Indeed, for those who are more math inclined the stiffness is calculated as a proportional to (D^4 - d^4) where D = outer diameter and d = inner diameter (and d = 0 if the bar is plain), while the weight is proportional to (D^2 - d^2).
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2017 M550i | Sophistograu
Previous cars: 2014 F30 ActiveHybrid 3 | 2012 f20 M135i
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