Black series alloy cranks are directionally cnc machined from grain orientated 7075 t6 heat treated aluminium with a cnc machined spider in 7022 aluminium featuring a universal 4 bolt 10464 bcd double bolt circle diameter extremely low weight and high strength the integrated 30 mm diameter integrated hollow 7075 t6 heat treated aluminium axle fixed to the drive side arm is a key feature of the cranks design creating one of the torsionally stiffest systems on the market resulting in maximu