One finds that there's usually an etiquette with bells -- learned in the Netherlands this past autumn that it's Bad Form to ring them too much/too insistently/too whatever. Some places, they barely seem to exist--riding in NYC environs, for example, I was astonished to see how few there were.
I depend on mine--mostly to alert others to my presence, in a discreet, Canajan sort of way. Especially useful, maybe even critical, on mixed-use paths. In Austria, on the Donauradweg, I even had wandering tourist pedestrians thank me for using the bell.
J.