The surprise came when he looked more closely at the higher bending (flexural) modes: in that case, the frequency increased at higher loads. “The bar becomes more fixed so the actual wavelength of the bar is less,” Langlois explained. “With a set wave speed, wavelength is inversely proportional to the rate of oscillation, so we get a higher frequency. This is something we did not foresee happening. So the barbell is likely to matter.”
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Precisely which features make for the best barbell is still a puzzle. Olympic barbells have the same weight, diameter, and length, but other aspects can differ from brand to brand, such as the materials used. Most are made of some sort of steel, with stainless and chrome-coated being the most common, and the respective mechanical properties can make a small difference to a given bar’s whip, according to Langlois. Specifically, the stiffness of the bar (the Young’s modulus) can vary quite a bit. “We don’t have a good feel for this because no barbell manufacturers will tell you exactly how they make the bar,” he said. “It’s all proprietary.”