The Box Extremum Race Prep External Bottom Bracket is specifically designed for BMX racing. Since BMX racers are not splashing through mud like mountain bikers they do not need the same level of bearing protection. Since bearing protection equals more friction, Box has created a bottom bracket that uses non-contact, titanium-coated SUS bearings, modified low-friction seals, and lightweight lube. Why titanium? More corrosion resistance, and more importantly, a lower coefficient of friction. This bottom bracket will leave you with cranks that are more free-spinning AND with a bottom bracket built to last in today’s BMX environment.
FEATURES
- High-Impact Anodizing
- 24mm Outboard Bearings
- Speed Grease
- Low Friction Seals
- Titanium-Coated SUS Bearings
SPECIFICATIONS
- COMPATIBILITY: Box Threeâ„¢, Box Fourâ„¢, Shimano HollowTech II, RaceFace X-Type
- SHELL WIDTH: 68/73mm
- SPINDLE TYPE: 24mm
- THREAD: 1.37″ x 24 TPI
- WEIGHT: 100 grams / 3.52 ounces













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