See how to assemble the Manual interface (MHI) on a wheel with a 135mm solid axle hub.

Backward compatibility

This guide is compatible with legacy enviolo and NuVinci 135mm solid axle hubs.

Spline nut compatibility

There are 2 variants of the Manual hub interface (MHI) with different spline nuts (A) – 40T and 44T.

Their compatibility with Enviolo hubs depends on the year of the hub. Since 2025, we commmonized all hubs with 40T, but some older hubs have 44T splines:

2025

• Hubs with 40T – All hubs are commonized with 40T.
• Hubs with 44T – Discontinued.

2024 and earlier

• Hubs with 40T
  • 148mm modular axle – All modular hubs.
  • 135mm solid axle - Heavy Duty, Extreme, Extreme Gearbox, CA.
• Hubs with 44T
  • 135mm solid axle - Urban, City, Trekking, CO, SP, CA.

Step-by-step instructions

Video

Tools

• Torque wrench
• 17mm long socket
• Marker pen (white)
• Vice

Assembly instructions

1. Make sure the Manual hub interface you have has the correct amount of spline nut teeth for your hub:
   • The Urban, City, and Trekking hubs are compatible with 44T.
   • The Heavy Duty and Extreme hubs are compatible with 40T.
2. Clamp the wheel on a vice with the left-side axle flats.
   
3. Position the uninstalled Manual hub interface behind the dropout and determine the desired orientation before assembly:
   • Typical orientation is forward, parallel to the chainstay, or via the seat stay cable routing.
   • Cables should not bend too much.
4. Mark the interface in the middle of the dropout using a marker pen.
    
   • With the interface oriented correctly inside the right dropout, the installation angle is the indicated angle of the dropout.
     
   • This marking on the hub interface will help determine the angle during assembly.
5. Make sure the Manual hub interface is rotated counterclockwise, to full overdrive position (H).
6. Remove the anti-shift retainer if one is installed on the hub.
   • The anti-shift retainer comes typically installed on new hubs.
     
   • If an anti-shift retainer is not installed, then make sure that the markings between the spline nut (C) and the shift driver (D) are aligned. If the marking are not aligned, you will need to reset the hub to full overdrive before proceeding.
     
7. Hold the Manual hub interface over the right-hand axle, and looking at the marking you did earlier with a pen, align that marking with one of the the axle flats.
8. When aligned, seat the Manual hub interface fully onto the axle, onto the shift driver and spline nut.
   • Remember that the spline nut (C) and shift driver (D) markings must also be aligned, and the Manual hub interface must be in full overdrive (H).
9. Thread the right-hand 17mm nut, serrations facing outward, onto the axle.
   • Tighten it to 8-10Nm.

Next: assemble the wheel into the frame

If you follow the steps above, you should have a rear wheel with a Manual Hub interface assembled. The next would be to assemble the wheel into the bike frame. Proceed to this guide:

• How to assemble a Manual-equipped rear wheel on a 135mm solid axle frame

Done

If you have any questions, please don't hesitate to contact enviolo Support.