There have been threads about whether or not to wave at fellow roadies when you pass (I always acknowledge with a wave or nod of the head). This sort of ties into that.
This morning I was on a ride with my club when, just about the time I got dropped on a sprint, my rear tire went flat. I called out to them, but they were already out of earshot so I was alone. It was one of the worst places to try and change a tube: On Pacific Coast Highway in Southern California, with cars screaming by, inches away at 60 MPH. The tire was so tight that I had to use a tire lever just to get the damn thing off the rim. I broke out my spare tube, and threaded the cartridge on the head. Unfortunately, I hadn't closed the valve from the last time I flatted, so all the CO2 went woosh! Straight into the atmosphere. I had another cartridge, but now I had no room for error.
Just about then a rider stopped and asked if I needed any help. I told him I could use a hand wrestling the tire back on the rim. We were in the process when one of the guys from my club arrived--he had doubled back to see what had happened to me. About the same time two more roadies came upon us, slowed and asked if I needed a hand. I thanked them and told them we were OK.
I've found that the road cycling community is like a fraternity--no strangers, just friends you haven't met.