I used to listen to the radio/mp3 player when I commuted on the MUPs. I was almost run into by a rider coming in from one of the side trails. He wasn't looking for me. But I could've heard him if I wasn't plugged in. I ride mostly on the roads now. I've tried the one bud in one ear thing. It didn't seem to work. Personally I think it's a bit dangerous... for me I get too caught up in the tunes to focus on the road and traffic. That's just me, though.