Bird Down Dropper V2.1 Dropper Post
What the checker says3will not fit256worth knowing
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 5824 verified mountain bike parts in this catalog. 5719 produced no finding of any kind; that is Down Dropper V2.1. Down Dropper V2.1 clears 5566. Each variant produces 3 distinct errors and 0 distinct warnings.
Will not fit
- Will not fiterror · FrameDropper too big: Frame seat tube is 30.9mm but Dropper is 31.6mm - a bigger post cannot fit a smaller tube. On 58 of the 258 verified frames in this catalog. Applies to all 3 variants.
- Will not fiterror · FrameDropper too small: Frame seat tube is 34.9mm but Dropper is 31.6mm. A shim or adapter may make other sizes or standards work, but that is a modification, not a fit. On 41 of the 258 verified frames in this catalog. Applies to all 3 variants.
- Will not fiterror · FrameDropper too big: Frame seat tube is 27.2mm but Dropper is 31.6mm - a bigger post cannot fit a smaller tube. On 6 of the 258 verified frames in this catalog. Applies to all 3 variants.
Worth knowing
- Worth knowinginfo · FrameLong-drop post: the Bird Down Dropper V2.1 (200mm) needs deep seat-tube insertion - check the maker's insertion calculator for your Antidote Carbonjack frame size. On 2 of the 258 verified frames in this catalog. Applies to 1 of 3 variants.
- Worth knowinginfo · FrameLong-drop post: the Bird Down Dropper V2.1 (200mm) needs deep seat-tube insertion - check the maker's insertion calculator for your Transition Spur Carbon frame size. On 2 of the 258 verified frames in this catalog. Applies to 1 of 3 variants.
Dropper insertion, Frame. 254 more findings from the same check, on up to 1 of the 258 verified frames each.
Open a variant in the builder to see the ones that apply to your own parts.
$133.80 to $180.62 MSRP
What the maker states
- Diameter
- 31.6 mm diameter
- Drop
- 125 mm of drop (on 1 of 3 variants); 170 mm of drop (on 1 of 3 variants); 200 mm of drop (on 1 of 3 variants)
A value shown as a set or a range differs between this model’s variants and is never one variant’s spec.
3 verified variants
| Variant | Drop | Price (MSRP) | Weight | Source | Last checked | Build |
|---|---|---|---|---|---|---|
| Down Dropper V2.1 | 200 mm of drop | $180.62 | not stated | maker’s page | 2026-09-20 | Build with this |
| Down Dropper V2.1 | 125 mm of drop | $133.80 | not stated | maker’s page | 2026-09-20 | Build with this |
| Down Dropper V2.1 | 170 mm of drop | $167.24 | not stated | maker’s page | 2026-09-20 | Build with this |
The rest of what the maker states1 not published
1 further field the checker looks for is not published by Bird, so we leave it blank rather than estimate it, and that check stays silent on this dropper post. It is cable pull. Each is recorded as “not stated by the maker (not checked)”.
Source: each variant links the maker’s own page in the table above. Last checked 2026-09-20.
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.
- 5DEV R-SPEC Trail/Enduro Cranks (Crankset) No conflicts found
- 9point8 Stout (31.8, 30mm) (Stem) No conflicts found
- ACID SLX 30 front (Front Wheel) No conflicts found
- ACID SLX 30 rear (Rear Wheel) No conflicts found
- Acros ZS44/ZS56 (Headset) No conflicts found
- Acros ZS56/ZS56 (Headset) No conflicts found
6 of 1858 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.