"In the meantime and as a first step, how many of you could either confirm or reject the hypothesis based solely on your own behavior. Are you more prone to acknowledge/greet others out of a sense of kinship when there is some level of hardship involved?"
Yes, absolutely, and not only when it comes to bike riding. For example, my house is in an area that floods when there are bad storms. Those storms (and the cleanups) bring out the best in people - it's at those times that we all act like neighbors. When things are relatively calm and easy, we might just nod or say hello.
I've also noticed that, when people are stuck on long lines, or on a subway train that's stalled in a tunnel, strangers will start to talk. When things are going well, everyone pretty much keeps to himself.
I don't think this is a new observation, BTW - I think it's well known that adversity brings people together. When it doesn't tear them apart, that is...
