I'd imagine that a flat at 30+ mph descent would be hard to control - especially on skinny little road bike tires....and most of us would be hitting the pavement. Every time I get my road bike going over 35-40mph, I start to get tenative and think about all the bad things that could happen.

Professional triathlete, Heather Gollnick (3x ironman champ & former WI resident), crashed during a training ride in 2004. She was descending at 45mph, hit a pot hole and then hit the pavement. She spent 2 days in the hospital with severe road rash and luckily no broken bones. She attempted to defend her ironman title at Coeur D'Alene 3 weeks later. I believe she completed the race, but her results fell short of the victory.