Bianchi Arcadex headset parts: ICR Bearings and Spacer Limits

Bianchi Arcadex headset parts need more identification than the description 1.5-inch bearings suggests. The carbon supplement dated 18 November 2024 includes an ICR exploded diagram with two different bearing entries, associated seals and split spacers. It also defines the permitted spacer height below the stem, making parts identification and cockpit-height planning closely connected questions.

Identify Bianchi Arcadex headset parts by their full entries

Page 7 names bearing H as 42 × 52 × 7 R2-45-45-2RS, identified as AC4252. Bearing J is 40 × 52 × 7 R2-45-45-2R, identified as AC4052. Despite their shared outside diameter and height, these are different table entries. Ordering two identical bearings from the broad 1.5-inch description would discard that distinction.

The diagram locates the entries within an assembly that also contains a compression ring, upper sealing, blue seal and base plate. Ask the workshop to match the relevant entry and adjacent parts to the actual assembly. A bearing dimension is valuable evidence, but it is not a substitute for checking which component in the exploded drawing needs replacement.

Treat the spacer range as a boundary

Page 8 states that spacer height below the stem must be between 5 and 35 mm. Both ends matter: the document gives a minimum as well as a maximum. It warns that exceeding 35 mm can compromise the fork steerer. The stated range is therefore a constraint on the documented assembly, not a casual suggestion for achieving a preferred riding position.

The parts list distinguishes a 5 mm half spacer, code 11.52.023, from a 10 mm half spacer, code 11.52.022. Those entries explain the component descriptions, but do not turn this article into an assembly recipe. Ask the specialist to assess the complete proposed height change, rather than adding parts simply because their nominal heights total an allowed number.

Account for routing when requesting service

The supplement shows hoses and casing passing through the ICR arrangement. It expressly reserves hydraulic tubing work to a specialist with the necessary expertise and tools. A headset request should therefore identify the installed cockpit and routing as well as the bearing or spacer, because the service concerns more than a loose stack of standard rings.

Take the dated diagram to the workshop and identify the exact carbon frame before ordering. The older Arcadex photograph supplied here does not show or verify this later ICR assembly. Keeping the diagram, frame identity and proposed change together avoids a parts request based only on appearance or the model-family name.

FAQ

Are the two listed bearings identical?

No. The table distinguishes the AC4252 42 × 52 × 7 entry from the AC4052 40 × 52 × 7 entry, with their respective full suffixes.

What is the documented spacer height below the stem?

The supplement gives a minimum of 5 mm and a maximum of 35 mm. Those limits concern the documented fork-and-cockpit arrangement.

Does an allowed spacer total make a height change a simple owner task?

No. The routed assembly still needs assessment, and Bianchi specifically reserves hydraulic tubing work to a qualified specialist dealer.

For the horizontal and width choices rather than bearing replacement, consult the AeroFlare size comparison. Find the full series on the Bianchi topic.

Sources: Bianchi carbon Arcadex supplement, 18 November 2024.