Box One Chain Tensioners 2020 Edition

Product Overview

Box One Chain Tensioners are CNC-machined dropout inserts designed to secure rear wheel positioning and protect frame dropouts from wear. Extruded from 7075 aluminum and precision-machined for minimal weight, they provide adjustable wheel placement with laser-etched position guides. Features dual 10mm mounting holes for compatibility with most BMX frames.

Key Features

• 7075-T6 aluminum construction – Higher-strength aluminum alloy compared to standard 6061 provides increased durability in high-load dropout applications while maintaining low weight

• CNC-machined from extrusions – Precision machining ensures consistent fit and smooth surfaces for accurate wheel alignment and secure axle retention

• Laser-etched position guides – Permanent markings on tensioner body allow repeatable wheel placement for consistent chain tension after wheel removal

• Dual 10mm mounting holes – Two axle positions provide adjustment range to accommodate different chain lengths and dropout spacing variations

• Dropout protection – Tensioners distribute axle clamping force across a larger surface area, reducing frame dropout wear from repeated wheel installation

Technical Specifications

• Weight: 62 g (2.2 oz per pair)
• Material: 7075-T6 aluminum
• Axle compatibility: 10mm
• Mounting holes: 2 per tensioner (10mm diameter)
• Finish: Anodized with laser-etched graphics

Compatibility and Ideal Use Cases

Designed for BMX frames with horizontal or semi-horizontal dropouts using 10mm axles. Works with both cassette and freewheel drivetrains where chain tension adjustment is required. Best suited for single-speed setups where wheel position must be adjusted to maintain proper chain tension. Laser-etched guides help riders achieve consistent wheel alignment, particularly useful when swapping wheels or adjusting gearing. Not compatible with vertical dropouts, thru-axle systems, or frames with integrated chain tensioners. Proper torque is critical—over-tightening can damage both tensioners and frame dropouts.

Note: US orders ship direct from manufacturer and may arrive separately from other items.