Originally Posted by Birdmove
That is amazing. I just have a mountain bike, and it certainly is geared pretty low. Going down a hill in the lowest gear and pedaling as fast as my 59 year old legs could go, I hit 26+ mph according to my bike computer. I only ever use the 7 highest gears, and where I ride I never even have to stand up going up the long, but not too steep hills. When I wear out the sprockets and chain, maybe I'll go to different gearing for some more speed.
i think you might have your hi/lo gearing mixed up; just like on a motor vehicle, lo gears to go up hill, high gears coming down.
nonetheless, don't expect to see as high a speed descending on a MTB as you would on a proper road bike; the fatter/chunkier tires, flat bar and upright riding position are all working against you in wind and rolling resistance.
much to the chagrin o' many a squid, on a good road-racing bike on a steep twisty descent, i'm likely to be able to keep up with and pass sport motos, mostly due to the ability to brake harder and later before turns. knowing this always spooks me when i'm working Moto Ham at an event, since i'm fully aware of how fast a road bike can actually corner, and how hard it actually is to stay out of the way.