I'm officially an Old Fart this weekend celebrating 32 years on fat tires. woot woot. "Back in my day", racing out west, we would say "on your left/right" depending on which side was the safest.  Even in a race the vast majority of racers will give you the pass.  Nothing worse than having a stronger racer riding your wheel.  When Free riding I always take it easy and follow for a bit before saying in a friendly way that I'd like to pass. A big smile and friendly word for anyone I see on the trail. Never had a problem.  Except for that young lady on Greenslick a few years back...and what the hell was she doing riding up that section?!?