|Nice mechanical engineering class at Yale has built a bicycle with a spokeless back wheel. One of them, redditor zhoalander has posted pictures and wrote:
As you've probably noticed, only the back wheel is spokeless. This was done for several reasons: Manufacturing the rear wheel/rim was very expensive, so we only had one machined to see if it would work. We knew that if we could get it working for the rear wheel, it would definitely work for the front. But in the end, we ran out of time (class was only one semester long).