My attitude and experience differ from some of you. Most of my rides are on sparsely populated trails and (mostly) lightly-traveled roads. But, I think I’m similar to Jeremy… with a little more detail as follows:
1. I hate road riding. I am the opposite of
@stompandgo. I agree with his comment about loving to see kids out there, etc. But, there are a lot of particularly unfriendly motorists out here in central Massachusetts, and I’ve had some bad encounters that have (luckily) not ended in me getting chased into the woods or something worse… In any case, unless I’m getting a friendly wave (not the finger, that is) from a motorist, I do not make eye contact or initiate anything. I ride the “with traffic” direction (on the right, that is) , and there are very often minimal shoulders where I ride, though I try to stay to the right of the white line if I can — sorry UKers if this makes no sense to you

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2. I occasionally run into asshats riding bikes too quickly (both regular and e-bikes) on the areas of populated trails that I ride every day. These people almost never make eye contact or wave. These people only get frowns from me.
3. In most other cases I keep it down around 10-11MPH and I am always waving, saying hello, and warning pedestrians (or saying “on your left/right/down-the-middle) at a distance when I’m coming up on them. Fättie is an imposing beast and I don’t want to scare pedestrians.
4. I’m usually not passing other bike riders (of any time) unless there are no pedestrians around and I’m going faster (15-20 on the trails) or we’re going in opposing directions. Almost always a wave or a hello in those cases.