Originally Posted by cyccommute
Here's the other issue. I just using wild guess number here but I think I'm close. If you have a down tube that is 3" I.D. and that is 30" long that will give you around 90 cu. in. of air. A 1" tire on a 700C rim has a volume of around 70 cu. in. Not a problem so far because for one tire to get the pressure to 125 psi, you'll need just about the equivalent volume. But, for 2 tires, you are going to need to put double the volume in the same space and the only way to do that is to put in twice the pressure. Now you need 250 psi in 92 cu. in. of the downtube.
Even more! You'd need 150% of that amount, since no air will flow from downtube to tire once the pressures are equal. 375 psi. Then there's the issue of obtaining that pressure in the first place.
And, once you've gone to all that trouble, this kind of pressure has much more interesting applications than inflating tires. Like pneumatic driver education devices! What would an Airzound sound like at 375 psi? Or maybe one of those American Gladiators turrets, with improved ammunition?