I have searched and this is my first post so forgive me if this has been beaten to death elsewhere: I know there are 3 differences (chainring treatment, chainring bolts, incompressible foam remains in chorus) but I have no understanding of the carbon layup differences between the two cranks? My understanding is that the completely different layup of the Record crank gives rise to a higher strength to weight ratio relative to the Chorus but I'd like to know how that conclusion is reached and whether there's an appreciable performance difference (since the weight difference is ~ 40 grams). I have read that the difference is analogous to the layup differences in Campy '05 and '06 which did quantifiably increase lateral stiffness. Any help out there from someone who can 'splain it to me Lucy?