What range can I expect from an electric bike?

It is a question that we hear every day in our offices and that the user of an electric bicycle takes into account but that requires a somewhat more complex answer than a simple figure. The autonomy calculation of any vehicle, also electric bicycles, responds to a very simple formula that is given by the amount of energy we have, the speed at which we travel and the energy consumption of the vehicle.

Let's take an example with one of our electric bikes.

Suppose we have purchased a Legend Monza with a 36V 10.4Ah battery. Well, the amount of energy we have is 36V x 10.4Ah = 374.4Wh. If we establish a consumption of 5 Wh per kilometer to maintain a speed of 25Km / h the equation is simple.

Autonomy = Capacity / Consumption

Autonomy = 374.4 / 5 = 74.9Km.

However, adapting the model to reality requires taking many factors into account. The difficulty is that the consumption of the bike cannot be accurately predicted.

In the specifications of a battery, a figure is usually used within an approximate threshold, one of the reasons why it is not a round figure is very simple, and that is that we will never pedal on a completely level grade. When we say that a full load allows you to cover seventy or eighty kilometers, we mean that this distance will be correct if we move on a surface without slopes, something really complicated in any geographical environment, so if we pedal up a slope of 10º constantly, probably our battery travels much less distance on a full charge. In the same way, if we go down a slope without stopping pedaling, our battery will last much longer than specified.

The level of attendance is another deciding factor. Normally there are usually five levels from lowest to highest degree of pedaling assistance, with which, if we move at a low-medium level we can extend the battery charge to really long distances. The maximum level generates the maximum power and this obviously causes an extra drain on the battery charge. In the same way, what we like to call “level of assistance of the cyclist to the bike” also influences, that is, when talking about an assisted pedaling bike there are two driving sources: the electric motor and the human motor . These two forces work independently in a system with a cadence sensor, so we can say that the less effort the cyclist makes when pedaling, the less autonomy.

Another factor to take into account is the weight that the motor will move. Once again the estimates are based on standards considered "usual" which are the weight of the electric bicycle plus the weight of the rider. These values are in weights of 20 kilograms for the electric bicycle and 70/80 kilograms for the individual.

In addition, if the routes that we travel with the bike have many stops, such as traffic lights, autonomy will be affected since there is a very high consumption to get from standing still to a speed of 25km / h.

On one occasion, a customer submitted a complaint to our technical department to demand an immediate battery change, as he could not travel the distances specified in the catalog. The shipment was carried out and when the allegedly defective battery was collected, it was analyzed, obtaining somewhat disconcerting results since the battery was working correctly. A few days later the customer called us again with monumental discontent since the new battery did not reach the specified 70/80 kilometers either and it was then that we decided to find out what was really happening. The customer insisted that he moved around the city and unevenness in the road was unusual, and despite always using maximum assistance, it was not logical that the decrease in kilometers per battery charge was so considerable. In the end, it was learned that the customer was 1.95cm tall and weighed 122 kilos, making it impossible to travel 70/80 kilometers on a single charge.

This is why when we buy a battery for an electric bicycle, we cannot know exactly how many kilometers per charge it will travel, but we can estimate a figure taking into account all of the above.