I have seen pictures of, and in person, cyclists with that triangle on the back of the bike. It's a good idea, so is a
Daylight visible tailight.
Drivers go nuts over all slow moving vehicles, tractors, trucks, backhoes, etc. But the cyclist looks powerless to retaliate. Most drivers who are not cyclists do not know any laws pertaining to cyclists on the road either. They may think you need to move over. Just as they want the tractor to move over.
If you yell at a guy in a noisy tractor or truck with closed windows, he can't hear you. And he can block your car intentionally. So take it out on the cyclist.
