First of all, what is an e-bike?
In fact, what is commonly referred to as e-bike in China refers to electric-assisted bicycles, which originally originated in Japan and later developed and grew in Europe.
According to EU regulations, related products are usually divided into three main categories: Pedelec, S-Pedelec, and E-bike.
Pedelec stands for Pedal Electric Cycle.This bike model is usually only used when the person pedal actively, the motor will help the rider, so it is also called a semi-trampling electric bike, also known as the e-bike in the common sense of Chinese riders.
Using different booster modes, Pedelec’s pedal assist can meet the special requirements of different users, usually divided into gears according to the strength of the booster.
There are also brands that make gear distinctions according to application scenarios, such as flat roads, off-road, climbing, and downhill. Of course, the degree of assist will affect the range of motor aids and the energy consumption of the battery.
Pedelec’s power rating and speed limit vary from country to country. According to EU standards, Pedelec motors must not exceed 250W.
After reaching a speed of 25 km/h, the boost is automatically turned off, and if it falls below that speed, the boost is automatically turned on again.
Some Pedelec also have a push assist system, which can be activated by pushing a button when the rider is pushing, and then the bike will match the walking speed to move forward, making it easier to push.
S-Pedelec is a high-speed model of Pedelec, also known as a high-speed electric bike. It works in the same way as Pedelec. The difference is that the S-Pedelec has a higher power rating and speed limit.
Therefore, in Germany, the S-Pedelec has been classified as a light motorcycle under the traffic law, so this model requires compulsory insurance and a permit to use.
It is also necessary to wear a suitable protective helmet when riding, install reflectors and not occupy the bike path.
Under certain conditions, Pedelec can change the speed limit by brushing the program and become S-Pedelec. Of course, most private modifications will violate local national regulations, so please do not take the risk.
E-bike is the abbreviation for electric bike. The biggest difference between it and an assisted bicycle is that even without a pedal, the vehicle will be driven by the motor.
Some e-bikes can reach a maximum speed of 45 km/h by throttle or button start, so in Europe e-bikes belong to the category of light motorcycles, and you may need to buy insurance and a license.
In fact, e-bikes can also be used to refer to Pedelec and S-Pedelec models in everyday language, and this usage is particularly common in the field of sports bikes. Over time, the original attributes of the electric bike slowly faded away and gradually became what we now call the e-bike.
The working principle of e-bike system
No matter what brand of e-bike system it is to convert electrical energy into kinetic energy and apply it to the bike’s transmission system to make the ride easier and less laborious.
And we often say that the electric power system, in essence, mainly parts of e-bike contains sensors, controllers, motors.
When the electric power system is running, the sensor will detect the speed, pedaling frequency, torque and other data transmitted to the controller by calculating instructions to control the operation of the motor.
It is worth mentioning that most motors do not act directly on the drive train, the motor output power is high speed and low torque.
It needs to pass through the reduction system to amplify the torque, while making the output speed close to the pedaling frequency of human legs (mid-motor) or the speed of the wheel (hub motor).
Therefore, for a mid-drive motor e-bike, the motor power output shaft and the bicycle tooth plate shaft are structurally two shafts, linked in the middle by a speed reduction mechanism.
And we can classify the mid-mounted motor into coaxial motor (also called concentric shaft motor) and parallel shaft motor according to the difference in relative positions of these two shafts.The Shimano mid-motor transmission structure, the right side of the white pinion, is connected to the motor’s power output shaft, while the leftmost is connected to the disk shaft, the two axes a left and a right in a parallel position, the middle by a series of transmission gear connected, so this motor structure is called parallel shaft motor.
Coaxial motor, as the name implies, means that the tooth plate shaft and the motor’s power output shaft are on the same axis.
These motors are mostly external rotor motors, using the space between the inner ring and the sides of the motor station to place the reduction system, so the coaxial motor looks smaller and has a more compact internal structure.
However, in a limited space, it is not easy to achieve multi-stage reduction, while also taking into account torque, heat dissipation and ensuring the concentricity of the drive shaft.
Which is the best mid-motor and wheel of e-bike?
The current booster motor systems on the market can be broadly divided into two types: mid-motor and hub-motor.
Mid-motor means the motor whose drive motor is installed in the five-way position of the frame (divided into native integrated type and five-way external type), which is connected to the body and transmits power through a chain to the rear wheels.
A hub-motor is a motor with the drive motor mounted in the hub position of the car, which acts directly on the wheel. For sports models, the integrated mid-motor is undoubtedly the best choice.
First of all, the motor drive system is located in the five-way frame, which does not affect the overall weight balance of the car, and for full suspension models, the mid-motor reduces the underspring mass, and the feedback of the rear impact is therefore more natural and has an inherent advantage in off-road handling.
Second, the wheel is relatively easy to replace. If it is a hub-motor, it is difficult for riders to upgrade the wheel by themselves, while the mid-motor does not exist in this case, players can buy the DIY frame set by themselves, greatly increasing the playability.
At the same time, an excellent and efficient gearbox can also reduce transmission losses, greatly enhancing the range.Third, when riding off-road, the mid-motor suffers less impact than the hub-motor, so it is more favorable in terms of protection, thus reducing the risk of damage to the motor and lowering the failure rate.
For non-sports models, the choice of hub-motor does not require a major change to the traditional frame structure, coupled with the low cost, more easily accepted by the commuter class.
What is the size of the tooth plate of e-bike?
Often concerned about electric power products enthusiasts may notice that the same mid-motor e-bike, some discs are large, some discs are small, this is why?
In fact, although some motors are paired with a small gear plate, the actual pedaling is not slow, the mystery is that there is a mechanical speed-up device inside the motor. Use speed to compensate for torque.
That is, the crank pedal takes a turn, the disc actually turns two points a few turns, so a dozen small tooth disc is equivalent to more than 30 tooth disc pedaling effect.
Using RPM to compensate for torque, on the one hand, it can reduce the tension load of the chain, which is particularly important for the violent output of an e-bike.
On the other hand, the high speed of the tooth plate shaft reduces the pressure of the motor reduction mechanism in the limited space.
The size of the reduction mechanism, the running load, and the overall size of the motor will all be reduced.However, there are two sides to everything, high speed will intensify the wear of the small gear disc, and need to work on the disc material, and the designer also needs to solve the problem of chain and rear lower fork interference when the small disc is hitched to the small fly state.
The sensors currently used on the market can be divided into torque sensors, pedal frequency sensors, and speed sensors.
Torque sensors are used to measure the slight deformation of the metal surface after pedaling force, so as to obtain high precision torque values.
As the name implies, the pedal frequency sensor is used to measure the pedal frequency to determine the need for assistance.
Basically, the faster the pedal frequency, the harder the aid, the slower the pedal frequency, the weaker the aid. The speed sensor is the same, but this setting obviously can not match the real needs.
For example, when climbing or encountering headwinds, people’s pedaling frequency and speed becomes slower, while motor default riders do not need much help.
Therefore, e-bikes using pedaling frequency/speed sensors usually include pure electric mode.
However, this also deviates from the original purpose of electric power to some extent. Some brands also call it a speed sensor or magnetic ring sensor to hide it from the public and improve its appearance.
A reliable e-bike will usually use torque, pedaling frequency and speed sensors superimposed to determine the current riding status through comprehensive computing.
Controlling the program - the invisible hand of God
The same motor, the same e-bike, the manufacturer can make you feel a very different riding experience by brushing the program. This is not metaphysical.
As mentioned above, after the controller monitors torque, speed and pedaling signals, it will pass the signals to the controller, and the controller will calculate the output signal to guide the motor on how to produce power.
The controller’s algorithm is what we call the control program.
Some e-bike brands even open the program debugging port on the APP, allowing players to freely adjust the booster curve.
On the same bike, you can make it start fast at the beginning, cruise smoothly in the middle, and accelerate furiously at the end, or make it start smoothly, speed sensitively in the middle, and limit the speed smoothly at the end.
In today’s digital world, when hardware technology is developed to a certain level, software will become the key to the decisive difference in the motor.
Motor rated power
Usually we refer to the motor power rating as the rated output power of the motor. That is, in the ideal state , the long-term normal operation of the maximum output power, also known as the “maximum use of power”.
Note that the rated power of the motor is not equal to the peak power.
Many riders are used to using the rated power to measure the performance of the motor, which is strictly speaking not true, because it also involves the structural design of the motor, rated voltage, conversion efficiency, output torque and many other factors, even if the rated power of the same two motors, there are completely different riding experience.
Some countries and regions have mandatory regulations on the rated power of electric-assisted bicycles.
For example, the EU standard is that the rated power should not be higher than 250W, while in some parts of the United States, this standard will be relaxed to 750W, and in China, the new national standard stipulates that the rated power of electric vehicles and electric-assisted bicycles should not exceed 400W.
Many people are used to using mA to express battery capacity, but strictly speaking, this is the wrong expression.
MA is the unit of measurement of current, mAh is the correct unit of battery capacity, and some strict brands will also be marked with wh at the same time.
For example, if the battery voltage is 36V and the capacity is 13.6Ah, if converted to wh, that is 13.6*36=489.6, that is 489.6wh, about equal to 0.5 Kwh, which is half a degree of electricity.
Inside the battery pack is something:
Whether it is an external battery or a hidden battery in the frame, the “battery” that we see is actually just the shell of the battery pack. Open the shell, inside is a dense arrangement of cells and BMS.
The e-bike currently on the market usually uses 18650 lithium battery cells, which have a long life, high capacity per unit density and stable working performance.It should be noted that 18650 is the cell specification model (cell diameter 18mm, length 65mm).
Even if the same manufacturer produces different levels of 18650 cells, its capacity and durability are different, not to mention the gap between the international brand and the black workshop.
If a brand vaguely says “Tesla with the same battery cell,” then riders should keep an eye out for more.
Tips to improve the e-bike battery range
Endurance is one of the most important parameters for many riders when buying an e-bike. In fact, in the case of the same power, the use of some energy-saving tips can effectively improve the range.
Use the power-assist gears wisely to maintain a stable riding rhythm. Many riders like to add power-assist gear to the fiercest as soon as they get on the bike, and also pull frequently during long rides, and such operation is undoubtedly very high on power consumption.
If you want to ride farther, maintaining an even pedaling rhythm and just the right amount of power assistance is the most energy-efficient way to operate.
Don’t forget the mechanical gear. Many experienced riders make the mistake of ignoring mechanical shifting after having electric power, and climbing with a small 11T flywheel with 4-speed power.
Using mechanical gearing on long climbs can save nearly half of the electricity, reduce motor load and heat, and reduce damage to chains and discs.