FSA Compressor
FSA

FSA Compressor

In Stock

FSA Compressor expander bolt secures headset preload on 1 1/8" (28.6mm) carbon steerers. At just 33g with an anodized finish, it replaces a star nut for safer carbon-compatible clamping.

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Product Details

Overview & Technology

FSA's Compressor expander is a purpose-built top-cap expander for 1 1/8" (28.6mm) carbon steerers (Manufacturer Part #: 160-3010). It replaces the traditional star nut with a reversible, clamp-style wedge that anchors inside the steerer without crushing delicate carbon fibres. The complete assembly weighs just 33g, making it an unobtrusive, lightweight solution for modern road builds. The expander features a precision-machined, anodized aluminium body paired with a corrosion-resistant stainless steel bolt. That construction gives you the strength and bite needed to preload the headset while preserving the integrity of carbon steerers—ideal for riders who want secure steering and a clean, serviceable headset top-cap setup.

Key Features

Purpose-designed for carbon steerers: Unlike star nuts that rely on sharp teeth, this expander uses an internal wedge to secure itself to the inside of the carbon tube, greatly reducing the risk of steerer damage. The black anodized finish blends discreetly with most bars and headsets. • Lightweight: 33g total weight keeps your cockpit light. • Durable materials: anodized aluminium body with stainless steel bolt for long-term reliability. • Easy service: removable without destructive extraction inside the steerer.

Fit & Compatibility

This Compressor is specifically sized for 1 1/8" / 28.6mm steerers. It works with most 1 1/8" integrated and semi-integrated headsets where a carbon-friendly expander is required. Note that this listing is for the expander/bolt assembly; a separate top cap or dust cap is typically fitted over the bolt head depending on your headset or stem design. It is compatible with common stem clamping systems and headset preloads used across road frames. If your steerer is alloy, a star nut can still be used, but the Compressor offers a safer, non-invasive alternative for any carbon or carbon-laminated steerers.

Who It's For

This expander is aimed at road cyclists, mechanics and frame builders who run 1 1/8" carbon steerers and want a lightweight, non-destructive solution to preload their headsets. It's ideal for riders who prioritize frame longevity and clean serviceability—from everyday commuters to racers and weekend club riders. If you’re converting a frame to carbon-compatible hardware or simply replacing a damaged star nut, the FSA Compressor gives reliable performance without the risk of splitting or crushing the steerer tube.

Key Features

  • ✓ Carbon-safe expander for 1 1/8" / 28.6mm steerers, avoids star nut damage
  • ✓ Lightweight anodized aluminium body keeps added mass to 33g
  • ✓ Stainless steel threaded bolt for corrosion resistance and strength
  • ✓ Removable, serviceable design—extract without damaging the steerer
  • ✓ Sleek black finish matches most headset and stem aesthetics
  • ✓ Simple installation: wedge expands inside steerer to hold preload
  • ✓ Replaces star nut where steerer material is carbon or composite

Specifications

Primary Color Black

Product Identifiers

Vendor Item # 160-3010
UPC 400310000651

Frequently Asked Questions

Will this expander work on alloy steerers?

Yes — the expander will hold inside alloy steerers, but many mechanics still prefer a traditional star nut for aluminium since it bites cleanly and is sometimes lighter to install. The Compressor is primarily chosen to protect carbon or composite steerers.

Does the package include a top cap or dust cap?

This product is the expander/bolt assembly only. You will typically fit a separate top cap or headset dust cap over the bolt head—most aftermarket top caps are compatible with the M6-style bolt head used by this expander.

How tight should I torque the bolt when preloading the headset?

Preload the headset by snugging the bolt until bearing play is removed, then tighten the stem clamp bolts to manufacturer torque. As a guideline, keep top-cap preload low—around 2–3 Nm—then lock the stem at its specified torque. Avoid over-tightening the expander bolt.

Can this expander be reused if removed?

Yes. The Compressor is designed to be serviceable and removable. If removed carefully, it can be reinstalled, though inspect the wedge and bolt for wear or damage before reuse.

How does an expander compare with a star nut?

Expanders anchor via an internal wedge, so they don't puncture or deform the steerer wall like star nuts do. That makes them the recommended choice for carbon steerers and for easier serviceability, while star nuts remain a simple solution for many alloy steerers.

Buying Guide

When choosing an expander or top-cap system for a carbon steerer, match the diameter (1 1/8" / 28.6mm) and prioritize designs that avoid internal crushing. Look for lightweight, corrosion-resistant materials like anodized aluminium and stainless hardware. Consider whether you want a removable, reusable expander versus a one-time star nut—expanders are the safer, more serviceable choice for carbon. Also factor in aesthetics and compatibilities: a black anodized expander blends with most cockpits, but make sure you have a compatible top cap or dust cap and the correct stem clamp torque specs from your stem manufacturer. Keep handy carbon assembly paste and a torque wrench for safe, repeatable installation.

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