I wouldn't want to take Jur on. While there is no real performance difference by wheel size, anyone who can win a time trail UPHILL on a heavy R20 with a hub gear gets my immediate concession.

The only advantage he had on that ride was the small wheels, which have less moment, thus climb better.

By the way, here is some info on the small wheel performance issue: http://www.alexmoulton.co.uk/frames.asp?id=questions

This seems to be the collective opinion in the forum on this:

Small wheels: less air to displace at any given pressure (PV = nRT), but the smaller contact patch can create more tire deformation under smooth conditions and lower pressures. Less wind resistance (which is significant given fewer spokes and shorter spokes than an equivalent 700cc wheel). Less ability to absorb shock (and thus slower on rough surfaces) than bigger tires. More hub resistance, which plays a tiny role. Less moment: better able to get out of tough situations in traffic and great on uphills, but bad on downhills. Less total rolling resistance on tests biased against small wheels (small diameter drums with or without a smooth surface) at high pressures and lower wind resistance makes them ideal on smooth surfaces and uphills.

Big wheels: a more comfortable ride on rough surfaces, more moment and thus more stability and speed downhill, better tire selection. Bad on climbs, but this is more than compensated for by the lighter road bike to which it is attached. I've never seen anyone provide documentation that big wheels are more efficient, but tons providing documentation that small wheels are more efficient. This is probably more due to big wheel advocates never testing the theory.

I think it's funny that people will try to make head-on-head comparisons using average speeds on one trial. A power meter is really needed. But a collection of many average speed reports over a large number of trials, conditions, and riders on identical tires and similar bike will support (but not likely reject) rough equivalency, the null hypothesis. We tried that here, but it didn't go anywhere. Psychological factors play a huge role as well, so any test will be biased unless it is mechanized.

A suspended small wheel is great for most applications, and may well be faster than an unsuspended large wheel on roads. But when I hit deep dust powder, pesky rocks, or ruts on descents, I'm less happy with my suspended small wheels. My back tire lock broke on the last flight, so I'm unable to do bunny hops, which makes off road riding even more problematic.