I think a bell is really useful, like @umop3pisdn said, used 'correctly'. So I've come to the conclusion that 'correctly' could mean NOT ringing a bell at the moment that people are already crossing and you're bearing down on them - you missed your bell window. Ringing your bell well in advance works loads better - by that I guess I mean only about one or two seconds earlier than you actually need people to not be there where your line is.
If you missed the moment, don't ring your bell after that like that douche ringing their bell does. Just suck it up, let people cross, ride at walking pace etc.
You left your white slazenger socks behind again.