Guide: how to choose an electric bike on the example of Twitter - talking about frames
We are talking about cycle - materials from which they are made, and form factors.
Image: Gemma Evans / Unsplash
The frame material affects the price of the bike and its characteristics: appearance, weight, strength. The most commonly used are steel, aluminum, titanium and carbon.
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Steel frames began to use in the late XIX century . Bicycles with such frames are durable, but heavy. Gradually, steel began to crowd out other, more lightweight materials - aluminum and carbon. However, steel frames have not disappeared for good and are still to be found.
Most often manufacturers use two types of steel: carbon (Hi-Ten) and chrome-molybdenum alloy (Cro-Moly). Carbon steel is one of the simplest and cheapest materials. It contains no alloying additives and is found on entry-level bikes. Cro-Moly is composed of molybdenum, it gives the steel a fine-grained structure and increases strength.
Pros: The main advantage of the steel frame - strength. It is difficult to bend when hit or fall. Such a frame rarely breaks suddenly - cracks that appear for any reason develop gradually, letting themselves know with a creak. If a breakdown does occur, the steel structure is easy to repair. In some cases, bent pipes can be straightened and cracked seams can be digested. Steel is mainly made by entry-level bicycles and utilitarian vehicles, on which cargo can be transported.
Cons: As we have said, steel is heavier than other materials - the difference in weight can reach a kilogram. For example, the weight of a steel frame closely approaches two kilograms, while the carbon frame (which we will talk about later) may be lighter than 950 grams. Manufacturers use technologies designed to facilitate the steel frame of a bicycle, for example, batting (the design is assembled from pipes with variable geometry).
Another disadvantage of steel is corrosion susceptibility. If you don’t take care of such a frame, then on places of chips (where the paintwork is damaged) rust can appear rather quickly.
Aluminum frames - the most popular type in the modern industry. Two alloys are used - 6061 and 7005. The first contains impurities of copper and iron, which makes it more pliable. As a result, the production of the frame from 6061 is cheaper. The main alloying elements of the second alloy are zinc and magnesium, so it is more resistant to stresses and shocks.
Pros: The main advantages of aluminum - it is lighter than steel and better resists corrosion. Upon contact with oxygen, an oxide film appears on it that protects the metal from rust. However, if this protective layer is still broken (it can make a scratch and even salt, which is sprinkled on the road), the aluminum will begin to corrode.
Aluminum frames are relatively affordable. For example, the price of the Twitter VS7.0-ER100 electric bike with an aluminum frame is 54 thousand rubles. The Twitter TW-E9L Twitter carbon model will cost 150,000. Of course, the difference in attachments should be taken into account, but the overall trend is understandable.
Pictured : Twitter VS7.0-ER100
Cons: Aluminum "gets tired" over time, especially if there are dents on its surface. Some cyclists recommend regularly checking the state of the deformed aluminum frame and, if possible, not to delay its replacement. To increase the structural strength of the manufacturers, as in the case of steel, they use butting (double or triple), but this increases the cost of the frame.
Repairing an aluminum frame is also not an easy process. Due to the chemical characteristics of the material it is difficult to cook. Aluminum has a high coefficient of linear expansion , therefore, is strongly deformed when heated.
Such a frame is lighter than steel, but heavier than aluminum. By strength, it also turns out to be somewhere in the middle.
Pros: It is believed that the titanium frame is a frame for life. It is resistant to damage, practically does not wear out and does not corrode. Such frames are often left unpainted. Titan absorbs high-frequency vibrations well when driving on an uneven surface, so bicycles with a frame made of this material are considered more comfortable.
Cons: Production of titanium frame - a difficult process. Tools while cutting pipes wear out quickly (due to the hardness of the alloy), and special conditions are required for titanium melting. These features adversely affect the cost of the frame - it is twice as expensive as steel or aluminum.
The popularity (as a material for frames) carbon began to gain at the dawn of the 90s. Then professional cyclists began to use it, for obvious reasons (carbon frames were much lighter than steel frames at that time). In 1999, American road cyclist Lance Armstrong won the Tour de France on the bike Trek. It was the first time that a driver drove the entire route on a carbon bike.
Image: Markus Spiske / Unsplash
The high cost and sophisticated manufacturing methods prevented widespread carbon frames. Special fabrics from carbon fibers are laid in layers in forms, each time changing the angle of the weaving direction to give strength. Then the layers are sealed with epoxy resins. Initially, this process was absolutely not automated. Over time, technical processes have improved, but manual labor in the production of carbon frames is still in use .
Pros: The main advantage of carbon fiber - lightness. For comparison, Twitter has two carbon fiber electric bikes TW-E9L and E9W - their weight is 18 kilograms (taking into account the weight of the battery). While the weight of electric bikes with an aluminum frame reaches 20 kilograms .
Carbon is easy to give any shape, which opens up great opportunities for designers. Hence its popularity in the production of custom bikes. Offices such as Filament Bikes or Argonaut Cycles are creating custom-made carbon frames.
Cons: In addition to the high cost, among the shortcomings can be noted the fragility. If the integrity of carbon fiber is broken, then the frame can break at any time. And in most cases, broken carbon frames can not be repaired - they have to be changed entirely.
In the network you can find the site - Busted Carbon - the author of which posted photos of suddenly cracked carbon frames, sent by readers. There is a similar thread on Reddit .
The rigid frame has a rigid front fork and has no rear suspension. The first prototypes of modern bikes had just such a design. An example of a modern rigid bike can be the Airwheel R8 - its frame and front fork are made of high-strength aluminum tube.
Pictured : Airwheel R8
Pros: Low weight - a steel rigid fork weighs one and a half kilograms, aluminum approximately one kilogram, carbon weight and even less. The weight of the fork with depreciation approaches two kilograms.
Cons: Strong vibration of the steering wheel - at high speed if hit in pits or potholes there is a chance to lose control of the bike. Experts say that you can increase the comfort of driving by installing a carbon steering wheel. It will dampen vibrations. Also help a thick tire, 2.3 inches wide.
This is a bike with a solid frame, but having a front suspension. Perhaps the most common type of bike today.
Pros: Cushioned plug softens small shocks, it is more comfortable to drive with it. At the same time, the frame of the hardtail type still has a rather simple construction, which increases reliability.
Cons: Although this type of frame is adapted to cross-country driving, the ride can be tough. We tested the Twitter TW-E9L electric bike with a hardtail in off-road conditions and even had a small crash test .
The bike showed its best. However, to ride a hardtail bike along a “cross-path” is necessary for the most part standing - the absence of a rear shock absorber affects.
Bicycles with two shock absorbers - front and rear - are designed to overcome the stony slopes and steep descents. Such bikes are used by professional athletes in downhill competitions . However, riding around the city on such a bike also has its advantages.
Pros: Depreciation of both wheels completely eliminates small shocks, while large ones soften significantly. For this reason, it becomes comfortable to ride on any surface (including asphalt).
Cons: A strong buildup from pedaling, which takes away most of the muscular energy - it becomes harder to ride.
The second problem is the weight of the bike. Dvuhpodvesny aluminum e-bike weighing 20 kilograms is quite normal. For bicycles without an electric motor, this figure is slightly less - there are models weighing 18 or 19 kilograms.
Next time we will continue to talk about the components of electric bicycles: types of engines, batteries, pedals and body kits.
Twitter Bicycle Reviews:
Image: Gemma Evans / Unsplash
Material
The frame material affects the price of the bike and its characteristics: appearance, weight, strength. The most commonly used are steel, aluminum, titanium and carbon.
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Steel
Steel frames began to use in the late XIX century . Bicycles with such frames are durable, but heavy. Gradually, steel began to crowd out other, more lightweight materials - aluminum and carbon. However, steel frames have not disappeared for good and are still to be found.
Most often manufacturers use two types of steel: carbon (Hi-Ten) and chrome-molybdenum alloy (Cro-Moly). Carbon steel is one of the simplest and cheapest materials. It contains no alloying additives and is found on entry-level bikes. Cro-Moly is composed of molybdenum, it gives the steel a fine-grained structure and increases strength.
Pros: The main advantage of the steel frame - strength. It is difficult to bend when hit or fall. Such a frame rarely breaks suddenly - cracks that appear for any reason develop gradually, letting themselves know with a creak. If a breakdown does occur, the steel structure is easy to repair. In some cases, bent pipes can be straightened and cracked seams can be digested. Steel is mainly made by entry-level bicycles and utilitarian vehicles, on which cargo can be transported.
Cons: As we have said, steel is heavier than other materials - the difference in weight can reach a kilogram. For example, the weight of a steel frame closely approaches two kilograms, while the carbon frame (which we will talk about later) may be lighter than 950 grams. Manufacturers use technologies designed to facilitate the steel frame of a bicycle, for example, batting (the design is assembled from pipes with variable geometry).
It is interesting that not so long ago attempts were made to return the steel frames to the professional arena. The English Madison-Genesis team — last year’s winner of the UK National Road Cycling Championship — used Volare steel bikes a few years ago during the competition.
However, the steel frame still lost in weight to structures made of other materials. In the end, the team returned to the carbon.
Another disadvantage of steel is corrosion susceptibility. If you don’t take care of such a frame, then on places of chips (where the paintwork is damaged) rust can appear rather quickly.
Aluminum alloys
Aluminum frames - the most popular type in the modern industry. Two alloys are used - 6061 and 7005. The first contains impurities of copper and iron, which makes it more pliable. As a result, the production of the frame from 6061 is cheaper. The main alloying elements of the second alloy are zinc and magnesium, so it is more resistant to stresses and shocks.
Western aluminum bicyclists called early aluminum frames “wadded” (noodly). They were built from pipes of the same diameter as steel. The change in the stiffness of the material was not taken into account, so the frames were bent and “played” while driving.
Modern aluminum bikes have large pipes - the difference compared to steel can reach 20–30%.
Pros: The main advantages of aluminum - it is lighter than steel and better resists corrosion. Upon contact with oxygen, an oxide film appears on it that protects the metal from rust. However, if this protective layer is still broken (it can make a scratch and even salt, which is sprinkled on the road), the aluminum will begin to corrode.
Aluminum frames are relatively affordable. For example, the price of the Twitter VS7.0-ER100 electric bike with an aluminum frame is 54 thousand rubles. The Twitter TW-E9L Twitter carbon model will cost 150,000. Of course, the difference in attachments should be taken into account, but the overall trend is understandable.
Pictured : Twitter VS7.0-ER100
Cons: Aluminum "gets tired" over time, especially if there are dents on its surface. Some cyclists recommend regularly checking the state of the deformed aluminum frame and, if possible, not to delay its replacement. To increase the structural strength of the manufacturers, as in the case of steel, they use butting (double or triple), but this increases the cost of the frame.
Repairing an aluminum frame is also not an easy process. Due to the chemical characteristics of the material it is difficult to cook. Aluminum has a high coefficient of linear expansion , therefore, is strongly deformed when heated.
Titanium alloys
Such a frame is lighter than steel, but heavier than aluminum. By strength, it also turns out to be somewhere in the middle.
Pros: It is believed that the titanium frame is a frame for life. It is resistant to damage, practically does not wear out and does not corrode. Such frames are often left unpainted. Titan absorbs high-frequency vibrations well when driving on an uneven surface, so bicycles with a frame made of this material are considered more comfortable.
Cons: Production of titanium frame - a difficult process. Tools while cutting pipes wear out quickly (due to the hardness of the alloy), and special conditions are required for titanium melting. These features adversely affect the cost of the frame - it is twice as expensive as steel or aluminum.
Carbon
The popularity (as a material for frames) carbon began to gain at the dawn of the 90s. Then professional cyclists began to use it, for obvious reasons (carbon frames were much lighter than steel frames at that time). In 1999, American road cyclist Lance Armstrong won the Tour de France on the bike Trek. It was the first time that a driver drove the entire route on a carbon bike.
Image: Markus Spiske / Unsplash
The high cost and sophisticated manufacturing methods prevented widespread carbon frames. Special fabrics from carbon fibers are laid in layers in forms, each time changing the angle of the weaving direction to give strength. Then the layers are sealed with epoxy resins. Initially, this process was absolutely not automated. Over time, technical processes have improved, but manual labor in the production of carbon frames is still in use .
Pros: The main advantage of carbon fiber - lightness. For comparison, Twitter has two carbon fiber electric bikes TW-E9L and E9W - their weight is 18 kilograms (taking into account the weight of the battery). While the weight of electric bikes with an aluminum frame reaches 20 kilograms .
Carbon is easy to give any shape, which opens up great opportunities for designers. Hence its popularity in the production of custom bikes. Offices such as Filament Bikes or Argonaut Cycles are creating custom-made carbon frames.
Cons: In addition to the high cost, among the shortcomings can be noted the fragility. If the integrity of carbon fiber is broken, then the frame can break at any time. And in most cases, broken carbon frames can not be repaired - they have to be changed entirely.
In the network you can find the site - Busted Carbon - the author of which posted photos of suddenly cracked carbon frames, sent by readers. There is a similar thread on Reddit .
Form factor
Rigid
The rigid frame has a rigid front fork and has no rear suspension. The first prototypes of modern bikes had just such a design. An example of a modern rigid bike can be the Airwheel R8 - its frame and front fork are made of high-strength aluminum tube.
Pictured : Airwheel R8
Pros: Low weight - a steel rigid fork weighs one and a half kilograms, aluminum approximately one kilogram, carbon weight and even less. The weight of the fork with depreciation approaches two kilograms.
With a rigid fork, it is easier to drive, since the energy from pedaling goes straight into the wheels (not expended on cushioning). Serving such forks is also not necessary: ​​they have nothing to lubricate and clean. Plus, the rigid design has no moving components, which reduces the risk of breakage.
Cons: Strong vibration of the steering wheel - at high speed if hit in pits or potholes there is a chance to lose control of the bike. Experts say that you can increase the comfort of driving by installing a carbon steering wheel. It will dampen vibrations. Also help a thick tire, 2.3 inches wide.
Hardtail
This is a bike with a solid frame, but having a front suspension. Perhaps the most common type of bike today.
Pros: Cushioned plug softens small shocks, it is more comfortable to drive with it. At the same time, the frame of the hardtail type still has a rather simple construction, which increases reliability.
Cons: Although this type of frame is adapted to cross-country driving, the ride can be tough. We tested the Twitter TW-E9L electric bike with a hardtail in off-road conditions and even had a small crash test .
The bike showed its best. However, to ride a hardtail bike along a “cross-path” is necessary for the most part standing - the absence of a rear shock absorber affects.
Full suspension
Bicycles with two shock absorbers - front and rear - are designed to overcome the stony slopes and steep descents. Such bikes are used by professional athletes in downhill competitions . However, riding around the city on such a bike also has its advantages.
Pros: Depreciation of both wheels completely eliminates small shocks, while large ones soften significantly. For this reason, it becomes comfortable to ride on any surface (including asphalt).
Cons: A strong buildup from pedaling, which takes away most of the muscular energy - it becomes harder to ride.
There are systems that block the shock absorbers until they become necessary. The inertia valve responds to impact and unlocks the suspension.
As soon as the road becomes smooth again, the shock absorbers are blocked. But such solutions are not cheap and require regular maintenance. Therefore, they are mainly used by athletes.
The second problem is the weight of the bike. Dvuhpodvesny aluminum e-bike weighing 20 kilograms is quite normal. For bicycles without an electric motor, this figure is slightly less - there are models weighing 18 or 19 kilograms.
Next time we will continue to talk about the components of electric bicycles: types of engines, batteries, pedals and body kits.
Twitter Bicycle Reviews:
Source: https://habr.com/ru/post/455294/
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