A couple of weeks ago I took my bike on it's maiden loaded voyage, some 70 miles from Austin, TX to Palmetto State Park over concrete, asphalt, chipseal, and dirt road (more on my blog - www.work2ride.com)

The gear weighed about 34lbs and I had it balanced left to right (was able to ride easily no handed) and 70% in the rear 30% in the front. The issue with flex in the frame that I had was when I stood to pedal the lateral flex in the frame was noticeable enough that I didn't want to tempt fate and bend the frame, so I stayed seated.

I was also able to reproduce the feeling in the frame when I wobbled the handle bars from side to side (not turn) while riding. Is this normal for loaded touring frames or should I worry about it?

The good news is otherwise the bike handles great even at 30mph+ downhills, no shimmy or shakes at speeds or turns and can't reproduce when not loaded. I also tested moving the weight distribution rear to front to what I guess to be about 60/40 or 50/50; moved the heavy blue bag to the front rack.

Next I plan to try without the blue bag at all and put everything in the panniers.