A bike wheel with an open air center without visible spokes would necessarily have to impart momentum across the top or bottom of the wheel, rather than the center, otherwise the momentum wouldn’t have a medium to travel through. The simplest method would be powered wheels set in a semicircle above or below, with a matching unpowered pair on the opposite side of the spokeless wheel. Or the chain loops all the way around a wheel fully enclosed in a large load-bearing construct. It’d look futuristic. Someone get on it, I can only get high and offer engineering ideas so often.