e*thirteen Helix Race e*spec Direct Mount Chainring for Bosch CX/SX - 34T, 13mm Offset, Bronze

The e*thirteen Helix Race e*spec Direct Mount Chainring merges cutting-edge engineering with a refined technical aesthetic, delivering the ultimate drivetrain performance upgrade for modern electric mountain bikes (e-MTBs). Forged and precision CNC-machined from premium 7075-T6 aluminum, this one-piece direct mount chainring is purpose-built to handle the high-torque loads of aggressive e-bike riding. When paired with Helix Race Alloy e*spec crank arms, it creates a clean, fully integrated look that significantly enhances both the strength and style of your motor system assembly.

This Bosch-specific version features a 13mm offset, meticulously calculated to deliver precise, friction-free chainline optimization depending on your specific Bosch motor generation. For Bosch CX Gen 4 and lightweight Bosch SX motor systems, it yields an agile 53mm chainline. When mounted to the latest high-performance Bosch CX Gen 5 motors, it transitions perfectly to a wider 55mm chainline. This accurate offset prevents premature drivetrain wear, minimizes friction, and guarantees smooth shifting performance across the entire gear range of wide-ratio cassettes.

Drivetrain security is managed by e*thirteen's updated M4 narrow-wide tooth profile. This advanced long-wearing shape features enhanced tooth geometry that locks the chain securely in place over punishing, high-speed trail chatter, eliminating the absolute need for a heavy chain guide. Furthermore, the M4 profile offers comprehensive cross-compatibility with Shimano, SRAM, and TRP 11 and 12-speed drivetrains—including seamless operation on premium SRAM T-Type Transmission systems, allowing you to run your preferred shifter and cassette setup without compromise.

Weighing a competitive 107g, this 34T chainring provides a slightly larger gear step for riders looking to maximize top-end speed and raw power output on fast, flowing trail descents. The one-piece design balances weight-saving performance with structural stiffness to prevent flexing under hard, out-of-the-saddle efforts. Finished in a durable, standout bronze anodized coating that protects the alloy against rock-strike abrasions and elements, it delivers maximum wear life and a premium custom look. The Helix Race e*spec chainring is compatible with all matching Bosch direct mount motor systems and is backed by e*thirteen's dependable 5-year manufacturer warranty.

Key Features

• Forged & CNC-Machined 7075-T6 Aluminum: One-piece construction delivers maximum structural stiffness, high wear life, and premium impact resistance


• M4 Narrow-Wide Profile: Advanced tooth geometry offers bulletproof chain retention across brutal trail chatter and eliminates chain drop


• Universal Drivetrain Compatibility: Engineered to run seamlessly with Shimano, SRAM, and TRP 11/12-speed systems, including SRAM T-Type Transmission


• Bosch Direct Mount Integration: Designed specifically for clean integration with Bosch CX Gen 4, Bosch CX Gen 5, and Bosch SX motor splines


• Optimized Drivetrain Chainline: 13mm offset achieves a 53mm chainline on CX Gen 4 / SX systems, and a 55mm chainline on CX Gen 5 platforms


• Premium Bronze Anodized Finish: Provides long-lasting resistance against trail abrasions while giving your motor setup a distinct visual identity

Specifications

• Model: e*thirteen Helix Race e*spec Direct Mount Chainring


• Tooth Count: 34T


• Motor Compatibility: Bosch CX Gen 4, Bosch CX Gen 5, Bosch SX


• Offset: 13mm (Measured precisely as 13.5mm offset architecture)


• Chainline Realization: CX Gen 4 / SX: 53mm | CX Gen 5: 55mm


• Drivetrain Compatibility: Shimano / SRAM / TRP 11-Speed & 12-Speed (Including SRAM T-Type)


• Tooth Profile: M4 Narrow-Wide


• Material: Forged and CNC-Machined AL-7075-T6 Aluminum


• Weight: 107g


• Color: Bronze


• Warranty: 5 Years

A premium, high-stiffness direct mount chainring built for aggressive e-MTB riders who demand zero chain drops, precise chainline tracking, and unique custom style on high-torque Bosch motor systems.