For the preparation of thesis I have chosen the designing and constructing of electrical bicycle. The advantage of own electrical bicycle constructing is in the fact that bicycle can be much more powerful in comparison with the electric bicycles on the market. During designing and constructing I have faced so far unknown problems with the geometry of the bicycle and the technical requirements. At the end all roblems were solved successfully. The biggest concern constructing our own electrictrical bicycle is for first instance: for which purpose we intend to use the electrical bicycle and what kind of bicycle performances we are targeting in terms of maximum speed, driving radius and power. If we use electric bicycle for everyday suburban traffic on straight roads, we can choose a smaller motor and at the same time increase the capacity of the battery, to thereby increase the range of bicycle. However, if you want to drive off-road, along the paths or hilly terrain, we have to choose a more powerful motor and more powerful controller. In doing so, we must not forget that the faster electric bicycles require a higher total voltage and for driving heavier loads require higher torque electrical machine. When I start desinging and searching for all different options available, I have faced a lot of new characteristic properties of components. Therefore, in my thesis, for easier understanding, I dedicate more attention to the descriptions of the components, which play a key rule in electrical bicycle designing and constructing. Constructing of electric bike started on the basis of an analysis of the mathematical model, which provides consumption of electrical energy, depending on the distance traveled, the necessary power to overcome driving uphill, defiance air resistance, friction, etc. A special chapter was dedicated to the current weakest link in the era of electric vehicles, power supply.