Originally Posted by dscheidt

When it was on kreuzotter.de, there were a whole bunch of citations, to people who had wind tunnels and had written about it. You're probably overestimating the windspeed your riding in, underestimating the slope of what you think are flat sections, and neglecting to consider time spent accelerating. (All are very common, and hard to measure without instruments.) Weight matters not a whole lot to maintaining a constant speed on level ground; the weight term gets swamped by air drag at 15 or so mph. it matters a great deal when you try and accelerate it, which Kruezotter doesn't consider. (and just a couple stops can kill average speed.) and even tiny hills change power output amazingly. A 0.5% grade -- six inches in a one hundred feet, 26 feet in a mile, an angle of 0.29 degrees -- is enough to make you work harder on it.