30.9 mm seatpost (30.9 mm) vs 31.6 mm seatpost (31.6 mm): specs compared
Updated 05 September 2026.
3
specs differ
30.9 mm seatpost (30.9 mm) and 31.6 mm seatpost (31.6 mm) differ on 3 specs: diameter, designation, typical frames.
| Spec | 30.9 mm seatpost (30.9 mm) | 31.6 mm seatpost (31.6 mm) |
|---|---|---|
| Diameter | 30.9 mm | 31.6 mm |
| Designation | 30.9 mm | 31.6 mm |
| Typical frames | many mountain bikes and full-suspension frames, and one of the two common dropper-post diameters | many mountain bikes and gravel frames, older oversized road frames, and the other common dropper-post diameter |
Questions and answers
How do 30.9 mm seatpost (30.9 mm) and 31.6 mm seatpost (31.6 mm) compare?
30.9 mm seatpost (30.9 mm) and 31.6 mm seatpost (31.6 mm) differ on 3 specs: diameter, designation, typical frames.