Around 2014, we helped SRAM develop the E-Matic, an enclosed and protected rear-wheel electric assist hub. The device includes a torque-sensor, controller, motor, and an automatic transmission system. It’s powered by rechargeable battery, which includes a gauge to show when it is in need of a charge. The E-matic is the perfect system for getting around locally without exerting too much effort. Check it out at SRAM’s website.