27.2 mm seatpost (27.2 mm) vs 30.9 mm seatpost (30.9 mm): specs compared
Updated 05 September 2026.
3
specs differ
27.2 mm seatpost (27.2 mm) and 30.9 mm seatpost (30.9 mm) differ on 3 specs: diameter, designation, typical frames.
| Spec | 27.2 mm seatpost (27.2 mm) | 30.9 mm seatpost (30.9 mm) |
|---|---|---|
| Diameter | 27.2 mm | 30.9 mm |
| Designation | 27.2 mm | 30.9 mm |
| Typical frames | the de facto standard on modern road and gravel frames, and many hardtail and lightweight full-suspension frames | many mountain bikes and full-suspension frames, and one of the two common dropper-post diameters |
Questions and answers
How do 27.2 mm seatpost (27.2 mm) and 30.9 mm seatpost (30.9 mm) compare?
27.2 mm seatpost (27.2 mm) and 30.9 mm seatpost (30.9 mm) differ on 3 specs: diameter, designation, typical frames.