SRAM RED E1 1x 172x50 AERO DUB NoBB CARBONUltra light hollow carbon fiber crankarms are 29 g lighter than previous generation X SYNC wide tooth, narrow tooth chainring technology provides maximum chain control Single ring drivetrain simplifies functionality and reduces weight Direct mount aero chainrings for better aerodynamics DUB bottom bracket adds durability and simplicity Can be upgraded to a power meter