RaceFace Next SL Crank Arms The crank arms are completely hollow with all unnecessary material being removed from the center core - no internal aluminum spine Industry standard 30mm spline interface CNC machined from an aluminum that is 20% stronger than 7050 alloy (commonly used in this application) Removable spider (sold separately) offers the ability to convert between existing chaining standards while remaining flexible to future developments Weight: 535g (22/36T, 24/36T), 540g (24/38T) Direct mount single chaining option (sold separately)