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FSA Orbit C-40-ACB Headset

What the checker says368will not fit

Run variant by variant through the mountain bike builder’s own engine. Every sentence below is the checker’s, unedited. Nothing here says this part fits your bike; it says what it does and does not fit among the parts we hold.

Checked against 6104 verified mountain bike parts in this catalog. 5876 produced no finding of any kind.

Will not fit

  • Will not fiterror · FrameHeadset lower cup mismatch: FSA Orbit C-40-ACB lower is IS52/40 but Antidote Carbonjack's lower head tube is ZS56 (S.H.I.S.) - cups press in at their exact bore only. On 2 of the 258 verified frames in this catalog.
  • Will not fiterror · FrameHeadset upper cup mismatch: FSA Orbit C-40-ACB upper is IS42/28.6 but Antidote Carbonjack's upper head tube is ZS44 (S.H.I.S.) - cups press in at their exact bore only. On 2 of the 258 verified frames in this catalog.

Headset upper, Frame. 165 more findings from the same check, on up to 1 of the 258 verified frames each.

Headset lower, Frame. 140 more findings from the same check, on up to 1 of the 258 verified frames each.

Headset steerer, Fork. 61 more findings from the same check, on up to 1 of the 490 verified forks each.

Open a variant in the builder to see the ones that apply to your own parts.

The checker compares the dimensions listed in what we check, and what we don’t. “No conflicts found” means no conflict among those dimensions — not a guarantee that a build works. Errors mean it won’t fit; warnings mean it works but check; infos are notes.

$61.00 MSRP·81.2 g

What the maker states

Upper
Assembly IS42/28.6 (S.H.I.S.)
Lower
Assembly IS52/40 (S.H.I.S.)
Steerer
Tapered (1.5-1.125)
Source

Source: the maker’s page. Last checked 2026-09-11.

Checked against

The checker ran this model against every verified part below that it has a slot for, the same way it checks a build in the builder. What follows is the verdict it actually produced for that specific pairing — not a recommendation, and not a guarantee any of these parts fits your own bike.

6 of 1881 counterparts with a page of their own that the checker actually probed this model against, in alphabetical order by brand and model — never by price, popularity or the verdict itself.

Where this sits

All FSA headsetsOpen a variant in the builder to see the ones that apply to your own parts