E-bike basic knowledge FAQ: Everything you need to know about the e-bike motor & battery!
Adrian Kaether
· 07.10.2025
MotorPower: All at 250 watts?
Specified in watts (W). The rated or continuous power, which is specified as 250 watts for most motors, is merely a theoretical value. In reality, the peak power determines how hard a motor can push - and this can be significantly higher. The peak power applies under ideal conditions, i.e. in the highest support level and at an optimum speed. The motors usually only deliver maximum power at pedalling frequencies of 75 to 90 revolutions; rear wheel motors require a certain minimum speed for this.
Support factor
This is given as a percentage and expresses the ratio of the motor power to the rider's own pedalling power. The factor increases with the assistance level and can range from a fraction to a multiple of the rider's power: powerful motors such as the Bosch add up to 400 per cent of the rider's pedalling power in turbo mode - up to maximum power. In other words, with just 100 watts of power, the motor adds 400 watts on top. The factor can usually be individually programmed for the various support levels via the app.
Boom at the bottom: The torque
Specified in Newton metres (Nm). In practice, this mainly determines how strongly the bike accelerates over the first few metres. It is more relevant for gravel bikes or mountain bikes than for road bikes, as it helps on steep climbs and when overcoming obstacles, for example. The values are mostly around 50 Nm for lightweight mid-drive motors. Full-power motors for e-MTBs and touring bikes tend to have 85 Nm and more. The specifications for hub motors in the rear wheel should be treated with caution: they are usually converted in order to be able to compare them with mid-drive motors. In fact, they are significantly lower because the torque is applied directly to the rear wheel and there are no transmission losses. High-torque motors in particular can require careful handling on loose surfaces.
Battery capacity
This is specified in watt hours (Wh) and indicates how much energy is in the battery; this directly determines the range. For racing bikes and gravel bikes, 200 to 400 Wh is common, for mountain bikes it can be up to 800 Wh. The capacity can be further increased with an optional range extender - a smaller additional battery that is usually located in the water bottle holder. Whether larger capacities always make sense depends on the area of use, your own fitness level and your budget.
Paper tiger? Range in kilometres
This figure is only an estimate and should always be treated with caution. It depends on many influencing factors, such as the assistance level, the system weight and the percentage of incline. In the case of road bikes, there is also the fact that the motor is often not active for large parts of the ride above 25 km/h. Mountain bikes, on the other hand, consume significantly more battery power on steep climbs, see "Ride height" below.
Reach height
The figure in metres of altitude is more meaningful because it assumes that the motor is constantly delivering power. In practice, it is usually the metres in altitude that drain the battery. The reach height also depends on the support factor, system weight and the gradient. However, comparable values can be determined in standardised tests. For most road bikes and gravel bikes, riders weighing around 70 kilograms can expect to cover around 1,000 metres in altitude at the highest support level. For e-MTBs with large batteries, 2,000 metres in altitude are possible. At the lowest level, up to 50 per cent more is possible. However, the journey then takes much longer.
Adrian Kaether
Editor
