What Material Is Good For Electric Bike Frame?
The frame is the soul of a mountain bike. The material of the selected frame will be different for different uses. Like the long-distance riders and the often off-road people, the choice of the frame is different, so many riders do not know the electric mountain bike What material is good for the frame, here we will introduce 4 kinds of materials commonly used in downhill bicycles and their advantages and disadvantages.
1.Carbon fiber frame and characteristics
Carbon fiber has been used on bicycles as a high-tech material for the last ten years. Strictly speaking, carbon fiber is not just carbon, but a mixture of carbon elements bonded and reinforced with epoxy resin after weaving. Early carbon fibers, due to technical reasons, used epoxy resins that even decomposed in sunlight. With the advancement of technology, the shortcomings of this excellent material are gradually overcome. For example, the K frame in Germany uses advanced 16K carbon fiber. The strength of this carbon fiber is even more than that of steel, and it has a quality guarantee for life.
Generally speaking, carbon fiber has the following characteristics as a electric bicycle material:
1. Extremely light weight: Carbon fiber road frames of about 1200 grams have been everywhere. 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-grade material.
3. It can make frames of various shapes. Different from the manufacturing process of ordinary metal frames, carbon fiber frames are generally made of molds first, then carbon fiber sheets are placed on the molds, and finally epoxy resin is used for fixing. This manufacturing process can use aerodynamics to make a frame with minimal wind resistance.
The current problems with this material are mainly the following two points:
1. Complex stress calculations. 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 lateral rigidity) are required during processing, and the carbon fiber sheets are superposed according to the calculation. Generally speaking, the impact resistance of carbon fiber is quite good, but the puncture resistance is very poor. That is to say, it doesn't matter if you shoot horizontally and vertically. You are afraid that you will encounter a sharp pebble or two during the process of shooting vertically and horizontally. You can't solve it by welding.
2. The price is expensive. Compared with titanium alloy, the price of carbon fiber frame is inferior. The price of top carbon fiber frame is tens of thousands, while the price of C40 and C50 of Conago is even more than 20,000. yuan. This is mainly because the manufacturing process of carbon fiber frames requires a lot of manual work, and the scrap rate is very high, causing a large increase in costs.
2.Titanium frame and characteristics
Titanium is an emerging metal. This new material has very superior properties and is one of the best materials for making top-grade frames.
1. Titanium alloy can make a light weight and strong frame. As can be seen from the table above, the strength of titanium is similar to that of steel, but the weight is only a little more than half of steel, so a titanium alloy frame with the same strength 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 memory metal. It has almost unlimited service life in its deformation range, which means that buying a titanium alloy frame is a kind of Once and for all approach. (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.
There are advantages and disadvantages to titanium, 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, the titanium element in the natural state generally exists in the form of titanium dioxide, the refining process is complicated, the technical requirements are high, and it takes time and therefore the cost is high. It is extremely difficult to perform the welding process, because titanium has a strong affinity with oxygen, and immediately becomes titanium dioxide upon contact with the air, and titanium dioxide is hard and brittle, and the strength of this part will continue to decrease. Care must be taken with inert gas. Generally speaking, Tig welding is: (Tig: abbreviation for tungsten, an inert gas) arc welding with a tungsten electrode and argon gas. Welding of titanium must be performed in the air. For these reasons, titanium frames are expensive. Generally, the price of domestically-made cruise ships and Baotai's titanium alloy frame of 3/2. 5 is about 3,000 yuan, and if it is AIRBONE or LITESPEED, the price of titanium frame is even tens of thousands. But if you consider the life of the titanium frame, this price will not feel so outrageous.
3.Aluminum frame and characteristics
1. Metal fatigue of aluminum is very poor.
The Achilles heel of bicycle racks made of aluminum is that when riding a bicycle made of this material, the more times you ride, the higher the number of times of stress, and the strength also causes significant changes. Recently, in order to reduce weight, many frames are made of thin materials (thinness has reached a limit). These are all made of aluminum alloy without fatigue limit to make the frame, which is why the aluminum frame can only support 2-3 years under the professional use intensity.
2. Aluminum is not elastic and cannot absorb the vibration of riding.
The hard tail frame made of aluminum transmits most of the vibration directly to the rider's body. This makes the aluminum frame quite bumpy, and the riding comfort is poor.
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 competition are aluminum alloys. This is because the weight of aluminum can be very light, and great strength can also be obtained through heat treatment and pipe drawing technology. Good (of course, the performance of the competition will not take into account the comfort level of the players and the service life of the product).
Full shock absorbers have no such concerns. Because it has a completely independent shock-absorbing structure for absorbing vibrations, plus thicker and softer rubber and seat cushions, the disadvantage of aluminum without elasticity is completely neutralized. In addition, aluminum's lighter weight makes it possible to make a larger cross-sectional area, and local reinforcement where needed strength. Therefore, aluminum is a more mature and reliable material, and it has an advantage when making full 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, steel is more or less used. In addition to the improvement of smelting technology, steel also has advantages that other materials cannot replace:
1. Good processing performance. Chrome-molybdenum steel is the oldest bicycle material, and it has been the longest time to research it. Therefore, 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 assured.
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 during riding. Therefore, the steel frame is not as uncomfortable as the aluminum frame, and is particularly suitable for making a travel frame.
4. The metal fatigue 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, steel frames also have their insurmountable disadvantages:
1. Weight: In today's extreme pursuit of lightweight equipment, the quality of steel 7.8 / cm3 makes everyone discourage him. Although it is possible to use lightweight steel, and the pipe wall is drawn very thin by using the pipe drawing technology, it is still difficult to reduce the weight of the steel frame to less than 1600 grams. Many aluminum frames weigh only about 1,400 grams. This is why steel frames are rarely seen in race-grade frames.
2. Rust: Compared with other materials, steel is relatively easy to rust. Rust can 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 racing weight, and considering the durability of the frame, the steel frame is undoubtedly a good choice.