I'm lying here with a cracked pelvis, fractured wrist and quite a bit of road rash, wondering if anyone has any ideas why I had a tank-slapper on my 2006 SportClassic 1000? The conditions were not what you'd normally associate with a tank-slapper: warm sunny day, straight smooth well-surfaced road, cruising at a steady 120 km/h (75 mph). I remember the bars oscillating once, then much more fiercely, then very fiercely a third time, and I was on the tarmac. No warning signs. Had enjoyed two hours of mountain passes with no hint of trouble. Been riding for 48 years and never experienced anything like this. Not had a chance to inspect the bike yet due to prone status, but am told there are no obvious mechanical issues. Any ideas?