Only when you're passing them on the left imo.

I generally find it unhelpful. People's reaction time sucks and and so many people hear 'left' and jump in that direction before their brain can process. It's not an intelligence thing that some people try to make it seem, it's just that the average person has this interaction like once per year thus don't have muscle memory baked in.

I yell out 'excuse me' from several feet back or ring a bell if I'm on a bike. Or more often just slow down as I normally don't really care.

A few thoughts; lack of infrastructure for pedestrians and cyclists is what crowds us together and forces close passes, try to remember this and be patient and kind.

The individual being passed has the right of way, they have no obligation to make way. The individual passing is responsible for doing so in a safe manner, no passing on turns or where view is obscured, sometimes need to slow down and wait before passing. Always wait for opposing traffic to clear before passing, don't dart out in front of opposing traffic making them slow or take evasive action.

A bell is the most effective and least startling method of alerting others to your presence. People seem to instinctively move right when hearing a bell. As mentioned by OP, calling out on your left sometimes makes people move left. (Not true on group rides with experienced riders, on your left is the correct method there)

Source, decades of cycle commuting and pleasure riding.

Edit: directionally challenged

I've seen this only once or twice, so I think it's exceptionally rare. My hypothesis is that it relates to which leg they happen to standing on, at the time that they hear your call: if they're on their left, making their next step farther to the right is perfectly natural and fluid. But if they're already on their right leg, the startle response might lead them to undo their step, meaning they now step to the left.

But in any case, the distance that you call out to another trail user should be enough so that even if they make a mistake, there is sufficient time to avoid a close shave. If this means riding slower as you approach, then that's what is necessary.

Around me, the trails are marked according to the state guidelines for pedestrians, which is to walk on the left, against traffic, so they can see oncoming cyclists. But even when they choose not to, that doesn't excuse a lack of caution when riding nearby pedestrians. In the end, everyone just wants to get where they're going, without externalized risks, safely.

Pedestrians get the bell. Cyclists get “Passing on your left.” Immenent collision gets a super-loud, urgent “Heads up!!!”

Of course, in the last case I am trying to stop also.

In all cases, any form of acknowledgment like a hand wave ir head nod gets a “Thank you” and polite wave as I go by.

They hear something, and turn in the direction of the noise to see what it was, in this case to their left.

As someone who walks the trails a lot, having someone say "on your left" every two minutes is annoying. Just don't hit me and let me enjoy the trail in silence. The people who are walking need to treat it like the sidewalk that it is and not suddenly jump out where people are biking and running. With half of the people wearing earbuds, they can't hear you anyway.

Hello, fellow cyclist. “Passing on your left” works better than “on your left”. “On your left” makes people whip around for some reason, but adding “passing” helps

Bells are hit or miss due to ANC headphones, though there’s one with a Z in it that almost sounds like an air horn, and the video seems compelling. The Skoda seems cool but they also made it almost like a “hey, somebody else wanna make this”.

For moneybags, make an ultrasonic-speaker setup and just beam it into everyone’s skull at range. :)

You have to do it far enough back for them to process it. Or just ring your bell and let them choose. Headphones always get a repeated bell.

If your going too fast for that to work, then you are going too fast, slow down around other people if there isn't space.

do the Time warp with them as you pass ? and say vale Tim Curry?

It' just a jump to the left and a step to the riighhttt 🗿

https://www.youtube.com/watch?v=u1O2-oFmWXM

BEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEES.

If it looks like someone that may panic, I tend to go with "bike back" and let them figure out what they want to do, rather that try to give them an instruction.

From the skiing world, this is a norm.

Problem is we instinctively turn to the left unless we intentionally counteract it.

I've been on both sides of this, so I'm as guilty as anyone.

Only if you're passing on the left. It would be dumb to say it if you're actually passing on their right.

One time I was riding to work, a group came from behind me and one of them started shouting “left left left”. We were just coming up to an intersection and I still don’t know what he meant: did he want to pass me on the left, did he mean to tell his group to turn left, or did he want me to go left?

Get a decent bell - not one of those little ting-ting ones that you can’t hear - and use it. A bell is always clear: someone wants to pass on the left (right in the UK).

I kinda wonder how useful it is but I think the main thing is any warning and its kinda nice to know where it might be. I get you though. You don't see them coming and so its kinda out of the blue and they are moving fast so by the time it even registers for me they have basically passed. Maybe everyone should just put a playing card in their spokes :)

And here I sit, "Y'all see other people where you go!?" There are places I get into right by my hood and I'd be shocked to see another human there. I assume all noises are animals.

If you're cycling and passing a pedestrian? I ding the bell with enough time to let them step to one side, and then I go through the gap they create. The gap can be on whatever side they want.

I just say the direction I am coming from, typically on the right. So I just yell out "RIGHT"