This SD Components bottom bracket is specially designed for BMX racing. It allows you to install a crankset with a 24 mm axle on a frame with an external width of 68 mm and an internal diameter of 42 mm. The SD bottom bracket offers both rigidity and practicality. Thanks to its threaded fitting system, it can be installed without a press, simply by screwing the two bearings together using a specific Shimano-type wrench. Quick, efficient and rigid are the words that perfectly describe this SD bottom bracket from Components. Technical specifications:- Material/Design: Aluminium - 100% CNC machined - Bottom bracket type: BB30SH TO 24mm - Internal diameter for axle: 24mm- External width (frame): 68mm - Internal diameter (frame): 42mm - Resized bearings for 24mm bottom bracket axle - Threaded installation system for easy press-free mounting- Clamping type: Standard Shimano - Double lip seals for a secure fit in the frame - Three spacers included to adjust the Q-factor and your chain line - Weight: 123g