I was reading another thread and one of the posters mentioned how he had called out "on your left" at 15M and again at 5M and the kid on the bike turned into him as he came by. In my opinion, "On your left" means NOTHING to anyone but another (seasoned) cyclist. I find on the MUP that if I call "On your left" to a walker, they always tend to look down at the ground to their left and then swing around and look. I find it works better to call out "I'm going to pass you on your left." To call "On your left" to a 12 year old kid has the same effect as calling it out to the lady with the beagle on 25 feet of retractable line....NONE. They just don't know what to do, or what you intend unless you express yourself with more than three words.

Just my observation after a couple years of riding MUPs and Trails and road.

Tractor Tom in Okeechobee, FL