Shimano Alivio FD-M3120-M-B Front Derailleur

The Shimano Alivio FD-M3120-M-B is a highly efficient 2x9-speed mountain bike front derailleur that utilizes Shimano's innovative Side Swing design. This "M-B" variant features a middle clamp band mount (Mid Clamp) and comes as a full set, including sizing shims to adapt to frame seat tubes measuring 28.6mm, 31.8mm, or 34.9mm.

Technical Specifications

• Drivetrain Compatibility:
  Designed for 2x9-speed mountain bike groupsets (Shimano Alivio series).
• Mounting Type:
  Mid Clamp / Clamp Band, with adapters included for 28.6mm and 31.8mm onto a 34.9mm base.
• Linkage Action:
  Side Swing design, where the linkage moves horizontally outward rather than pivoting vertically.
• Cable Routing:
  Front Pull – the shift cable enters directly from the front of the frame's down tube.
• Chainline:
  51.8mm, optimized for standard and wider mountain bike hub spacings.
• Maximum Low/Top Gear:
  Optimized for a 36 Teeth maximum large chainring. The ideal setup is a 36-22T double chainring.
• Total Capacity:
  14 Teeth – the maximum allowable tooth size variance between your small and large front chainrings.
• Chainstay Angle:
  Compatible with chainstay angles between 64–69 degrees.

This derailleur is a reliable choice for mountain biking enthusiasts, offering precision, adaptability, and compatibility with modern 2x9-speed systems.