[large capacity battery]: 17.5an battery supports max speed: 31mph, is equipped with a smart lithium battery charger for fast charging (4-6hrs), endurance mileage up to 55 milse. [3 working modes]: ebike & assisted bicycle & normal bike. with the lcd 5-speed smart meter button, you can choose the electric assist level according to your needs. [upgrade configuration]: professional 21-speedshift, 6061aluminum alloy frame, ,160 double-disc mechanical disc brakes at the front and rear,ipx5 waterproof performance, heavy-duty horns, and lights. [chaoyang tire]: multi-terrain application, marble pavement, cement road, carpet, blind track, etc. durable in all condition road--more than safe, balanced, fast, and stable for your cycling. [good riding experience]& equipped with multi-functional lcd display,adjustable seat, high brightness front light, anti-skidding fat tire, increase stability, comfort, and energic riding experience..syi