Box Two External Sealed 30mm Bottom Bracket

Product Overview

The Box Two External Sealed 30mm Bottom Bracket is a sealed cartridge system designed specifically for Box One M30-M and Box Two M30-P cranks. Built from 6061-T6 aluminum with sealed bearings, it resists contamination and extends service life in varied riding conditions. The 30mm axle diameter provides the stiffness required for responsive pedaling feel.

Key Features

• External sealed cartridge design — Bearing cartridge sits outside the shell, protecting internals from dirt, mud, and water while allowing straightforward bearing replacement
• Sealed bearings — Reduces maintenance intervals and prevents premature wear from moisture and abrasives
• 6061-T6 aluminum construction — Offers a balance of weight and durability with proven resistance to repeated impacts
• 30mm axle diameter — Larger diameter increases lateral stiffness compared to smaller axles, reducing flex under load
• BSA threading — Standard 1.37" x 24 TPI thread pattern ensures compatibility with most BMX frames

Technical Specifications

• Weight: 110 grams (3.9 ounces)
• Material: 6061-T6 aluminum
• Shell width: 68mm
• Thread standard: 1.37" x 24 TPI (BSA)
• Axle diameter: 30mm
• Bearing type: Sealed cartridge
• Crank compatibility: Box One M30-M and Box Two M30-P only

Compatibility and Ideal Use Cases

This bottom bracket is exclusive to Box One M30-M and Box Two M30-P cranksets and will not work with other manufacturers' cranks. Ideal for riders upgrading from worn original hardware or building a complete drivetrain with Box components. Recommended for street, park, and racing applications where sealed protection against weather and dirt is valuable.