Originally Posted by HillRider

Been there, done that. You are right, it's a dreadful experience. Fortunately mine broke while I was just getting started from a traffic light so I was barely moving but I went down hard anyway. Sobering to think I had come down a winding 35 mph hill just 5 minute before the break.

The stem that broke was a Profile Pursuit that had a very thin, full wrap handle bar clamp. The single 6 mm binder bolt snapped and the clamp was so thin that it "unwrapped" and the the bars came right out of it. I called Profile to report the incident (no, not to threaten a lawsuit) and they replaced the stem with a much stronger H2O at no charge and were very apologetic.