I have a bell on all my trail bikes, but the bell and I'm on your left is almost useless. Over 50% of the pedestrians where I ride have Ipods blasting in their ears. The only thing I can do is I slow down and cover my brakes with my hands, that comes from years of motorcycle riding. It is agravating, but at least I have an excuse for my low average speed LOL. I learned on a motorcycle when you expect danger put your hands over the brakes amd slow down. I still prefer to ride greenways because if I do have an accident there more than likely I'll walk away from it.