Originally Posted by
Mountain Mitch
But at sea level you have all that thick rich oxygen. Up here in the mountains you have to have the capability of absorbing the O2 out of thin air.
I find the best way to sustain speeds over 30 (or 40 for that matter) is when no one else is around to record the event or witness it in any way. Then get on the computer...
If you train at altitude and then compete at sea level you get a little boost but riding at high altitude decreases wind resistance considerably and this is why Merckx made his hour attempt in Mexico city... it reduced his wattage requirements considerably and he still said this was the hardest thing he had ever done and would suspect that the altitude affected his aerobic ability. He had demonstrated how hard and fast he could ride in previous races where his numbers were not far off his hour record and these efforts were sustained over much longer distances.
When my friends and I get into somewhat geeky discussions on speed we make it clear that how fast you can ride down a hill has nothing to do with how fast you can ride on a relatively flat course in good conditions... I can do 90 kmh on my bike if the grade is steep enough.