A regular, commuter style e-bike with decent sized battery weighs around 23kg. Electric cargo bikes on the other hand are more around the 30kg mark. Overall, the motor and battery can add from around 4 to 6 kilos over a non-electric bike of the same style. Of course, this extra weight isn't as significant as it may sound, as the electric motor allows you ride along easier than before.
There has been some innovation in the ebike market recently from companies such as Specialized and Brompton, who now offer ebike systems that are significatly lighter than their full-power counterparts. You can find these models on our website by clicking on the links above.