I have a bell on my path bike but rarely use it. I feel that I and the folks I am passing are more comfortable with "I'm on your left". I think the "I'm" part helps them know that I will be on the left so you move to the right! If hubby is with me I will call out "We are on your left" so they can expect more than one rider. It seems to work well around here.

Our paths go under roads via tunnels and i use the bell to alert others that I'm coming through the tunnel to avoid a head-on collision!