Why do so few Polish cylcists have bells on their bikes to warn hapless pedestrians, playing children and other cyclists they plan to overtake?
I guess because many shops sell "naked" bikes without all this useful trinkets, just to make an offer price for a bike to look cheap... So, people just forget about this....
Anyway, excluding the fact, that cyclists shouldn't ride on the sidewalks (except some special cases - like when the street has speed limit greater than 50km/h),
there is just no protocol about using those bells on sidewalks. One pedestrian will shout that you rang at him, the other that you didn't. What is more, behaviour of "ranged" pedestrians varies greatly, one would turn left, the other right, if they are in the group, then sometimes they behave like a bunch of balls droped on the sidewalk...
The best way is just ride on the street...