I just did not expect somebody to be carrying that kind of speed on a sidewalk, going the wrong way, in a residential neighborhood. This guy was really moving! So now the drill is to check both travel lanes, the opposite traffic for people turning Left, and both sidewalks both ways!
I just know that as soon as I have this drill down, some idiot is going to be coming off the sidewalk behind me to turn Left, and it's back to the drawing board!
The fact is there is no way, in the end, for motorists to protect themselves from accidentally hitting one of these guys. At the speeds they use, being in unexpected places, being in out of sight places (next to your vehicle, say), they can whoosh out in front of you at any time. No amount of checking and careful driving can insulate you (or them) in every instance.
If a cyclist is roaring up on the right side of your vehicle and ignores your turn signal and the fact that you obviously are looking left in preparation for turning right, and the cyclist keeps going and you do indeed turn right and the two of you crash, there is nothing you could have done to prevent that. Only the cyclist could have driven defensively in that situation.
But no telling who would get the ticket or be held liable for the injuries.