FSA Micro ACB
Micro ACB
FSA

FSA Micro ACB

In Stock

Sealed FSA Micro ACB cartridge bearing for 1-1/8" integrated headsets. Durable steel construction with black seal — sold per unit for straightforward replacement.

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Available Options

Option Price Availability
FSA, Bearing for 28.6mm Integrated Headset, 45°x45°, 1-1/8'' (28.6mm), Steel — In Stock
FSA, Micro ACB Black Seal Bearing, 36°x45°, 1-1/8'' (28.6mm), Steel — In Stock

Product Details

Overview & Technology

FSA Micro ACB is a sealed cartridge headset bearing engineered for 1-1/8" (28.6mm) integrated headsets. Available in 45°x45° and 36°x45° contact-angle variants, the Micro ACB uses hardened steel races and precision rollers for consistent steering performance and long service life. The black rubber seal keeps grease in and contaminants out, reducing maintenance and keeping friction low. Each unit is pre-assembled and pre-lubricated, which means fast, clean replacement with predictable bearing preload and smooth rotation right out of the box. The sealed cartridge design simplifies installation and removal compared with loose bearing systems and offers reliable performance in wet and muddy conditions.

Key Features

Built for durability and everyday reliability, the Micro ACB brings FSA's headset know-how to a compact sealed cartridge format. Key construction details deliver measurable benefits on the road and in mixed-surface riding. • Hardened steel races for wear resistance and predictable longevity. • Black rubber seal to keep out water, grit and road grime. • Pre-greased cartridge reduces initial break-in and simplifies maintenance. • Available contact angles (45°x45°, 36°x45°) to match factory cups and headset designs. • Sold per unit — replace single bearings as needed for economical servicing.

Fit & Compatibility

The Micro ACB is specified for integrated headsets with a 28.6mm inner diameter (1-1/8" steerer). Confirm your headset cup angle before ordering: the product is offered in both 45°x45° and 36°x45° contact geometries to match common headtube/headset standards. Part number 160-1647 / 150136 corresponds to the 45°x45° variant (bearing number 870E-RS). Because these are sealed cartridge bearings, they drop into compatible headset cups designed for press-fit cartridges. Use a headset press or appropriate drift to avoid damaging the seal or race; do not hammer the bearing directly. If you run an unusual tapered or zero-stack system, verify inner/outer diameters before purchase.

Who It's For

This bearing is ideal for riders and mechanics who want a low-maintenance, reliable replacement for integrated 1-1/8" headsets. Road riders, commuters, and cyclocross racers with older or classic headsets that use 28.6mm integrated cups will appreciate the simple swap-in fit and sealed protection. It's also a practical spare for workshop techs and home mechanics who keep common headset parts on-hand — especially useful when servicing bikes exposed to wet, salty, or gritty conditions where a sealed cartridge noticeably extends service intervals.

Key Features

  • ✓ Sealed cartridge bearing with black rubber seal for contamination protection
  • ✓ Hardened steel races for durability and long wear life
  • ✓ Pre-greased, pre-assembled unit for quick replacement
  • ✓ Available in 45°x45° and 36°x45° contact-angle variants
  • ✓ Specifically for 1-1/8" (28.6mm) integrated headset cups
  • ✓ Sold per unit — replace only the worn bearing as needed
  • ✓ Manufacturer part #: 160-1647, bearing number 870E-RS

Specifications

Number 870E-RS
Bearing Dimensions 45°x45°, 1-1/8''
Material Steel

Product Identifiers

Vendor Item # 160-1647
UPC 400310040268

Frequently Asked Questions

What does 'sold per unit' mean?

Sold per unit means each listing is for a single cartridge bearing. Most headsets use two bearings (upper and lower), so order two if you plan to replace both sides at once.

How do I know whether to choose 45°x45° or 36°x45°?

Check the contact angle stamped on your existing bearings or the headset documentation. The angle must match the headset cup seating surfaces. If unsure, remove the old bearing and inspect the edge or consult the bike or headset manufacturer.

Can I use this bearing in tapered or zero-stack headsets?

No. This cartridge is designed for integrated headsets with a 28.6mm ID (1-1/8"). Tapered or zero-stack systems often require different dimensions and cup designs — always confirm inner and outer diameters before buying.

What tools do I need to install the Micro ACB?

Use a headset press or a drift sized for cartridge bearings to press the unit squarely into the cup. Avoid hammering the bearing directly to prevent seal or race damage. Light grease on the outer cup can ease installation.

How long will a sealed cartridge bearing last?

Service life depends on riding conditions and maintenance. In dry conditions a sealed steel cartridge can last several years; in wet or gritty environments expect shorter life. The black seal helps extend life by keeping contaminants out.

Is there a ceramic option for this bearing?

This Micro ACB is a steel-race, steel-roller sealed cartridge. FSA and third-party manufacturers may offer ceramic or hybrid bearings for some headsets; check compatibility and benefits before switching.

Buying Guide

When buying headset bearings, first identify your headset type (integrated, semi-integrated, or external cup) and measure the inner diameter of the cup and the contact angle. For integrated 1-1/8" systems, the Micro ACB is a common sealed option — pick the contact-angle variant that matches your cups (45x45 or 36x45). Decide between steel and premium ceramic options based on budget and performance goals; sealed steel cartridges like the Micro ACB offer the best balance of durability, cost, and low maintenance for most riders. Finally, remember these are sold per unit — order two for a full headset refresh and keep a spare for quick roadside or workshop swaps.

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