How to make an electric bicycle with 4 low-power motors that accelerates to 70 km/h
For converting a bicycle into an electric bicycle, special sets with motor wheel. This is a decent budget solution, but it does not allow you to achieve normal movement speed. The wheel motor on a flat road allows you to accelerate to a maximum of 30-35 km/h. Higher-speed sets are difficult to find, and they are expensive, so you can get out of the situation by installing 4 775 electric motors instead of a motor-wheel. They have high torque and develop up to 9-15 thousand rpm. This will allow you to accelerate the bike on a flat road to 70 km/h.
Materials:
- freerunner (ratchet);
- big star;
- electric motor 775 – 4 pcs. - ;
- corner bracket for engine 775 – 4 pcs. - ;
- sprockets with a landing diameter on the motor shaft - 5 pcs.;
- bicycle chain;
- wires;
- battery;
- controller for electric bicycle;
- speed controller;
- heat shrink;
- nylon ties.
Converting a bicycle to an electric bicycle
The small rear sprocket of the bicycle needs to be replaced with a large one.It must be equipped with a ratchet so that the wheel can rotate after the engines are stopped.
Let's put the wheel back in place.
Next you need to weld the mount for the motors. It consists of 4 standard angle brackets for 775 engines.
They are welded together and welded to the rear fork of the bike, as in the photo. Then the first motor is installed in the mount. It is equipped with an asterisk on the frame side.
Before this, its shaft is machined under the pin. A stock shortened bicycle chain is tensioned between the large rear sprocket and the small one on the engine. Next, the remaining 3 motors are installed.
Then 4 sprockets need to be placed on the motor shafts on the front side of the welded block.
After this, they are connected by a common circuit. As a result, all engines will create torque together and, through the shaft of the first motor, transmit force to the rear wheel. In this case, the pedals can only serve as footrests, since the chain is not connected to them.
The motor power terminals must be connected to the electric bike controller.
Considering the total parameters of the engines, it is unlikely that it will be possible to find such a powerful controller for control. In this case, you can use 2 controllers, each of which will regulate the power level of 2 motors. All electrical equipment is attached to the bicycle frame with nylon ties.
The power battery is also mounted on the frame, and the speed controller is located on the steering wheel.
In this form, the electric bicycle is already capable of riding. In the future, after testing the performance of the selected electrical equipment, the wiring, controllers and battery can be hidden in a case.
To start moving, you need to turn the speed control and the bike will start moving.The speed should be increased gradually so as not to bend the shaft on the first motor. Before you start using your electric bike on a regular basis, you need to equip it with powerful disc brakes. It is important to never brake when the engines are running. Ideally, install a specialized gas and brake handle to adjust the speed, in which case the ride will become more convenient. When braking, the controller itself will turn off the motors.
