In many cases there will be an Alpha male, stop him and often the pack will be restrained. I may have mentioned this but to those who poo poo dogs as not really dangerous, on October 1, 2005 my partner and I were chased by 2 Saint Bernards. I've never seen such large animals move so fast but luckily for me I was riding in the lead and had just enough angle and sprint to get away, my partner was not so lucky. He got hit hard and was bitten. He broke two ribs, lung was punctured, and sustained two cracked vertebrate. End of tour and several weeks out of work. I don't play around anymore because even the small ones can get caught up in your wheel and cause a fall. I yell loudly and if they don't respond then out comes the good stuff.