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Behold The Hyundai Uni Wheel. Transportation May Never Be The Same
(cleantechnica.com)
This is a most excellent place for technology news and articles.
That was my thought as well. The pinion gear linkage looks comparatively fragile with its smaller gears and levers. Smacking a deep pothole at speed would likely cause the pinion gear to smack against the wheel, which wouldn't be good.