The white wheel pant is Van's 2-piece "pressure recovery" wheel pant. The wheel pant on the left is from Sam James.

Looking down on the Sam James wheel pant.

Looking down on the Van's wheel pant.

The front end of the Sam James Wheel Pant

The front end of the Van's wheel pant.

This really shows the difference in shapes. Who knows which one is faster. I'm sure each manufacturer says his is faster. The Sam James pants sure feel lighter. I haven't weighed them, but subjectively, there's a difference.

Here is the wheelpant loosely assembled with the Cheng Shin tire and wheel assembly sitting in front of it. You can see that with both the pant and the tire sitting on the ground, the tire is just slightly taller than the wheelpant. You can see that the tire is approximately 11-1/2" tall.

I've raised the pant to approximately the correct height above the top of the tire. I don't have the instructions from Sam James in front of me right now, but I think they suggest allowing about 5/8's of an inch above the tire for clearance. Seems reasonable. Just ball-parking it, it looks like the bottom of the pant should come to approximately the bottom of the rim.