BOX ONE OVERSIZED 31.8mm DELTA STEM 1-1/8"

Product Overview

The Box One Oversized Delta Stem is a forged and CNC-machined 6061-T6 aluminum stem designed for 31.8mm handlebars and 1-1/8" steerer tubes. Featuring a 45-degree load clamp design with side skirts, massive bar bore, and chromoly clamping bolts, it's engineered for maximum rigidity and power transfer. Available in 48mm and 53mm reach options with 0-degree rise and meets EN 16054 Category 2 standards.

Key Features

• Forged and CNC-machined 6061-T6 aluminum – Forging process increases material density and strength before machining, creating a stiffer stem with optimized material placement
• 45-degree load clamp with side skirts – Angled clamp design with structural side walls increases rigidity and reduces flex during hard pedaling and pulling on the bars
• Oversized bar bore and interface – Increased clamping surface area matches the thicker wall and larger diameter section of oversized handlebars, minimizing twist and improving responsiveness
• Massive chromoly clamping bolts – Larger, stronger bolts provide secure clamping force and prevent slippage under high loads
• Reverse-engineered structure (outside-in design) – Stem design starts with the outer profile and works inward, optimizing material placement for larger riders who generate higher forces
• Two-tone anodized finish with laser-etched graphics – Durable anodized coating with permanent laser graphics resists wear and maintains appearance
• EN 16054 Category 2 certified – Meets European safety standards for BMX and dirt jumping use

Technical Specifications

• Material: 6061-T6 aluminum (forged and CNC-machined)
• Hardware: Chromoly clamping bolts
• Finish: Anodized with laser-etched graphics
• Clamping Type: 45-degree load (top load style)
• Steerer Tube Diameter: 1-1/8"
• Handlebar Clamp Diameter: 31.8mm (oversized)
• Rise: 0°
• Stack Height: 32mm
• Reach Options: 48mm, 53mm
• Weight: 290g (48mm), 299g (53mm)
• Safety Standard: EN 16054 Category 2

Compatibility and Ideal Use Cases

This stem is compatible with 1-1/8" threadless steerer tubes and 31.8mm oversized handlebars only. Not compatible with standard 22.2mm handlebars, 25.4mm bars, or 1.5"/tapered steerer tubes. Works with integrated, semi-integrated, and external cup headsets that accept 1-1/8" steerer tubes. Ideal for larger, more powerful riders who need maximum stiffness and rigidity to prevent handlebar twist and stem flex during aggressive pedaling and pulling. The oversized interface design works best when combined with Box oversized handlebars to fully realize the stiffness and power transfer benefits. Choose reach based on rider size—48mm for closer hand positioning, 53mm for extended reach and stability. Note: Ships direct from manufacturer if located in the USA, which may result in separate delivery from other items.