I would like to simplify what I got out of the book review. Essentially, a
wheel is a moving body pushing through the air like any other object.
Whether it is rotating or not, as an object, it has a drag coefficient and
Area. What the review is saying is that, the CdA of an the object
contributes far greater to its TOTAL drag, rather than the fact that it is
rotating. John Burke's comment of a few percent (rotational drag) seams
quite plausible when you consider a wheel's Cd and trying to push a
flat-plate area of 1 or 2 square ft at speed. Always enjoy Mayf's "spin" on
things though. -Elon
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