I am no supper speed hiker, but my natural walking speed is about 4 mph and when I'm trying to knock out a 25+ mile day I tend to mix in some light jogging on trails as well. Overall I average about a 5mph with lunch and everything (don't take many/any breaks). This past weekend I was on a crowded trail with a ton of day hikers out to enjoy the leafs. I was passing them all and one guy I nearly scared half to death as he some how didn't hear me coming even with all the leafs on the ground, a young couple saw me and just decided they would rather have me hike on their heels then let me pass, and another father and son team just didn't seem to care that I wanted to pass even after I asked...
I say hello to everyone I see on the trails, but when approaching from behind its awkward as to when to say hello without scaring the crap out of someone. My wife suggested to do like bikers do and say "passing on your left" or something like that, but there's not really room to pass on the left on most sections of trails. If I could I would, but most of the time I need them to stop and pull over so I can get by.
How does everyone else handle this? I know I got more than a few comments just for walking fast thrown my way after passing, but I don't really care about that. But at the same time I want to be as polite as possible to other hikers and prefer not to scare the crap out of them.