Electric bicycle - this is how the electric drive works. Here in Europe, but also in Japan, this type of drive is particularly common in pedelecs . This type of drive supports riders when pedaling, but it cannot fully power the bike.
The basic principle of the electric drive is the same for all types of electric bikes. The only difference is the control technology due to the application of different traffic regulations. Legal restrictions are most severe for Pedelecs. The electric drive on an electric bike can only work when you pedal. The pedal and the speed are registered by sensors.
What role does the traction battery play in electric drive?
A traction battery, often a removable battery (colloquially often just: "battery"), is a combination of several battery cells. This is the energy reserve of the drive and therefore the component that limits the range (connected to the hub with the motor mount).
The types of batteries used over the years (lead, nickel-cadmium (NiCd), nickel-metal hydride (NiMH) and lithium-ion batteries) have increased energy density, in that order. Increases by about half from type to type. However, the amount of energy stored in modern lithium-ion batteries (0.12–0.2 kWh/kg) is still significantly less than the energy density of liquid fuel (about 10 kWh/kg).
Lead-gel batteries are rarely used due to their low energy density. The sale of nickel-cadmium batteries for this purpose was banned in Germany in 2009 under the RoHS directives due to the environmental impact of the cadmium they contain, with some exceptions.
The charging time of the battery is between 1 and 16 hours, depending on the type and technology of charging, usually between 2 and 9 hours.
Most manufacturers currently use particularly lightweight lithium-ion batteries. They can be charged several hundred times (full charge cycles are taken into account). They can cause strong chemical reactions in the event of a short circuit or overheating.
These risks are practically eliminated with the help of modern battery management. Lithium-ion batteries deliver significantly less power at low temperatures and normally cannot tolerate frost.
In the near future, lithium polymer batteries with an even higher energy density will be available. There are also the first practical test models in which the battery has been replaced by a fuel cell and a hydrogen tank. This design offers the advantage of avoiding charging time and battery wear and additional capacity can be used on a longer tour.
Alternatively, there are lithium iron phosphate batteries, such as those in the Saxonette Beast 250, which are significantly more durable than the currently preferred lithium-ion batteries. Their use can reduce the operating costs caused by battery wear. However, they are not yet available in Germany except for Sachs Bikes.
How does the engine control system control the electric drive?
The motor control (the third part of the electric auxiliary drive of an electric bicycle besides the motor and battery) performs three different tasks:
- Motor operation (electronic switch in brushless motors), protection of motor and battery against overload and overheating, shutdown of the drive when the battery is discharged,
- The motor control offers convenient and easy use in everyday work, a user interface for the user (control, display of charging status, speed, distance, remaining range, selected support level) and protection against unauthorized use.
- The motor control complies with the legal restrictions - these can be: - Pedelec drive only assists when the driver is pedaling, does not allow the motor to operate above the permitted speed, does not allow the electric drive to work as the only drive (when starting or as support when pushing the bike).
Which electric motor is recommended for an electric folding bike?
If you want to buy an electric folding bike , you should pay attention to three things about the motor: the position of the motor, the power and the manufacturer. The motor power should be exactly 250 watts. There are two good reasons for this:
If the motor has more than 250 watts, you will need an operating permit, insurance and a driving license for your electric bike in Germany, as the bike is considered a moped or scooter. If the motor has less than 250 watts of power, you will have less acceleration and less fun with your electric folding bike.
Bosch, Samsung, Bafang, Shimano , Panasonic - there are many companies that produce motors for an electric folding bike . In principle, the driving pleasure does not depend on the manufacturer, because 250 watts is 250 watts. However, it is recommended to choose well-known producers. Since these companies cause fewer problems in the event of a complaint.
Even better than a large manufacturer is a large German manufacturer (for example Bosch). There are many instructions for these engines on the Internet, for example how to tune them.
Which motor positions have which advantages and disadvantages on the electric folding bike?
There are three positions on the electric bike where the motor can be attached. These are on the hub of the front or rear wheel and in the middle of the wheel.
Electric folding bike with rear wheel motor (rear wheel drive):
When using a rear-mounted e-bike, the motor is mounted in the middle of the rear wheel. The advantages are direct power transmission, dynamic handling, a quiet engine and the ability to recover energy.
In addition, the rear motor can also be installed later on many bicycles. In addition to the difficulty of removing the rear wheel, the biggest disadvantage of rear-wheel drive is the strong rear-wheel drive itself, as the center of gravity is far behind the rider.
Electric folding bike with front wheel motor (front wheel drive):
Buying an electric folding bike with a motor on the front wheel is not recommended. The only advantages are a low purchase price and the possibility of retrofitting the electric motor on many folding bikes. Otherwise, the front-wheel drive affects the steering behavior due to the high weight and subjects the fork to particularly high loads.
Mid-engine on a folding electric bike:
The drive mounted in the middle of the electric bike promises an even weight and ride distribution that is close to a conventional folding bike thanks to its central and lower center of gravity. Since the drive is also located near the battery, the cables cannot be damaged as easily.
The disadvantage of a "mid-engine" is that it is usually more expensive and cannot be retrofitted. In addition, the chain and possibly the gear wheel are subjected to particularly high loads.
What drive system is available for an electric fat bike?
The electric fat bike has been in fashion for a long time. Finally, the fat bikes seem to be making their mark in the electronic version. But what are the advantages of the electric fat bike and who would benefit from e-fat bikes ?
Like regular bikes with thick tires, E-Fat bikes are perfect for unpaved roads and off-roading. No matter what surface or what conditions - the tires ensure that you are virtually guaranteed not to sink in. But they are also the right choice in many other situations!
The fat electric bike combines the advantages of two excellent concepts. The weight of the thick tires and the increased rolling resistance of the E-Fat Bike are balanced out by the electric drive. This means that the grip advantage can be optimally used, especially on steep climbs.
When it comes to drives, most manufacturers rely on mid-engines from Bosch, Bafang, Shimano or Yamaha. As with most e-MTBs, they are located in the middle section because the center of gravity is better distributed and the efficiency is higher than with rear-wheel drive engines - their weight distribution and driving dynamics correspond to the area of application.
Since the electric fat bike is mainly used on uneven terrain, we recommend a special housing that protects the motor from impacts and dirt. The range depends on the battery power. If you go on longer tours or frequently require a higher level of support, you should buy an additional battery.
