It is ok to ring a bell. Personally I find more people are annoyed when they AREN’T alerted to a bike which is about to pass them. In the same way I would be more than happy for a car to pip his horn when he was about to overtake me, thereby warning me to be careful not to stray from my path. Used properly It’s a sign of courtesy not aggression.
It’s always good to be aware of what’s behind you. I use a Garmin Varia rear view radar which alerts me of any vehicles approaching from behind. Interestingly it’s also a rear light and it changes its flashing pattern when a car approaches. I’ve found that cars are much more careful in their overtake when they realise the cyclist has been alerted to them. Maybe they are assuming this high tech light is also videoing them?
flashing red light on a pathway; he was, of course, ignoring the fact that prior to and immediately after the pathway are roadways, where, many a time, I've had to pick myself up from to hear the plaintive words: "Sorry, mate, I didn't see you."
