Carbon-Ti X-Plug Over Sized headset expander.

Click anywhere or press Esc to close.

Carbon-TiX-Plug OS

$26.00
Built for
  • road
  • gravel
  • mtb

Does it fit my bike?

In stock Ships from Seattle, WA

  • Free USPS Ground Advantage on orders of $50 or more.
  • $5 flat rate USPS Ground Advantage on orders under $50.
  • Expedited shipping is available for $10 via USPS Priority Mail.

Overview

The Carbon-Ti X-Plug is a superlight headset expander, or compression plug, that sets your headset preload and gives the top-cap bolt something to thread into. It is CNC-machined from 7075-T6 aluminum and grips the inside of the steerer, so it works with carbon or aluminum steerers in place of a star nut. This is the oversize (OS) size, for a 1 1/4 inch steerer. It is also made in a standard size for a 1 1/8 inch steerer.

Why we love it

We love that this hidden part does two jobs well and saves weight while it is at it.

  • 01It expands inside the steerer to set your headset preload, the job a star nut does, but you can remove it and adjust it.
  • 02It gives the top-cap bolt a secure thread, so your Carbon-Ti stem cap has something to pull against.
  • 03It is machined from 7075-T6 aluminum and works with carbon or aluminum steerers, at just 14 to 17 grams.
Why it makes the cut. Hammer & Howl only carries parts we believe are among the best in the business. It is the quiet half of a tidy, lightweight setup at the top of your fork.

Specifications

What it is
A removable headset expander (compression plug)
Size
Oversize (OS), for a 1 1/4 inch steerer
Steerer fit
Carbon or aluminum steerers; inner diameter 24 to 28 mm
Material
7075-T6 aluminum, CNC machined
Replaces
A star nut, for setting headset preload
Best for
A threadless headset, paired with a lightweight top cap
Made in
Italy

What's included

  • One Carbon-Ti X-Plug OS headset expander in the oversize size

Not included: A top cap or bolt. The X-Plug sets your preload and holds the top-cap bolt, but the cap and bolt are separate. The Carbon-Ti X-Cap Carbon and the Carbon-Ti X-Cap Titanium are the matching Carbon-Ti top caps, and each comes with its own bolt.

Will it fit your bike?

Compatible with

  • Threadless headsets with a 1 1/8 inch steerer (the standard size), with a steerer inner diameter of 21.2 to 25 mm
  • Threadless headsets with a 1 1/4 inch steerer, using the oversize (OS) size, with a steerer inner diameter of 24 to 28 mm
  • Carbon or aluminum steerers

Not compatible with

  • Threaded headsets, which use a locknut, not a top cap and expander
  • Steerers whose inner diameter falls outside the size you choose (measure to be sure)
  • 1 1/8 inch and 1 1/4 inch steerers mixed up: match the size to your steerer

Confirm before ordering

Check your steerer size (1 1/8 inch or 1 1/4 inch) and, ideally, measure the inner diameter. If you are not sure, confirm with your bike mechanic or contact Hammer & Howl before ordering.

A headset expander fits by the inside diameter of your steerer. The standard X-Plug suits a 1 1/8 inch steerer with an inner diameter of 21.2 to 25 mm. The oversize (OS) X-Plug suits a 1 1/4 inch steerer with an inner diameter of 24 to 28 mm. It grips the inside of the steerer and holds the top-cap bolt, so it works in place of a star nut on carbon or aluminum steerers. Measure your steerer's inner diameter if you are not sure, since a carbon steerer's wall thickness varies.

Questions

What does a headset expander do?

It sets the preload on your headset bearings and gives the top-cap bolt a secure thread. It grips the inside of the steerer, so it does the job a star nut does, but it can be removed and adjusted. It is the standard choice for a carbon steerer, where a star nut is not used.

Which size do I need?

Match it to your steerer. The standard X-Plug fits a 1 1/8 inch steerer with an inner diameter of 21.2 to 25 mm. The oversize (OS) X-Plug fits a 1 1/4 inch steerer with an inner diameter of 24 to 28 mm. Most road, gravel, and mountain bikes use the standard 1 1/8 inch size.

Does it replace a star nut?

Yes. The X-Plug does the same job as a star nut, setting your headset preload, and it holds the top-cap bolt. Unlike a star nut, it can be removed and reused, which is why it suits carbon steerers, where a star nut is not used.

Will it work with my Carbon-Ti stem cap?

Yes. The X-Plug gives the top-cap bolt a secure thread to pull against, so it pairs directly with the Carbon-Ti X-Cap Carbon Matte Stem Cap, which is made in the 1 1/4 inch Over Sized size this expander fits. Choose the X-Plug size that matches your steerer.

Does it come with a top cap?

No. The X-Plug is the expander only. Add the Carbon-Ti X-Cap Carbon Matte Stem Cap in the 1 1/4 inch Over Sized size for the visible top cap, which comes with its own bolt.

This pairs well with

Carbon-Ti X-Cap Carbon Matte Stem CapStem cap