Box One X4 Carbon Fork — 20"

Overview

The Box One X4 is a 20" BMX fork engineered with carbon fiber legs and a reinforced aluminum steerer tube designed for larger-framed riders. The fork uses oversized construction—redistributing carbon fiber to high-stress areas in the legs and crown—to maximize steering stiffness and load capacity without excess weight.

Key Features

• High-modulus unidirectional carbon legs — Rigid under braking and turning; vacuum-molded for consistent layup and impact resistance
• 7075-T6 aluminum steerer tube — Lightweight yet strong; larger 1-1/8" diameter accommodates taller riders and provides secure headset interface
• Internal butterfly reinforcement — Wraps the steerer-to-crown junction, reducing stress concentration and improving durability during hard landings and tricks
• Cold-forged 10mm dropouts — Precisely shaped aluminum (6061-T6) for reliable axle seating and consistent wheel alignment
• 32mm offset — Geometry-optimized rake for responsive steering while maintaining frame compatibility

Technical Specifications

• Fork height: 20" (303mm axle to crown)
• Steerer tube: 1-1/8" straight, 7075-T6 aluminum, extruded and butted
• Legs: High-modulus unidirectional carbon fiber, vacuum-molded
• Dropouts: 10mm, cold-forged 6061-T6 aluminum
• Offset: 32mm
• Weight: 565g (19.9oz)
• Weight limit: 115kg (253 lbs) — EN 16054:2012 Category 2 standard

Compatibility & Ideal Use Cases

• Wheel size: 20" BMX wheel with 10mm axle conventional hubs
• Frame compatibility: 1-1/8" headset
• Best for: Larger-framed riders (5'10"+); street, park, and racing
• Ideal use: Riders seeking maximum stiffness and responsiveness with modern materials
• Not suitable for: Riders under 115kg should verify compliance with the weight standard before use