The DDS from Daymak looks to be an easy way to convert most any bicycle to an electric-assist bike. The wheel contains its own battery, motor, and even solar panels to charge it (~.6 miles range per hour of sunlight). It looks like it’ll only work with V-brake bikes (not disc), though will be available in either a 26″ or 28″ rim size…for about $700 next year. The 250W motor is powered by a 12Ah lithium battery and controlled by a wireless handlebar-mounted controller (with its own solar panels, too). Interesting idea! I could see this being useful for commuters perhaps. The extra mass and rotational inertia will detract serious bicyclists though. Check out the product page here.