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Altias Stem — Argon18

Altias Stem — Argon18

Regular price $450.00 NZD
Regular price Sale price $450.00 NZD
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Developed in collaboration with Aus Cycling and Cycling Canada for the Paris Olympic Games.

Optimised stiffness-to-weight ratio to achieve the best possible direct mount cockpit under high-intensity accelerations. Furthermore, an in-depth aerodynamic study was undertaken to ensure airflow around the leading edge of the stem and headtube junction maintained a fluid and attached airflow.

Note: Direct mount screws are sold separately. please refer to the user manual below to identify your screw length requirements.


Please view the Velobike Longboi Stem - Argon18 User Manual & Geometry Guide for selecting the correct stem size for your requirements.

Velobike Argon18 Longboi Stem User manual

The user manual includes:

  • Reach and stack dimensions
  • Handlebar reach limits (to 100mm in front of the axle)
  • Stem weights
  • Direct mount bolt length requirements 
  • Installation instructions
  • Installation torque specifications
  • Spacer heights and their effect on reach and stack dimensions


  • Compatible with the Argon18 Electron Pro (Rio and TKO) Sprint and Pursuit Framesets
  • ISO 4210-5:2014 certified (tested to 2x the ISO requirements)
  • Aero design developed using CFD software
  • Bar clamp diameter: 31.8mm

  • Bar clamp width: 49mm

  • Recommended to use copper grease on screw threads (grease not included)
  • Direct-mount screws are sold separately


  • 1x Stem (of selected size)
  • 1x Faceplate
  • 4x Faceplate screws

Optional Extras:

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