Working principle of lightweight electric power-assisted bicycle - rear axle hook sensor

Working principle of lightweight electric power-assisted bicycle - rear axle hook sensor

The gray component in the figure is the "rear axle hook sensor", which is installed at the junction of the rear seat fork and the rear chainstay, that is, the installation position of the rear axle (the red dot in the figure is the rear axle). It is equivalent to an additional adapter, generally made of aluminum alloy. The power of the bicycle forward is transmitted to the rear axle hook sensor through the rear axle, and then transmitted to the bicycle frame. When the rear axle hook sensor receives the force from the rear axle, it will deform, and then squeeze the pressure sensor in the red circle in the above figure, and then mobilize the battery motor to provide power for the electric assisted bicycle. The advantages of the rear axle hook sensor are simple principle, simple structure, and low production price. If the electric assisted bicycle is always used on a straight road, it is also good (used in low-end electric assisted bicycles of BH and GIANT, and Xiaomi electric assisted folding bicycles), but under real road conditions, the shortcomings of this sensor are also exposed - the measurement torque is not accurate and delayed, and the riding experience is poor; the production process of the vehicle is high, and the cost saved by the sensor is transferred to the frame processing; the aluminum alloy material is easy to deform, the service life is short, and the user's subsequent maintenance cost is high. Therefore, the slightly higher-end electric assisted bicycles have abandoned this type of sensor.