Originally Posted by SquidPuppet

Look at aeronautics. Shape and surface texture are far more important than actual size.

Notice that the threading on a valve closely resembles the fins of an automobile radiator? What is the purpose of an automobile's radiator fins? To catch air.

Bikes with no valve caps are suffering extreme aero penalties, and therefore experiencing significant speed losses.

Again. Any serious cyclist worth his salt (should) understands the performance benefits of a light weight and efficiently shaped valve cap. There are a lot of folks out there with no real understanding of the actual physics involved. It's not their fault. They are neither engineers nor physicists. But don't allow yourself to be fooled by the naive and unsophisticated.