30.9 mm seatpost (30.9 mm) vs 34.9 mm seatpost (34.9 mm): specs compared
Updated 05 September 2026.
3
specs differ
30.9 mm seatpost (30.9 mm) and 34.9 mm seatpost (34.9 mm) differ on 3 specs: diameter, designation, typical frames.
| Spec | 30.9 mm seatpost (30.9 mm) | 34.9 mm seatpost (34.9 mm) |
|---|---|---|
| Diameter | 30.9 mm | 34.9 mm |
| Designation | 30.9 mm | 34.9 mm |
| Typical frames | many mountain bikes and full-suspension frames, and one of the two common dropper-post diameters | modern trail and enduro mountain frames wanting the largest, stiffest dropper interface |
Questions and answers
How do 30.9 mm seatpost (30.9 mm) and 34.9 mm seatpost (34.9 mm) compare?
30.9 mm seatpost (30.9 mm) and 34.9 mm seatpost (34.9 mm) differ on 3 specs: diameter, designation, typical frames.