium dioxide immediately after contact with air, and titanium dioxide is hard and brittle, and the strength of this part will continue to decline. Welding must be done carefully with inert gas. The so-called Tig welding is: (Tig: abbreviation for tungsten, inert gas) arc welding with tungsten electrode and argon gas. Welding of titanium must be carried out under the isolation of air. Titanium frames are expensive for these reasons. Generally, the price of the domestically produced air wheel and the 3/2.5 titanium alloy frame of Baoti is about 3,000 yuan, and the price of the titanium frame like AIRBONE or LITESPEED is even tens of thousands. But if you consider the life of the titanium frame, the price will not feel so outrageous.

3. Aluminum frame and features

1. The metal fatigue resistance of aluminum is very poor.

The Achilles heel of a bicycle frame made of aluminum is that when riding a bicycle made of this material, the more times you ride it, the higher the number of times the stress occurs, and the strength changes significantly. Recently, in order to achieve light weight, many frames are made of thin materials (the degree of thinness has reached its limit). These are made of aluminum alloys with no fatigue limit, which is why an aluminum frame can only support 2-3 years under professional use strength.

2. Aluminum has no elasticity and cannot absorb the vibration of riding.

A hardtail frame made of aluminum transmits most of the shock directly to the rider's body. This makes the aluminum frame quite bumpy to ride, and ride comfort is poor.

Because of these two deficiencies of aluminum, it is not suitable for general hardtail frames. However, most of the XC off-road frames used in competition use aluminum alloys. This is because the weight of aluminum can be very light, and the strength can also be obtained through heat treatment and butting technology, which makes the aluminum frame very competitive. Good (race performance of course does not take into account the comfort of the players and the service life of the product).

The full shock absorber car does not have these scruples. The lack of elasticity of aluminum is completely neutralized by having a completely independent shock-absorbing structure for absorbing shocks, plus a thicker and softer rubber and seat cushion. In addition, the lighter mass of aluminum allows for larger cross-section areas and local reinforcement where strength is required. Therefore, aluminum is a more mature and reliable material, and it has an advantage when making a full-shock frame.

4. Steel frame and features

Steel is a material with a long history, from the most common civilian bicycles to high-end competition-level vehicles, more or less steel is used. In addition to the improvement of smelting technology, steel also has advantages that cannot be replaced by other materials:

1. Good processing performance, chrome-molybdenum steel is the oldest bicycle material, and its research time is also the longest, so its processing technology has developed to a fairly stable level.

2. High strength. From the above, we can see that the strength of steel under the same volume is much greater than that of aluminum alloy and titanium alloy, so the strength of qualified steel frames can be reassuring.

3. The riding feeling is comfortable. Steel is a kind of metal with good elasticity. The frame made of steel can absorb the vibration caused by the riding process. Therefore, the steel frame will not feel as uncomfortable as the aluminum frame, and it is especially suitable for use as a touring frame.

4. The metal fatigue of steel is much stronger than that of aluminum, so under the same conditions of use, the life of steel frame will be much longer than that of aluminum frame.

Of course, the steel frame also has its insurmountable shortcomings:

1. Weight: In today's extreme pursuit of lightweight equipment, the quality of steel 7.8/cubic centimeter makes everyone shy away from him. Although it is possible to use lightweight steel and use the pipe drawing technique to draw extremely thin walls, it is still difficult to reduce the weight of the steel frame to less than 1600 grams. And many aluminum frames weigh only about 1400 grams. That's why steel frames are rarely seen in race-level frames.

2. Rust: Compared with other materials, steel is easier to rust. Rusting will greatly reduce the strength of the steel and reduce the service life. Therefore, various measures must be taken to prevent the steel from rusting.

Therefore, if you are not pursuing the weight of the competition level and considering the durability of the frame, the steel frame is undoubtedly a good choice.

However, it should be pointed out that at present, good steel frames in China are harder to find than good aluminum frames. First of all, a good frame is not cheap. The high-grade steel frame of the Renault 853 series costs several thousand, while the steel frame of the Italian Konago costs tens of thousands. In addition, due to people's preference for aluminum frames, steel frames are difficult to sell. With the collapse of the domestic bicycle giant, China Bicycle Company, good steel frames have almost disappeared in China, which is really a pity!