If you are thinking about buying a mountain electric bike or a road electric bike, or you simply want to understand how they work, what follows will interest you. These bikes have gained popularity in recent years, and now is the perfect time to clarify some key aspects.
Essentially, an electric bicycle keeps the same structure as a conventional bike, but incorporates components that allow you to go further with less effort. It's important to note that we are talking about pedal-assist bikes, which means that the motor only activates when we put pressure on the pedals. If this were not the case, we would be talking about motorcycles.
And yes, riding an electric bike is still exercise, only with an extra boost to reduce effort when needed. The assistance, according to regulations in Spain and the EU, is maintained up to 25 km/h, at which point the motor stops providing power.
But what makes this technology possible? A mountain electric bike or a road electric bike has five essential components: the motor, the battery, the sensors, the controller, and the display. Next, we explain the function of each one and how they affect the pedaling experience.
The motor of an electric bike
The motor of an electric bike can be located in different parts of the frame and affects your machine's behavior to some extent, with its benefits and drawbacks. The motor can be mounted in three places:
- In the front wheel hub.
- In the rear hub.
- In the bottom bracket, in the center of the bike.
Let's see what is particular about each location. The front wheel motor is usually the most affordable in price. But this is relative. We see it a lot in folding urban bikes, like Brompton and others, which are not really that cheap. But to what interests us: they provide plenty of power to get around the city with ease and take up little space. On the other hand, it is necessary to control their thrust on slippery terrain. As you know, losing control of the front wheel means an almost certain fall. Something similar can be said about rear hub motors . They are usually a bit more expensive. They transmit power to the drivetrain more directly than the front hub. In addition, due to their location, they make the bike feel more maneuverable. The risk of the front wheel slipping is lower, which has an impact on our safety. In general, hub motors are ideal for intensive use, as their mechanism is relatively simple and maintenance is not costly. They are the ideal solution for urban mobility, for example, although their installation is also common on other types of bicycles. Finally, we can have a bike with a mid-drive motor, which is located on the bottom bracket axle. This is the one that offers the highest performance, also influencing greater autonomy compared to other motors. It also provides more stability. The center of gravity is lowered and the weight on the bike is perfectly distributed. This is the motor that is standard on high-performance bikes, both mountain and road. In short, it is the motor that allows for a more natural pedaling experience because it responds instantly to the movement of the cranks. 
You also have to take certain drawbacks into account. These are the most expensive motors; partly because they affect the overall design of the bicycle. In addition, they are heavier than hub motors, take up more space, and consume more energy. On the other hand, the stresses they cause tend to affect the drivetrain components (especially the chain and sprockets) to a greater extent. In all cases, the mission of the motor is to absorb the energy provided by the battery and transform it into power that assists our pedaling.
The maximum torque
If we talk about the motor of an electric bike, it is essential to mention a very important concept: torque or maximum torque. Without going into detail, it is the acceleration with which your electric bike takes off. Let's say it represents the force your foot exerts on the pedal. Its unit of measurement is the Newton meter (Nm). Normally, this value ranges between 50 and 120 Nm, being higher in the case of mountain bikes intended for intensive use. The need to overcome obstacles and steep slopes determines these numbers. Unlike what happens with power, current regulations do not set limits on torque. However, you should keep in mind that a high maximum torque will decisively affect battery life. For this reason, you should be clear about the terrain you will be riding your bike on so you don’t waste energy or extra money on your purchase.
The battery of an electric bike
The choice of battery is crucial, as it affects the weight, range, and performance of our electric bike. It can be located in different places, depending on the size and type of frame. The trend is for batteries to become increasingly compact and better integrated into the overall design of the bicycle. Let's admit that a battery, by itself, is not a very aesthetic component.The power and speed of an electric bike depend on the motor watts (W). The capacity , for its part, is expressed in watt-hours (Wh) and is the result of multiplying the system voltage by the battery's amperes. Complicated? To understand this relationship, let's look at an example. In Spain, by law, the power of an electric bike motor is limited to 250W. Imagine we have a battery with a capacity of 500 Wh. This means it could provide energy at maximum power for two hours (2 x 250Wh = 500Wh). You can find all these values in the technical specifications of each battery. In theory, the greater the energy capacity of a battery, the greater its range. You’ll be able to travel more kilometers without needing to recharge it. But as mentioned, this is only in theory. 
The range of a battery also depends on many other factors. The strength of the wind, the temperature, the terrain conditions, the combined weight of cyclist and bicycle, our pedaling style, the level of demand we place on the battery, the tire pressure…
The sensors of an electric bike
The pedal sensors of an electric bike are very important. They determine the response of the motor and, as such, the way we perceive the behavior of our bicycle; the sensations while pedaling, so to speak. The sensors are devices that detect our pedaling, both in force and cadence. Want to know how they work? We'll explain it simply. While pedaling, the sensors send a signal to the motor. But they don’t do it directly, but through a controller. A kind of guard that filters the signal so the motor doesn’t suffer more than necessary. Once the signal is received, the motor responds with the necessary power to assist our pedaling. Finally, we talk about two elements that are closely linked: the controller and the display.
The controller and the display of an electric bike
Just because they are mentioned last doesn’t mean they are less important. On the contrary. The controller is not visible to the naked eye. Let’s say it is inserted into the guts of the bike’s electrical mechanism. However, it is the electronic brain that controls our e-bike. The controller manages and interprets the commands and signals we send before sending them directly to the motor. Thanks to the controller, we receive pedal assistance that matches our demand in real time. 
A good part of these commands are managed through another fundamental component of our electric bicycle: the display. This is the screen device located on the handlebar of the bike. Through the display, it is easy to control things like speed, distance, or battery charge. In addition, it allows you to program the level of assistance to our pedaling and easily switch from one level to another.
How many levels of pedal assistance are there?
Basically, and depending on the models, there are usually four: 1.- Assistance level 0. The motor disconnects and the bike becomes a conventional bike. That said, a heavy bike. As you know, lightness is not exactly one of the virtues of an e-bike. On the road, the lightest ones are around 11 kg; for MTB, a weight around 16 kg would really be a featherweight. 2.- Low assistance level, better known as Eco Mode. This is ideal for rationalizing battery usage. To give you an idea, it can mean between 25% and 80% additional power compared to the force we apply to the pedals, with our own physical capacity, let's say. 3.- Normal assistance level. It can provide a boost of between 100% and 150% of the power we apply to the pedals. As a result, the range is noticeably reduced compared to Eco Mode. Easily, by 50%, but it depends on usage. 4.- High assistance level. It can mean up to 200% of the force applied by the cyclist. With this level of assistance, there will be neither wind to defeat you nor a hill you can't conquer, but you will drain your battery in no time. Good. Now that you know how it works and the elements that distinguish an electric bike, it's time to choose. But first of all, you should ask yourself: What am I going to use my bike for? But that's another story, which we'll talk about another time.
Tuvalum Team
