Specialized 1-1/8 Star Nut Top Cap Assembly M6x35 OEM
Specialized 1-1/8 Star Nut Top Cap Assembly M6x35 OEM
Stage 21 Bikes
23582 Moulton Parkway
#111
Laguna Woods CA 92637
United States
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Specialized 1-1/8" Star-Nut & Top Cap Assembly
Factory OEM | Alloy Steerer Headset Preload Kit | S182500007
The Specialized Factory Replacement 1-1/8" Star-Nut & Top Cap Assembly is a genuine OEM headset preload kit for compatible bicycles using a standard 1-1/8" threadless alloy steerer tube.
The kit combines a six-flanged steel star-nut, lightweight concave alloy top cap, and long M6 × 1.0 × 35mm alloy preload bolt to provide the hardware required for headset installation, fork replacement, or service of worn original components.
Available from Stage 21 Bikes, your trusted source for hard-to-find Specialized OEM replacement parts.
Key Features
- Genuine Specialized factory OEM replacement assembly
- Designed for standard 1-1/8" threadless steerers
- Six-flanged steel star-nut
- Lightweight alloy top cap
- Concave, low-profile top cap design
- M6 × 1.0 × 35mm alloy preload bolt
- 4mm hex tool interface
- Suitable for headset service and fork installation
- Specialized MPN S182500007
Kit Includes
- 1 × 1-1/8" Six-Flanged Steel Star-Nut
- 1 × Concave Alloy Top Cap
- 1 × M6 × 1.0 × 35mm Alloy Top Cap Bolt
Specifications
| Specification | Details |
|---|---|
| Brand | Specialized |
| Component | Star-Nut & Top Cap Assembly |
| Steerer Size | 1-1/8" |
| Steerer Type | Threadless |
| Star-Nut Material | Steel |
| Star-Nut Design | Six-Flanged |
| Top Cap Material | Alloy |
| Top Cap Shape | Concave |
| Bolt Thread | M6 × 1.0 |
| Bolt Length | 35mm |
| Bolt Material | Alloy |
| Tool Interface | 4mm Allen / Hex |
| MPN | S182500007 |
Recommended Applications
Suitable for compatible bicycles using a 1-1/8" alloy threadless steerer, including appropriate:
- Road bikes
- Gravel bikes
- Mountain bikes
- Replacement fork installations
- Headset service and rebuilds
- Replacement of damaged or corroded preload hardware
Installation Notes
- The star-nut is installed inside the steerer and provides the anchor point for the headset preload bolt.
- Use a proper star-nut installation tool to position the star-nut correctly within the steerer.
- The top-cap bolt is used to establish headset bearing preload before the stem steerer-clamp bolts are tightened.
- The top-cap bolt is not intended to secure the stem by itself.
- Adjust headset preload and stem hardware according to the applicable bicycle and component service specifications.
Important Carbon Steerer Warning
Do not install a star-nut in a carbon steerer tube.
Star-nuts are intended for compatible metal/alloy steerers. Carbon steerers require an appropriate compression / expansion plug designed for carbon construction.
Compatibility Notes
- Requires a standard 1-1/8" threadless steerer.
- Intended for compatible alloy or other manufacturer-approved metal steerer tubes.
- Not appropriate for carbon steerers.
- Verify steerer dimensions and Specialized MPN S182500007 before ordering.
- This listing includes the star-nut, top cap, and preload bolt only.
Factory-Correct Headset Preload Hardware
A properly installed star-nut and top-cap assembly allows the headset bearings to be preloaded correctly before the stem is secured to the steerer.
Genuine Specialized S182500007 combines the correct 1-1/8" six-flange star-nut, lightweight alloy top cap, and M6 × 35mm preload bolt in one factory replacement assembly.
Stage 21 Bikes carries genuine Specialized factory replacement parts and hard-to-find OEM service components for road, gravel, mountain, and Turbo bicycles.