&gt; for almost all riders the real killer is rolling resistance<p>Aerodynamic resistance becomes greater than rolling resistance very early. See eg. <a href="http:&#x2F;&#x2F;www.sheldonbrown.com&#x2F;rinard&#x2F;aero&#x2F;formulas.htm" rel="nofollow">http:&#x2F;&#x2F;www.sheldonbrown.com&#x2F;rinard&#x2F;aero&#x2F;formulas.htm</a><p>You may argue that people riding upright on city (&quot;dutch&quot;) bikes make up the majority of bike riders, but their possibly heavy-rolling tires are made up for their aerodynamically pessimal riding posture!<p>(Of course often it&#x27;s easier to do something about rolling resistance than aerodynamics, despite being a smaller component)