Before using an electric bicycle, the tightness of the chain should be checked. Cycling with a chain that is too tight and pedals is laborious, while if it is too loose, it is prone to shaking and rubbing against other components. The sag of the chain is 1-2mm, which is more suitable. Generally, it can be adjusted appropriately when riding without pedals. When adjusting the chain, first loosen the rear wheel nuts, evenly screw in and out the left and right chain adjustment screws, adjust the tightness of the chain, and then tighten the rear wheel nuts again.