SRAM DUB™ is the single replacement for 30mm and 24mm bottom bracket spindles options. They fit all frame shell standards and DUB™ does NOT introduce any new frame shell standards. DUB™ The relationship between bottom bracket spindle and bearing is the core of DUB™ technology. It’s where stiffness meets durability. We took it a step beyond conventional thinking and made everything simpler—better integrating the relationship between chainring, crank, spindle, and bottom bracket. It’s this approach to developing a complete system that equals better drivetrain performance.