Revisiting this thread, now that I've since ridden on two mixed-used trails in our area. A lot of cyclists here prefer to shout "Left!" to pedestrians instead of using bells. Unfortunately, some of the pedestrians who walk these trails do not speak English as a first language. In general, they cannot be trusted to respond predictably to "Left!". There was a 60-something year old woman who was struck by a cyclist because when she heard "Left!", she turned to her left instead of making way for him by moving to the right. It doesn't help that the cyclists who are flying up and down these trails don't give warning until they're only 5 feet behind the pedestrian. I suspect most of these cyclist-pedestrian fatalities and other accidents are due to the cyclist not slowing down and not giving adequate warning.

On the way to the grocery, I had to ride a sidewalk to get to the mixed-use pedestrian bridge. On the narrow part of the sidewalk, there was a woman walking ahead of me with 3 dogs - no room to pass. Shouting "left!" or ringing my bell would be no good there, so I had no choice but to dismount and walk my bike behind them, until the path widened enough.

I'm finding that I'd rather just slow down and quietly pass each pedestrian, unless there are two or more walking abreast, in which case I ring the bell. So far I only had to ring the bell once - this was for a pedestrian who was taking up both lanes of the mixed-used trail, absent-mindedly weaving between both lanes. She didn't worry me though as much as the cyclist who was coming at me in the wrong lane. I slowed down and looked him in the eye until he changed to the correct lane for his direction. I guess he's just too used to cycling on the left lane, presumably in his country.