Whenever I ride on a road that is too narrow for passing, and I know I've got one or more motor vehicles behind me, I will always wave a thank you to them when we eventually reach the point where it is safe for them to pass, to show that I appreciate their patience.

If I can find a safe place to pull over, like a driveway, I will let them pass before the road widens. Especially if I'm chugging up a hill at < 10 mph. Unfortunately I'm usually not able to find a pullover spot.

If I'm getting honked at by the driver behind me, then the heck with them.