Bonus: Berd's co-founder on the performance cost of vibrations
Summary
Bird founder and chemical engineer Brad Girton discusses a new white paper arguing that vibration damping is a critical, previously overlooked metric in off-road cycling performance modeling. He explains how Bird's viscoelastic Dyneema spokes reduce high-frequency chatter, distinct from suspension's impact reduction, to lower rolling resistance on rough terrain. The episode covers the physics behind these "intrinsic variables" and quantifies the performance gains, noting that Bird's spokes can save up to 5 watts on gravel by damping vibrations, a benefit comparable to choosing a wider tire …
Topics discussed
Intro: Bird's white paper on gravel wheels and vibration damping
Charlie Spang's background and the origin of Bird
From spokes to wheels: The rise of Bird in mountain biking
Olympic success and the 'smoothness' factor in performance
The new Sparrow 50 Gold gravel wheel release
The six components of cyclist power in performance modeling
Why Bird published full equations and data in their white paper
Challenges of modeling off-road versus on-road performance
Defining vibration and impact reduction coefficients
Intrinsic vs extrinsic variables and classifying suspension components
Quantifying the power penalty of rough surfaces and Bird's savings
Explaining viscoelasticity: Stiffness vs damping properties
The difficulty of measuring vibration damping on real bikes
Outro and membership promotion
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