I don’t really see why you have to announce yourself. You don’t announce yourself in a car when you pass somebody. I ride hard and don’t have a lot of spare air. If everybody is being smart and sticking to their lanes except when forced out you can pass and be passed safely with nobody having to announce themselves. Most of the people I encounter on the trail that complain when you don’t announce yourself are in the middle of the path making it so you can’t get around them without it being a tight squeeze. My favorite was another bike hogging the center line and the guy had one of those mirror thingies on his helmet, hey dude keep to your lane and use the mirror and you won’t get any surprises.
From Page 36 of the "Digest of Ohio Motor Vehicle Laws" ( http://www.bmv.ohio.gov/pdf_forms/HSY-7607.pdf ) (Emphasis added):
When passing to the left, the law requires that a driver overtaking another vehicle do these things:
1. Sound the horn to warn the driver of the vehicle being overtaken that he/she is about to be passed.
2. Signal the intent to pass.
3. Pass to the left of the vehicle being overtaken at a safe distance and return to the right side of the roadway only after the overtaking vehicle is safely clear of the vehicle being overtaken.
4. Return to the right lane as soon as the pas has been safely completed and before coming within 200 feet of any approaching vehicle.
The law must be different where you live.
Exhibit 1.