The Helite e-Bike fork sensor is optional and does not have to be used for your vest to function. Only the Helite e-Bike Fork Sensors are compatible with the components for your Helite electronically activated vest. The e-Bike Fork Sensor is highly recommended for road use as the detection of impact time is significantly reduced. It allows the overall detection of more accidents, including those at low speeds and when stationary. For example, you may choose not to use the fork sensor on the track, as fewer accidents happen at low speeds and collisions with another vehicle or an obstacle are rare. The fork sensors do not require charging as they have 5 years of autonomy. Please note you would need to pair your vest with the Fork Sensors - it is possible to pair a number of vests to one fork sensor.