My worst near misses have been when an out of control bike came at me unexpectedly. Three or so times I've had to dive off my bike to avoid a head on collision. That's why we (nowadays my wife is with me most of the time) try to ride off road where there are few others. Fortunately it's pretty easy in socal since there are many places available. Also, there are remote bike paths if that's our preference on a given day.