Threadless Stem Shim Adapter 1” to 1-1/8” - Bicycle Fork Steerer Tube Reducer - 2 Piece Set

This 1” to 1-1/8” headset shim set allows a standard 25.4mm (1”) fork steerer to be used with modern 28.6mm (1-1/8”) headset and stem systems. It creates a precise, centered fit that removes play and ensures proper stem alignment for stable handling on custom and motorized bike builds.

It is commonly used to run standard 1” forks on bikes like the Zeda Screaming Demon and Zeda Dawn, making it possible to mix classic fork setups with modern headset standards without replacing your entire front end.

The system uses a two-piece design. The main sleeve fills the head tube interface and centers the 1” steerer inside the 1-1/8” setup, while the spacer ring installs above it to fine-tune stack height and improve stem clamping surface for a secure cockpit setup.

Together, these components form a complete reduction system that allows a 1” fork to be safely run in a 1-1/8” headset without modification, keeping the front end tight, aligned, and properly supported under load.

Specifications:

• Fork Steerer Compatibility: 25.4mm (1”)
• Headset / Stem Compatibility: 28.6mm (1-1/8”)
• System Type: Two-piece reducer (sleeve + spacer ring)
• Sleeve Length: 29mm
• Spacer Thickness: 5mm
• Function: Centers steerer and adapts diameter for proper headset/stem fitment
• Application: Motorized bikes and custom bicycle fork/headset conversions