red axs aero cranksetTriathlon. Time Trial. Cyclocross. Some disciplines are made for 1x. And while our X Range 2x set up has integrated much of the simplicity of a 1x system, there are still times when a single ring is best. The SRAM RED 1 crankset offers the most demanding racers the right mix of featuresaerodynamics, durability and simplicity. Speeds. 12 BB Compatibility. All SRAM Road DUB BBs, GXP PF GXP 68mm Chainring Size. 40, 46, 48, 50 Crank arm length. 165mm,