I set my "personal best" on the last day of a seven-day credit card tour (loaded with rear panniers and HB bag) last week. When I dared to take my eyes off the road for a millisecond, I saw 77.2 kilometers per hour (48 mph) on the computer. It was at this point that, with some breeze out there, I started to feel an oscillation in the front end (I think we used to call it a speed wobble in my motorcycling days). I began to gently back the speed down with the rear brake and things calmed down nicely (kept it in the high 50's kph). There wasn't a single car on the road for the entire descent!
Oh yeah, the descent was 3.8 km (2.36 mi) long (straight as an arrow) and 171 m high (561 ft). For those interested it was heading east on County Road 40 towards Georgian Bay (Collingwood/Blue Mountain, Ontario area
It sure was a "rush" and, yes, a little scary too - it reminded me of my kart racing days.