The e-bikes are 90% pre-assembled. You only need to assemble it according to the instructions. Please check the screws before riding. Within this period, we will provide you with free spare parts and you can have free repairs carried out in our authorized workshops. You can find our service centers on our official website. ? S600 is the latest fashionable leisure electric bike from San Miro Company. ? The electric bike is equipped with 1,000W2 dual brushless motors, 48V 17.5Ah Samsung lithium-ion battery, Shimano ALTUS 7-speed gearbox, JUDER 3.0 fat tires and SOLON hydraulic brakes. ? It has a very powerful drive system and can reach a maximum speed of 50 kilometers per hour. ? With this electric bike, you can easily ride on various city streets, mountains and beaches and cope with road conditions such as ice and snow. This is the best electric bike you can own.