"ding"

One accessory I got right out of the gate was a Bell. After being a "Walker" for several years, I became extremely cautious and aware of bicyclists over time. Around 80% of them do not abide by the following sign:

Of course I don't know what exactly happened last year when that old lady was killed by a bicyclist, but I would wager money that the bicyclist didn't give a warning, he/she was going too fast, and when the lady realized he was behind her, she stepped out - the wrong way, right into his path.
Even with me being as alert as I try to be, a few weeks ago I just sensed someone coming up behind me, and when I turned to look, he was only a few feet away. If I had reacted the way that old lady did, I could have ended up dead meat. He was cookin'!! Fortunately, I froze, like a deer in headlights, and he did a left-right-left squiggle with his bike not knowing what I was going to do, and there was no collision. This all happened in a split second.
Anyway, I do a "ding" with my little bell when I'm approaching someone from behind, and like I did as a "walker", some of them even say "Thank you"...