I found that ringing a bell will make pedestrians vere from their straight walk in to a wobbly weave as they look over their shoulder and lose the ability to continue in the same direction. This is amplified if there's 2 or more people together.
I'd rather call out "excuse me" or "on your left" or similar as a bell is quite impersonal, which people dont like IMHO. Especially as you're so close you could have a conversation.
The worst ones are those wearing bluetooth earbuds, especially if they're black buds, as you can't tell they won't be able to hear anything. Big obvious headphones you know you're not going to be heard from a distance away so can plan accordingly.