a me sembra che siano strato esterno 3k o UD e interno sempre UD
per cui si spiegherebbe il peso minore degli UD
qua scrivono che UD è più leggero del 3k
For the weight difference, woven fiber has some area pass across each other. So, woven fiber is heavier than UD fiber. But, for rims, the size of carbon fiber is not large and only one layer different, the weight difference of woven fiber (3k &12k) and UD fiber is not big. Also, all rims have a weight range, for rims, it is +/-15g. So, sometimes, 3k rims & frames are lighter than UD.