Originally Posted by
Carbonfiberboy
As noted in the article comments, November only measured the straight line drag on the spinning wheels. They did not measure the power necessary to rotate the wheel. My take: the usual thing with those wishing to prove a prejudged point.
http://www.echelonsports.com.au/down...poke-shape.pdf
I'll go back to this, because that's useless for showing the effects of spoke shape. It uses wheels with significant differences in rim design between ALL the wheels. No two wheels in that paper use the same rim. The closest is some specious claim that two of the rims have "similar shapes". I'm unimpressed.
There's no way anyone can claim anything about the impact of spoke shape on drag from that data.
Not only that, the power comparison in that paper is not simply how much energy it takes to spin a wheel - else there wouldn't be a "wind angle" in the plot of multiple wheels with power plotted against wind angle.
That paper is useless in determining the power savings from bladed spokes because every rim is different, and it's not even measuring the power needed to just spin the wheel, as has been claimed - merely spinning a stationary wheel means there's no wind and therefore no wind angle. But that paper's big reveal of data is a graph of power vs wind angle for a bunch of completely different wheels.
And you know what? That paper never once mentions the wind speed used in the test. Sure, it mentions that the wheels were spun at 30 mph. But what was the wind speed? What was the tire pressure? What were the tires used? Was the same tire used on every wheel?
If you want to measure the aerodynamic gains from bladed spokes, you control everything else - keep EVERYTHING ELSE identical - and change JUST THE SPOKES. Rims, tires, hubs. Everything the same. The only difference is the spokes.
And when that's done, the gain from bladed spokes is:
One watt.
Of course, wind tunnels have been around for over a century, and charge hundreds or thousands of dollars an hour. Lots of people have used them for some very expensive things in cycling alone. Nevermind the same aerodynamic folks also work in aerospace and automotive industries where the level of resources greatly exceeds that expended in cycling - but where cycling gets to benefit from all the work done in those other fields.
Armchair internet posters are going to notice something blindingly obvious - "THAT WHEEL IS SPINNING!!!", that an entire industry with over a century of deep and thoroughly reviewed and tested methods has missed?
Uh yeah, sure they will.
The same guys who do aerodynamics for motorcycle and top-fuel drag racing and Formula 1 and NASCAR and Indy car racing suddenly forget that the wheels are spinning when the object of the test is a bicycle?