From Southern California, when approaching slower traffic from behind on bike lanes and paths: "On your left" meaning that you are passing them on their left-hand side.
Only left.
People hear the "On" portion of the call and they start moving to their right.
I can't ever recall hearing "On your right".
Good thing, too.
Would be a mess.
bicycles.stackexchange.com/users/12866/user12866
I send a single "ping" with my bell.
More pings only if I don't see the other person recognizing me
(e.g. look at me, wave a hand, change direction etc).
bicycles.stackexchange.com/users/12875/Steffen Uhlig
I've noticed over the years that if I call out it startles people walking.
Most walkers don't expect someone on a bicycle let along someone calling out something they don't understand.
So my strategy now is when I get reasonably close I cough.
Yup cough, it is a familiar sound and if it's on a quite street the walker will usually turn around to see who's behind them.
As a pass I give a friendly wave and sometimes a polite hello.
bicycles.stackexchange.com/users/112/John Dyer
In Dayton, OH, the protocol seems to be sneak up on them and shout as your tire starts to overlap.
Majority of riders tend to not use bells (and only shout when it is too late) and a smaller slice have the miracle bell (miracle if the other person hears it).
However, I have installed dual action bells on all our bikes (or a bugle on my sons) and it allows us to notify at a farther distance with a greater chance of hearing us.
This works for both Bikes and Peds.
People responding to it tend to be less jumpy than when I used to shout.
It also saves my voice on the busier days.
bicycles.stackexchange.com/users/6782/BPugh
Bristol, UK: "Passing on your left/right" usually works, but every once in a while peds (or even cyclists) will move the wrong way.
To be on the safe side, I just bell from a good few yards back.
If that doesn't provoke a shoulder check, I just roll up slowly and issue a polite "'
Scuse me, mind if I pass?
"... I think that's probably the best all-round approach
anyway - why should pedestrians on a shared path be expected to know "bike lingo" like "on your left"?
If it's a numpty with headphones, I find a very quick "pip" with the AirZound works wonders ;)
If it's a runner, or a slower cyclist, who's obviously sticking to the left, I just pass on the right with ample space.
bicycles.stackexchange.com/users/11489/linguamachina
Germany: (I should explain that I'm mostly biking to get to/from work, so this is about urban streets.
But when I ride for fun on weekends, on the relevant paths there's seldomly so much traffic
it requires significant regulation.)
If there's a street present, usually pedestrians are on the sidewalk and bikes on the street, so there's no conflict.
If there's a dedicated bikeway, I ring the bell from as far away as possible considering hearing conditions if pedestrians are on the bikeway, or to overtake another bike.
On the bikeway, the usual rules apply (drive right, overtake left), so no need to announce the passing direction.
Combined bike/pedestrian ways are an abomination which I don't use (biking on the street), fortunately they're largely illegal by current regulations.
On a path in the woods or fields, there's usually traffic in both ways, so pedestrians as well as bikes tend to keep on the(ir)
right side, allowing normal overtaking (giving a soft ping with the bell to notify).
If there's a larger group blocking the whole path, the same as for bikeways applies.
bicycles.stackexchange.com/users/10958/Stephan Lehmke
I post an answer but looking for other answers and will not give the check to my answer.
I live in Houston and the common protocol is bike left or bike right.
Bike left is bike passing on the left.
If the pedestrian does not know the protocol they will turn look to the left
so things can go bad.
If it looks like an experienced runner they probably know the protocol.
Pedestrians don't do a good job of staying right.
And if you have traffic both ways you may drop off the path and pass on the right.
We get some bells but they are mainly Europeans.
When I hear a bell I look for an ice cream truck.
For a couple hours a day a 1 mile loop is shut down and get some racers training.
It can be a problem there.
You will get kids learning to skate and all over the road.
Racers can get irritated and it is not always a polite exchange.
I have a pretty loud cassette
so on the sidewalk I just coast and let them hear me.
When I lived in Seattle there was more use of bells.
Also many more blind turns.
And pedestrians did a better job of staying to the right.
On the trails the protocol is rider up or rider back.
Going into a blind turn rider up.
Then when you pass you call out how many riders are behind you - e.g. 2 back or if none then clear back.
A runner will call out runner up.
I guess if they passed you they would call runner back
but I have never been passed by a runner.
bicycles.stackexchange.com/users/7785/paparazzo
Western Australia: It is a legal requirement here to have a bell or warning device fitted.
I have bells on my bikes and generally only use them when approaching pedestrians or cyclists who are either making it difficult to pass (e.g., walking wide or in the centre of the path) or who I feel may make a sudden move that could prove not so good for either of us.
This is a bit topical here at the moment following the death of a 95 year pedestrian who was hit by a cyclist.
There where on a shared use path.
No details beyond the ABC news report .
Andrew
bicycles.stackexchange.com/users/12823/Aushiker
A question on a bell had a lot of comments on how to notify pedestrians.  How do you notify a pedestrian you need to pass?    How do you notify a bicycle you need to pass?  I imagine this will be region dependent so please state your region.  This is getting a bit of response and it clearly varies by region.  I will give it a couple more hours and just award the answer to the most votes.
Polite/Proper Way To Notify Pedestrians and Bicycles
bicycles.stackexchange.com
<commuter><noise>
bicycles.stackexchange.com/questions/23453
bicycles.stackexchange.com/users/7785/paparazzo
A single ping on the bell a few meters away is considered a polite way to let other cyclist and pedestrians know of your presence. Unfortunately most riders do not use bells, or at least not often enough and not until it is too late. Shouting out is considered a bad idea as it tends to startle people.  A bell is a good way to warn someone that a bike is coming, although a dual action bell notifies people at a greater distance. Cyclists are usually better than pedestrians at keeping to the correct side and following protocol, and sometimes people will move to the wrong side if you call out where you will pass. Sometimes passing where there is plenty of space is the easiest option.
A bell is a good way to warn someone that a bike is coming, although a dual action bell notifies people at a greater distance. Cyclists are usually better than pedestrians at keeping to the correct side and following protocol, and sometimes people will move to the wrong side if you call out where you will pass. Sometimes passing where there is plenty of space is the easiest option.