Ok, that's pretty bad. About the only thing worse is you are in a public toilet stall and someone in the next stall starts to chat with you. It is a violation of all sorts of norms even if it is a friend, but I actually had a stranger try to make idle chit-chat once at a stall in Heathrow.

As for waving - it all depends on how common cycling is where you are. If you see hundreds of fellow cyclists, you probably wont wave. I dont see cyclists in India or China waving to each other, for example. On the other hand, if there are only a handful, then waving or nodding isnt a polite thing to do.

V.