There's a time and place for carbon crank arms; however, it might not be the time you get too ambitious with a bunny hop and crack one open on a barrier. Rotor's 3D30 CX1 Crank Arms are right at home there, though, with an aluminum construction that's artfully machined to shed grams without losing any of alloy's stiff reliability--proving why come autumn, even the most carbon-obsessed roadie will hop on alloy cranks for 'cross. The aluminum 3D30 CX1 crank may not be as light as carbon models, but those extra grams are peanuts compared to the added weight from the beer hand-ups you take throughout the season. The other heavily touted benefit of carbon vs aluminum--stiffness--was rendered moot the first time we rode the 3D30 CX1 out of a sand pit in anger. They may in fact be more flexible, but we couldn't tell the difference. The crank arms owe their combination of low weight and high stiffness to Rotor's proprietary CNC-machining process, Trinity Drilling System. It involves mapping and removing as much material as possible without compromising the crank arms' structural integrity or stiffness. Maybe Rotor could've shaved off more weight, but we're assuming restraint won out because--like us--those crafty Spaniards were unwilling to make sacrifices in how the crank feels under the pedal stroke in order to score points on the scale. To which we say gracias.