As a bike rider and a dog walker I have both problems - but there are always unthoughtful or ignorant people out there. I always use the bell in advance (not right behind them) and when I pass say thanks and often "I didn't want to make you jump". There are dog hating manic bike riders out there (sadly we have a local one) who thinks he not only OWNS the cycle path but its his job to ride INTO your dog, even if he's not in the way! There are always extremes and and nutters and normals on a cycle path/dog path, myself included (though I would hope I fall into the latter category).