For most of my life I rode sidewalks. I considered road cycling to be a more advanced level for people who could afford new bikes, helmets, lights, etc. Some of my favorite MUPs become sidewalks, so I considered them to be approximately the same thing. The differences now are my bent with 20" wheels and my sore back on sidewalk bumps, and I bought a helmet. I want a smoother ride, but in many areas both are bumpy.