Originally Posted by JavaMan

Yeah, I think you're right. During the TDF commercials, I have been sticking small objects between my rear tire and the roller on my trainer while slowly turning the tire. (What some people will do for fun ) The best object so far is an airsoft BB with a couple of flats filed on opposite sides. If I get it just right, it shoots out the side at high velocity, even though I am barely turning the wheel. This observation makes me absolutely sure that it's the tire pressure that governs the velocity. I wish I could measure the angle and distance, but it always hits the side of the flywheel. Since it hits, The angle must be less than about 45 degrees. I would love to plot the distance vs tire pressure.