Northwave extreme xc mtb spd shoesthese extreme xc mtb shoes from northwave have hyperlight xc soles made of 100 unidirectional carbon with a stiffness index of 140 for top power transfer they are 28 more abrasion resistant than tpu and the michelin rubber inserts with dual layer compound technology provide excellent grip with minimum weight while the micro perforated biomap unibody uppers with thermowelded protection eliminates hotspots the integrated heel system contains directional fibre t