There's an old guy that habitually rides an adult trike in Kalispell, MT for most of the Summer months that never gets above 10-mph. Sometimes he rides on the roads with traffic in the lane, and sometimes he rides on the sidewalk. He just takes the path of least resistance and when the sidewalk is wide enough and clear enough and the road has heavy enough fast enough traffic to make the sidewalk the better choice in his mind he uses it and when its the other way around and in his mind the road is the better choice in his mind he takes it - in the lane and heavy vehicle traffic just have to deal with it. I've seen him around for years and he still seems to be doing just fine. Long story short, you don't have to be fast to ride in the road on 25-mph or less low speed, in town, square block, grid traffic. Yes, when he knows traffic is heavy and fast and he knows there is a good unobstructed sidewalk available he uses it instead. Long story short, I rarely say this and it hurts to say it but if you really are so slow you can't mix with that kind of traffic you can probably safely mix with pedestrian traffic on the sidewalk. You won't ever catch me hollering "Get on the SideWalk !!!" to any cyclist on the road anywhere regardless of how slow they were going but I'm not going to give you a hard time if you choose to ride there if your riding slow enough that your not a danger to pedestrians since after all if you ride on the sidewalk you are in "their space". Now if your bombing down the sidewalk at full clip in the tuck with a "Get out of my way, or I'll run you down !!!" attitude towards pedestrians then I might try to let you know that it would be better off for everyone if you were to ride on the road vehicular style.