OMG.. that must've been so scary for you. I'm really sorry!! To me atleast, it does not sound like Nino is a threat. He's probably suffering from leash/tied-up anxiety... you know, how they say dogs that spend their life tied up become very agressive? Nino being tied up in public places, unable to run away from fearful things and unable to get protection/reassurance from you, is a much smaller version of the aggression of dogs that are *always* tied up. Personally, I would *never* tie my dog up in a public place for any period of time... because, these days, people suck. People are stupid, cruel, and reckless toward animals everywhere.. especially dumb kids .

It sounds like Nino is scared and frustrated because he can't get AWAY from these dumb people, and you're nowhere in sight. Maybe just try taking him to town with you when some one is there to hold his leash and walk around with him while you're in the store, or just take him to pet-friendly stores (Pet Store, Feed Store, hardware store, etc). To get him accustomed to bikes going by, you should desensitize him to Bikes/scooters/skateboards. Slowly, after desesitizing to a stationary bike, walk him in areas where you know bikes are going by. Keep a far distance from the bike and put him in a sit-stay and give him treats and praise for not paying attention to the bikes.... then, slowly get closer and closer to the bike-riders going by until he's calm and focused on you while bikes are going right past you. Obedience class might be helpful. I don't know if I'd totally recommend a behaviorist right now, it depends on how he acts WITHOUT being tied up and alone. He was probably very scared and just telling the bikers/people to leave him alone