My commute starts out with a 15% descent. If I make the light at the bottom of the hill I'm easily rolling out on the Interstate overpass at 52-53. Best ever indicated speed was just over 57. If I have to stop for the light I'll still have a max speed of 48-49. Granted, this is measured with my bike computer, but when I've ridden along with both the bike computer and the Garmin 301side-by-side the bike computer was indicating a pretty accurate speed. Even with a margin of error for the bike computer I'd say I'm still getting into the 50's. Cars seldom pass me on this descent. Sadly, I have to go up that same hill in the afternoons...

--Marcus