In Washington, D.C., you now have the option of renting a bicycle that can be picked up and dropped off anywhere. There’s no need to try and find a docking station. And the bike you rent might be powered by an electric motor, saving you the exertion of pedaling to your destination. The nation’s capital is one of several cities that are embracing the next generation in bike-sharing, in which those clumsy-looking and expensive docking stations have been eliminated, replaced by bikes that riders can find and unlock using a phone app. At least one company that offers dockless biking is renting out electric bikes as well.