When riding bicycles on a sidewalk, trails, walking/biking paths, bicyclists should yield the right-of-way to pedestrians. They should call out an audible signal (i.e. cyclist left/right, etc.) before overtaking and passing them in any and all situations.
To pass walking pedestrians quietly without an audible signal to start with is very scary, and could cause an accident and injuries. It is a known fact that walkers walk in pairs and/or three abreast when no bicycling is in the area, and they cannot see behind them when a cyclist is approaching. A courtesy call prior to reaching walkers and others would alert them to move to allow them to proceed and pass the walkers. It sounds right to me.
On a recent walk with friends on the Augusta Canal Towpath, we experienced several cyclists who nearly hit us without mentioning they were approaching us. Some do and some don't. The ones who don't are the ones I am talking about.
Cyclists, please give consideration to walkers as you wish automobiles give cyclists and possible accidents can be avoided.
North Augusta, S.C.