The e-trailer is designed to be as simple as possible to use, with sensors that automatically match its movements with the person in front, whether they’re on a bike or on foot. “There is no push and pull,” Tomiyama says. “The trailer is synchronizing and mimicking the movement in front every millisecond.” It’s also designed to minimize any vibration on bumpy roads and fully carry the load. “You can move 200 kilos [roughly 440 pounds] and you just do not feel any weight behind you,” she says. They can carry more than a lightweight cargo bike, but they’re easy for anyone to handle, unlike typical bigger cargo bikes.