Some of you who are comfortable yelling "on your left!" must ride on sparsely-used MUP's. If I did that on the paths here, I would have lost my voice by the time I got home. I use the bell, and if that doesn't work, I just slow down and pass as safely as possible. If you aren't prepared to have to slow and even stop occasionally, you should think of riding on the road instead - which is both faster and probably safer on days when the bikepath is really crowded.