I give them a ding or two from my bell, usually with the comment "you're OK" which seems to work. They turn to spot me, then continue on thier line, or move right, which is my intended purpose.

My comment is usually taken as friendly, so we're all happy.

I've not had a problem when I say "on your left" when passing with someone pulling to their left, although I'm sure it's happened. I have seen more than one instance where a club ride was starting to move along and someone passes on the left, or right, and doesn't announce their presence and the cyclist further forward starts to change lanes. I had a close one last week and I've seen more than one this year alone. So yeah, I announce I'm passing.
If the double pace line is well formed and for some reason someone drops out of the line, no I don't announce I'm moving forward, that's undertood.

Bells never worked for me, mostly because in my area they are associated with preschoolers on trikes with streamers. "On your left" usually causes confusion too many posters described above to repeat again. I found that what works the best for me in my area is to bark "watch out!", not to expect any predictable movement and simply point the bike into the void created wherever it might be.

SF

The riders you are passing are under no obligation to move out of your way. If you warn them you are passing then they are obligated to maintain course and speed while YOU safely maneuver around them.

Certainly saying nothing might be acceptable in cases where nobody needs to move, but an annoyingly large percentage of the time people are walking side-by-side taking up the entire trail with their backs to me, are on the wrong side of the trial, or are one the correct side of the trail but their dogs are on- (or worse, off-) leash on the opposite side of the trail. Then what? I try "excuse me," though it sounds peculiarly polite.

+1, I say "excuse me" a fair amount.

casual bicyclists dont know what you mean when you say "on your left". They think it means they are commanded to move left. On the other hand, cyclists know what you mean when you say "on your left" as in you are going to pass them on their leftside. I heard "on your left" over a hundred times in the span of nearly a decade riding. I usually get passed on long descents and relatively flat roads. On climbs its not really necessary to say "on your left" because both parties are moving slow enough that the person about to get passed will notice the rider behind him through peripheral vision. Only idiots ride all over the road and require someone to say "on your left" on a climb. Its definitely necessary to say "on your left" on descents because of the speed. The faster you are moving, the more necessary it becomes. On flat roads you might have to say it if you are moving much faster than the person you are about to pass. If you are barely moving ahead of this person he or she will probably notice you with his or her peripheral vision as you move around the rider.

Just practice shouting this phrase at the top of your lungs: "GAAAHHHH! NO BRAKES!!!!"

(For the sarcasm impaired, I was kidding.)

I'm pretty sensitive to the "on your left" thing because several years ago (before I started cycling) my mother was jogging along an MUP when someone yelled the same words to her. Of course, she instinctively moved left, got plowed by a pretty fast moving roadie, broke her arm and shoulder, and was out of commission for several months. These days, I'll still use "on your left" because I still think it gets the message across better than most other things (I don't have a bell), but I always slow down substantially and expect whomever I'm passing to move left. When I know they won't, I pass, and sprint to get back up to speed. Works my sprinting and no one gets hurt.

Sometimes I'll just pass without saying anything so long as whomever I'm passing is safely on one side or the other, but I'm gotten several gasps and screams so it's still uncomfortable.

Of course, if someone moves to let me by, I'll always say "thank you" in response. It's a hell of a lot easier to say "thank you" to someone than anything else.

I'm considering getting a bell one day, but I'll need to work on the beard first

lol

I wonder what would happen if you came up right behind someone, and yelled "OH MY GOD!!! WATCH OUT!!!".

Someone do it and post a vid. lulz will be had.

In all seriousness, I'm torn about calling "on your left". If I'm on a MUP, I simply accept the fact that I won't be going as fast as I would be on the road, and I slow down until I can pass pedestrians with a wide margin.

A few years ago, I was passing other road riders on a group ride. It was a club-sponsored metric century with about 3,000 riders on various courses. Someone who I had passed on a downhill announced somewhat indignantly, "There's a rider passing without calling it out." I didn't want to say "on your left" because of the large number of riders on the road (would they know who I was speaking to?), as well as the fear that they would veer left in to my path. I was not buzzing people, and as someone (umd?) noted above, if they can't handle being passed with a safe margin, should they really be riding on the road?

"On your left" only works for those understanding what the term means. Same with "Hit the deck", etc. If you have no familiarity with such terms you will likely look around trying to figure out what the hell is going on.
I'd suggest a small bell on your handlebars. The "dinging" sound carries far and is a more widely understood notice of someone approaching. Whether they get out of your way or not is another thing...hehehe.

I generally give a whistle when approaching someone. I'm far enough away to be heard clearly. I pass with more room between us than normal to create a safe buffer...but I ride on nearly empty, rural roads and it is easy to give a wide buffer zone if necessary. I always slow down for a few seconds to say "hi", "great day for a ride", etc. then I'm on my way.

I've found "Good Morning" "Good afternoon" and "Hello" to work equally well.

Bottom line is that you need to pass only when it is safe to do so, and in a fashion that you're not depending on any particularl action from the rider(s) you're passing.

The "Good morning" bit is just a courtesy so you don't startle them, which can be upsetting to newer, or less skilled riders.

Really it's situational. If I am on a charity or club ride, I expect people to know the basics of cycling etiquette. Ill call "on your left". If there is a pack riding three abreast and on the center line I'll call "passing on your left". If I'm out amongst civilians I just slow down and call out "coming up behind you" or something that makes the point. I really really hate riding a big charity tour and trying to pass slow riders considerately while some d0uch3 on a time trial bike blows by inches to my left without a sound. Being passed doesn't hurt my feelings. Just let me know.

last time I used "on your left" the guy screamed like a school girl, turned his bike sideways and stopped.

Luckily, I was going slow enough to stop.

The bell has really worked best for me as well. I ring it when I am still really far back. Generally, they will look back, swerve around a bit, and then hold their line by the time I get to them. Works as good as anything.

I was at a regatta coaching over the weekend (rowing). Coaches commonly follow the races on bike, and this course has a really nice bike path, so TONS of coaches. None of whom know how to ride, and despite the fact that there are TONS of people around them, will occasionally just swerve blindly as if they were the only living creatures within miles. I had one hit me doing just that. I had a TON of room to his right (I was going through a big parking lot, there weren't really lanes. He was probably 4 feet to the left of me. JUST as my front tire is even with his back he turns his bike 90 degrees right. I mean, the wheel might have actually gone PAST 90. This was completely out of nowhere, I had been watching him ride straight for quite a while. He caught my left leg, but not hard enough to go down.

I couldn't find anything to say to the pedestrians that helped very much, without yelling VERY loudly and sharply. Mostly I just tried to do the weaving myself, and I only had that 1 little collision. It is amazing how shocked people are to see a a bike when there are about 40 of them riding along a 1.25 mile race course.

EDIT: AMFJ, that is hilarious

Most cyclists (not all) don't seem to get it.

Anything more complicated than "passing" is too much to process in a split second. If one considers the closing speed to a pedestrian, yelling is required to be heard at the distance you must announce your arrival. If you're close enough to be heard in a normal voice, you don't give the other person time to react and you time to stop in the distance left. Most cyclists do not seem to understand human reaction time, stopping distance, and speed at all.
According to an on line converter 10 mph is equal to 14.6 feet per second. To allow someone to react and know what to do, and for you to stop your bike is about 2 seconds (approx) If you say passing at 14 feet away you already have no time to stop safely if they go the wrong way. You really need to be about 30 feet away at only 10 mph at this distance you need to yell. I don't see any other cyclists doing this. Many say quietly when right beside me "passing on your left". At that time the announcement does no good. At that distance just pass.
At 15 mph you will go 22 feet in one second. Do you give 22 feet of distance and yell, when going that speed? Then plan for an impact. The overtaking vehicle is always the one responsible to avoid a collision. I rarely see a cyclist do this safely. Most drivers do not get this either, they mostly tailgate. If there is a panic stop from the car in front they must hit them very hard.
The closing speed and cyclists perception of time is what the biggest problem is.

There is only one person you can count on, that's YOU, not another person. Yes there are lots of idiots around, yes it can be annoying. Don't give them a chance to hurt you. It's safer and less stressful if you take control by allowing time for others to do the wrong thing.

Don't expect others to do something for you in one second. On an mup or a bike path you need to go slow, that what all the rules say anyway. They are not wrong.
This is a good reason to ride on the road. Drivers, peds, other cyclists will be more likely to expect something coming faster. Of course there are always those who don't. But it's more likely. It's up to you to ride where you want. It's up to you to pass peds safely.

Of course yelling "Passing!" instantly followed by a loud "WOOF WOOF" and "DING DONG" simultaneously either gets results, or cardiac arrest. Hopefull they fall to the right when they die.

Agreed. And the safest way imo is to say nothing. They're going to get startled. I'd rather it be after I pass them and not before when they have time to jump into my path.

Two points I didn't notice here (though I may have missed them).

I try to say "Passing on your left please." The leading word "passing" announces the upcoming event and serves as an attention getter before the crucial word "left". The word "please" announces it as a request rather than a demand, and anyway, people usually respond better to courtesy.

The time element is important. What bothers me as the recipient of an "on your left" warning is when it startles me by being unexpectedly loud from someone unexpectedly close. Such warnings come so close to the time of the actual pass that I wouldn't have time to react anyway. If I'd known that rider was there (which is usually the case but not always) he/she wouldn't have needed the warning anyway, but if I didn't I'll need more lead time than that.

+1 on MUPS. Yesterday along the Charles River I had to pull off the path completely and stop and wait because some 30-something guy was walking towards me backwards 30 yards in front of me. His wife (or SO or whatever) eventually got his attention so he turned around. I smiled at them because I thought it was amusing, but he gave me a sour look like I'd done something wrong. You wanna' walk backwards along a dedicated bike path, it's your own mistake, buddy.

I used to run a lot at a fairly quick pace and occassionally passed cyclists on a MUP, especially on sections right after crossing intersections. It was fun to yell "on your left" and the look when they see it's a runner.

"Passing on your left, please" is pretty cool when it can be heard. Unfortunately by the time it is clearly heard and understood you are probably so close that if an incident were to occur it would at that time.
I still prefer a warning of some sort from a reasonable distance, I do the same when running after scaring the beejeesus out of a couple of people that were walking along and didn't realize I was there.
I've done very very few charity rides though I've wrenched, etc at a few over the years and it is my experience from observations that you get the most people without any group riding or riding experience that are the most apt to be "unpredictable" and make moves that seem bizarre.

When you are on your bike you are in control of the situation and must be the person that acts in a safe and courteous manner for everyone...it is kinda/sorta like "defensive driving" though I prefer the term "offensive driving".

I usually just say "coming up" and pass on the side with the most room--usually the left

I agree that it is much better than saying anything when you are close to them.
It is possible to pass the one person that decides to turn into you just as you pass. It did actually happen to me once. But, it certainly is rare. The only way out of that is to yell far enough away, and slow down, or even stop, if one needs too. I have seen a few peds just turn around into the other lane instantly with no warning and start walking the other way. But I was not very close.
Yes stopping or slowing is a royal pain, but it works every single time. I do pass quietly sometimes on the road bike. Bailey's trike is so slow and so wide, and the dog is so !@#$% loud that I announce a long way away, and somtimes slow to a crawl. It does not matter much in that case I'm only going 10 mph anyway. And I don't mind stopping if it protects me and the dog both. In some cases I need enough time for a dog being walked by an owner in front of us to go nuts when Bailey barks, drag the owner around, or even pull the owner over, right in front of me, face down onto the pavement!!! (It has happened ).
Or depending on the path, it may be possible to pass far enough to one side to even allow them to take a step to the left. I have also noticed that even on my quietest bike, a person walking a dog may not hear me, but the dog can. In that case be prepared for a huge mess of dog, owner, and leash all over the @#$%^&*()*&^%$ place. If I ever walk my dog near a bike path I wear my Take-a-look bike mirror on my sunglasses. I'm never surprised by quiet bikes coming from behind that way.
I suggested it on the forums once, but like anything new or unusual, no one ever understands.