BOX ONE OVERSIZED SINGLE SPEED COG

Product Overview

The Box One Oversized Single Speed Cog is a CNC-machined chromoly steel cassette cog designed for BMX cassette hubs with oversized (OS) spline drivers. Featuring a 5mm-wide inner base and ED black finish, this cog provides a solid interface with the freehub body for efficient power transfer and extended durability. Compatible with both 3/32" and 1/8" chains, it suits a range of BMX racing drivetrain configurations.

Key Features

• Chromoly steel construction – CNC-machined from high-strength steel provides exceptional wear resistance and long service life under pedaling loads
• Oversized spline interface – Designed specifically for OS spline freehub bodies, including the Onyx Ultra SS Driver
• 5mm-wide base – Wider cog base increases contact area with the freehub body, improving load distribution and reducing freehub wear
• Dual chain compatibility – Works with both 3/32" (standard racing) and 1/8" (wider, more durable) chains
• ED black finish – Electrodeposition coating provides corrosion resistance and clean appearance
• Laser-etched graphics – Permanent laser-etched branding won't fade or peel over time

Technical Specifications

• Material: Chromoly steel, CNC-machined
• Finish: ED black with laser-etched graphics
• Spline type: Oversized (OS) spline
• Chain compatibility: 3/32" or 1/8"
• Available tooth counts and weights:
  • 14T: 20g (0.70 oz)
  • 15T: 28g (0.98 oz)
  • 16T: 36g (1.27 oz)
  • 17T: 38g (1.34 oz)
  • 18T: 42g (1.48 oz)
• Compatible drivers: Onyx Ultra SS Driver and other OS spline freehub bodies

Compatibility and Ideal Use Cases

This cog fits only BMX cassette hubs with oversized (OS) spline freehub bodies—NOT standard Shimano spline or other spline patterns. Verify your hub uses OS spline before ordering. The Onyx Ultra SS Driver is specifically mentioned as compatible. Works with both 3/32" chains (lighter, standard for racing) and 1/8" chains (more durable, common on street and park setups).

Best suited for BMX racers using OS spline hubs who want maximum durability and efficient power transfer. The chromoly steel construction resists wear from chain engagement far better than aluminum cogs, making this ideal for riders who put high torque through the drivetrain or ride frequently. The 5mm-wide base distributes pedaling forces across a larger freehub surface, reducing the likelihood of damaging the freehub splines. Choose tooth count based on gearing preference and track requirements—smaller cogs (14T-15T) for higher gearing and top speed, larger cogs (17T-18T) for easier acceleration and lower gearing. The dual chain compatibility allows flexibility in drivetrain setup. Not compatible with standard Shimano-spline hubs—attempting to install this cog on a Shimano spline driver will not work.