I had a new set put on todayfrom Motorcycle Superstore and there was a noticable vibation starting around 30mph. I called the installer and he suggested it might be normal breakin. Later I was coming down a hill an eased off the throttle...the steering virbated so much (back and forth) it scared me. Has anyone else had this problem, and if so what is the likely cause? It was running great with the Bridgestones, so it just started... Thanks!