On 7/15/2018 3:00 PM, Frank Krygowski wrote:

I might point someone to the book _Bicycling Science_ by Wilson.

All things being equal, on typical road surfaces, a larger diameter
wheel should roll easier. But for slight differences in diameter, I'd
expect the differences in rolling resistance to be slight.

...


Among the recumbent riders, it is pretty well known that taller tires do
roll easier, since there have been various models of recumbent bikes
that could be ordered with 20", 24", 26" and 700c tires, but that were
otherwise roughly equivalent.

The larger tire diameter is mainly an advantage on bumpy surfaces
however. And at higher speeds, aero drag becomes a factor.

Some of the Battle Mountain bikes have gone to using front & rear 406mm
(20") wheels. Not for rolling resistance, but because the smaller wheels
can be contained inside a smaller body shell--and at ~80 mph, aero drag
is the biggest problem.