The German post office delivers much mail using sturdy e-bikes. Capacity is increased if necessary with a trailer. The electric motor supplements the power provided by the rider, increasing the load-carrying capacity. Royal Mail replaced its Pashley conventional cargo bikes with diesel vans, which will probably go down in history as one of the worst decisions ever made by Royal Mail management. But at least they are thinking again: https://www.bikeradar.com/news/why-i-think-the-royal-mails-electric-trike-trial-is-important/
