What material is good for electric bike frame?
The electric bike frame is the soul of mountain bikes. The material of the selected frame differs for different purposes. Like long-distance riders and people who often cross-country, the choice of electric bike frame is different, so many riders don’t know what material is good for the frame of an electric mountain bike and don’t know how to choose electric bike frame kit .Here are 4 commonly used materials for downhill bicycles and their advantages and disadvantages.
1.Carbon fiber frame and features
In the past ten years, carbon fiber has been used as a high-tech material in bicycles. Strictly speaking, carbon fiber is not just carbon, but a mixture of carbon elements bonded and reinforced with epoxy resin after weaving. In the early days of carbon fiber, due to technical reasons, the epoxy resin used would even decompose in the sun. With the advancement of science and technology, the shortcomings of this excellent material have been gradually overcome. For example, the German K frame uses advanced 16K carbon fiber. The strength of this carbon fiber even exceeds that of steel, and it has a lifetime quality guarantee.
Generally speaking, carbon fiber as a material for electric bicycles has the following characteristics:
1.Extremely light weight: Carbon fiber road frames of about 1200 grams are already ubiquitous. Because 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 kilogram.
2.Good shock absorption performance. Carbon fiber can effectively absorb vibration and maintain good rigidity. This feature makes it a very good competition-level material.
3.Can make various shapes of mirror frames. Different from the manufacturing process of ordinary metal frame, carbon fiber frame is generally first made with a mold, then a carbon fiber sheet is placed on the mold, and finally fixed with epoxy resin. This manufacturing process can use aerodynamics to create a frame with minimal wind resistance.
The current problems with this material mainly include the following two points:
1.Complicated stress calculation. The carbon fiber frame is composed of carbon fiber, which is characterized by strong tensile strength but weak shear strength. During the processing, complex stress calculations (longitudinal stiffness and transverse stiffness) are required, and carbon fiber sheets are superimposed according to the calculation. Generally speaking, the impact resistance of carbon fiber is quite good, but the puncture resistance is very poor. In other words, it doesn’t matter if you shoot horizontally or vertically. You are afraid that you will encounter one or two sharp pebbles during the vertical and horizontal shooting. You cannot solve it by soldering.
2.The price is expensive. Compared with titanium alloy, the price of carbon fiber frame is lower. The top carbon fiber frame costs tens of thousands, while the price of Conago’s C40 and C50 is more than 20,000. Yuan. This is mainly because the carbon fiber frame manufacturing process requires a lot of manual work, and the scrap rate is very high, resulting in a substantial increase in costs.
2.Titanium frame and characteristics
Titanium is an emerging metal. This new material has very superior performance and is one of the best materials for making high-end spectacle frames.
1.Titanium alloy can make a lightweight and high-strength frame. 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 that of steel, so the titanium alloy frame of the same strength is much lighter than the steel frame.
2.Titanium alloy has good elasticity and is indispensable in absorbing riding vibration. The titanium alloy frame is very comfortable, and titanium is a memory metal. It has almost unlimited service life within its deformation range, which means that buying a titanium alloy frame is a once and for all method. (Laughs) Generally speaking, under professional use conditions, the service life of aluminum alloy frames is 2 years, steel frames are 8 years, and titanium frames can reach about 20 years.
3.Under normal conditions, titanium hardly corrodes. Titanium has advantages and disadvantages, and titanium alloys also have their inevitable disadvantages. The most troublesome thing at present is one word: Expensive! !
In terms of metal content, titanium is not actually a rare metal. However, the titanium element in the natural state generally exists in the form of titanium dioxide, and the extraction process is complicated, the technical requirements are high, the time is long, and the cost is high. The welding process is extremely difficult, because titanium has a strong affinity with oxygen, and immediately becomes titanium dioxide when it comes in contact with air. Titanium dioxide is hard and brittle, and the strength of this part will continue to decrease. Inert gas must be used with care. Generally speaking, Tig welding is: (Tig: short for tungsten, an inert gas) arc welding with tungsten electrodes and argon gas. The welding of titanium must be carried out in air. For these reasons, titanium frames are expensive. Generally speaking, the price of domestic cruise ships is about 3/2. 5 of Baotai titanium alloy frame. If it is AIRBONE or LITESPEED, the price of titanium frame is even more than tens of thousands. But if you consider the life of the titanium frame, the price will not feel outrageous.
3.Aluminum frame and features
1.Aluminum has poor metal fatigue.
The fatal weakness of aluminum bicycle frames is that when riding a bicycle made of this material, the more times you ride, the higher the number of stresses, and the strength will also change significantly. Recently, in order to reduce weight, many frames have used thin materials (thin to the limit). These are all made of aluminum alloy with no fatigue limit to make the frame, which is why the aluminum frame can only support 2-3 years under the strength of professional use.
2.Aluminum has no elasticity and cannot absorb the vibration of riding. The hard tailstock made of aluminum transmits most of the vibration directly to the rider’s body. This makes the aluminum frame quite bumpy and poor ride comfort. Due to these two shortcomings of aluminum, it is not suitable for general hard-tail frames. However, most of the XC off-road frames used in the competition are aluminum alloy. This is because the weight of aluminum can be very light, and great strength can also be obtained through heat treatment and tube drawing technology. Good (of course, the performance of the game will not consider the comfort of the player and the life of the product).
The full shock absorber has no such concerns. Because it has a completely independent shock absorption structure to absorb shocks, plus thicker and softer rubber and seat cushions, it completely offsets the lack of elasticity of aluminum. In addition, aluminum is lighter in weight, can be made with a larger cross-sectional area, and locally reinforced where strength is needed. Therefore, aluminum is a more mature and reliable material, which has advantages in making fully shock-absorbing frames.
4.Steel frame and characteristics
Steel is a material with a long history. From the most common civilian bicycles to high-end racing-grade vehicles, more or less steel is used. In addition to the improvement of smelting technology, steel also has advantages that other materials cannot replace:
1.Good processing performance. Chromium molybdenum steel is the oldest bicycle material and the longest time to study it. Therefore, its processing technology has developed to a fairly stable level.
2.High strength. It can be seen from the above 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 frame can be guaranteed.
3.It feels comfortable to ride. Steel is a metal with good elasticity. The frame made of steel can absorb vibrations generated during riding. Therefore, the steel frame is not as uncomfortable as the aluminum frame, and it is especially suitable for touring frame.
4.The metal fatigue strength of steel is much stronger than that of aluminum, so under the same conditions of use, the life of the steel frame will be much longer than that of the aluminum frame.
Of course, the steel frame also has its insurmountable shortcomings:
1.Weight: Today, when the equipment is extremely lightweight, the quality of steel 7.8/cm3 is prohibitive. Although light steel can be used, and the tube wall can be stretched very thin using tube drawing technology, it is still difficult to reduce the weight of the steel frame to below 1600 grams. Many aluminum frames weigh only about 1,400 grams. This is why steel frames are rarely seen in racing-grade frames.
2.Rust: Compared with other materials, steel is relatively easy to rust. Rust will greatly reduce the strength of steel and reduce its service life. Therefore, various measures must be taken to prevent the steel from rusting. So if it is not for the weight of the car, but also considering the durability of the frame, the steel frame is undoubtedly a good choice.
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