FSA Orbit 1.5Zs
FSA

FSA Orbit 1.5Zs

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The FSA Orbit 1.5ZS is a lightweight, complete ZeroStack headset (125 g) with ACB sealed bearings and forged/CNC aluminum cups — built for tapered 1-1/8" to 1.5" forks.

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Product Details

Overview & Technology

Precision engineering in a compact ZeroStack design. The Orbit 1.5ZS pairs a forged alloy upper cup with a CNC-machined 1.5" lower cup to deliver a rigid interface between frame and fork while keeping stack height low at 19.8 mm. ACB (angular contact bearing) geometry uses 36°/45° bearing angles for dependable preload and predictable steering under heavy loads. Sealed ACB bearings (blue seal upper, black seal lower) reduce contamination and maintenance while preserving smooth rotation over time. At just ~125 g, this headset saves grams without compromising the structural stiffness riders need on modern mountain rigs and trail bikes.

Key Features & Performance

Construction and materials: The upper cup is forged aluminum for impact resistance and precise fitment; the lower cup is CNC-machined to tight tolerances for concentric bearing seating and optimized load distribution. Both cups are anodized black for corrosion resistance and clean aesthetics. • ACB sealed bearings (36°/45°) for axial and radial load handling • ZeroStack (ZS44/28.6 upper | ZS56/40 lower) to suit modern frames • Low 19.8 mm stack height keeps the cockpit compact and stiff • 125 g recorded weight balances durability and lightness

Fit, Compatibility & Installation

Designed for tapered setups: Fits 1-1/8" to 1.5" tapered steerer tubes and ZS44/28.6 upper and ZS56/40 lower head tube interfaces. The headset is intended for frames with 50 mm / 62 mm OD head tube dimensions commonly found on contemporary mountain and trail bikes. Crown race diameter is 40 mm. Installation uses standard headset presses and tools for ZeroStack cups. The Orbit 1.5ZS ships as a complete headset (upper and lower cups plus ACB sealed bearings) — confirm whether your fork requires a separate crown race or uses the integrated seat specification before installation. Preload is achieved with an 8 mm top-cap style bolt (variant dependent).

Who It's For

The Orbit 1.5ZS is aimed at mountain riders and trail enthusiasts who want a durable, lightweight integrated headset that maintains precise steering on rough terrain. It's a strong choice for builders upgrading to sealed ACB bearings and tighter tolerances without a full race-to-weight tradeoff. Choose this headset if you run a tapered fork on a modern ZS head tube, value low stack height for cockpit setup, and prefer sealed bearings that cut down on maintenance while delivering crisp handling on long rides and demanding trails.

Key Features

  • ✓ ZeroStack ZS44/28.6 upper and ZS56/40 lower for modern frames
  • ✓ ACB sealed bearings (36°/45°) for sustained smooth steering
  • ✓ Forged aluminum upper cup for impact resistance and strength
  • ✓ CNC-machined 1.5" lower cup for concentric bearing seating
  • ✓ Low 19.8 mm stack height keeps cockpit compact and stiff
  • ✓ Lightweight complete headset — approx. 125 g for upgrades
  • ✓ Compatible with tapered 1-1/8" to 1.5" steerer tubes
  • ✓ Anodized black finish resists corrosion and looks clean

Specifications

Bearing Grade ACB Sealed
Crown Race Diameter 40mm
Lower Cup 56mm
Headset Type ZeroStack
Upper Cup 44mm
Headset Weight 125g
Misc 36°/45° ACB
Material Aluminum
Primary Color Black
S.H.I.S. ZS44/28.6 | ZS56/40
Steerer Tube 1-1/8''-1-1/2''
Stack Height 19.8
Headset Position Complete
SHIS Upper ZS44/28.6
SHIS Lower ZS56/40

Product Identifiers

Vendor Item # 141-2044
UPC 400310003317

Frequently Asked Questions

What steerer and head tube sizes does this headset fit?

The Orbit 1.5ZS fits tapered steerer tubes from 1-1/8" to 1.5" and is made for ZeroStack head tubes with SHIS ZS44/28.6 upper and ZS56/40 lower standards. It suits head tubes with the common 50 mm / 62 mm OD dimensions listed in the specs.

Are the bearings sealed and serviceable?

Yes — the headset uses ACB sealed bearings (blue seal upper, black seal lower) designed to keep dirt and water out. Sealed bearings reduce routine maintenance; when service is needed you can remove, clean, and regrease or replace the bearings using standard headset tools.

Does the headset include all parts needed for installation?

This is a complete ZeroStack headset including upper and lower cups and the ACB sealed bearings. Confirm whether your fork requires a separate crown race; the headset specifies a 40 mm crown race diameter for compatibility.

What tools do I need to install the Orbit 1.5ZS?

A standard headset press for ZS cups, a torque wrench for top-cap preload and stem bolts, and common bike tools are all you need. Pressing should be done evenly to avoid distorting the cups; if you’re not comfortable with a press installation, have a qualified shop fit the headset.

How does the 36°/45° ACB angle affect performance?

The mixed 36°/45° angular contact bearings provide a balance between axial preload capacity and radial load support. This geometry helps maintain tight steering under braking and cornering loads while preserving smooth rotation — ideal for mountain and trail riding demands.

Is this headset suitable for e-bikes or downhill use?

While the Orbit 1.5ZS is robust and sealed for trail use, for heavy-duty enduro, downhill, or high-mileage e-bike applications you may prefer headsets specifically rated for extreme loads. It remains an excellent fit for most mountain bikes and aggressive trail builds.

Buying Guide

When choosing a ZeroStack headset, match the SHIS codes on your frame and fork — ZS44/28.6 for the upper and ZS56/40 for the lower in this unit. Confirm steerer diameter (1-1/8"–1.5") and crown race size (40 mm) to ensure compatibility. Decide whether you prioritise lowest weight, maximum durability, or easiest servicing. The Orbit 1.5ZS is a balanced option: forged and CNC aluminum construction, sealed ACB bearings, and low stack height make it a straightforward upgrade for mountain and trail bikes that demand responsive handling and low maintenance.

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