At you thinking you can prove it.
you do understand how mountains are formed in the southeast right? in the west you have HUGE mountains of course, but formed more gradually resulting in modest climbs of 5-8% grades.
here in the southeast, the mountains are not as high, but much MUCH more steep. brasstown bald near dahlonega georgia for instance has a 1-2 mile section that is 20%+ its very difficult to ride your bike up that.
so my point is that its not as hard to achieve very high rates of speed for short periods of time when you're barreling down a descent that is a 20% grade.
i doubt you've ever ridden up or down a hill on your bike in your life to understand how this works.