Why do bicyclists think that when they ride two or three abreast on the trails and I am riding towards them that I should have to move way over to the right on my side of the trail because they are riding over the center line? (Sorry about the run-on sentence!)

I hate riding near the trail's edge because if I get too close I am sure to crash. I have to really, really slow down and ride close to the right edge until they are gone. I sure would like to scream after them but they probably wouldn't hear me.

Note: This is never a problem with the "speed" riders. You know the people going a million miles an hour.