I can relate to your description:"On the parked car I whammed my head about as hard as it could have hit anything." That is exactly how I felt. That impact and the resultant freedom from injury had the effect on my mind of a really powerful religious conversion. I mean, it was like I had been born again.And what I had been born again into was the sure and certain knowledge that I would never get on another two wheeled vehicle without a helmet. But I can also relate to your going helmetless just a few weeks later--you do things like that when you're 24. I haven't got that excuse.