30.6 mm seatpost (30.6 mm)
Which frames use a 30.6 mm seatpost, and how it differs from the sizes either side of it.
Published dimensions
| Diameter | 30.6 mm |
|---|---|
| Designation | 30.6 mm |
| Typical frames | some older oversized aluminium road and MTB frames |
Used on: some older oversized aluminium road and MTB frames.
30.6 mm is an older oversized size that sits between the road 27.2 mm and the MTB 30.9 mm. It is uncommon today, so measure the bore carefully, because a 30.9 mm post will not enter a 30.6 mm tube.
Frames and related seatpost sizes
27.2 mm seatpost27.2 mm30.9 mm seatpost30.9 mm31.6 mm seatpost31.6 mm34.9 mm seatpost34.9 mm25.4 mm seatpost25.4 mmBSA bottom bracket shellthe frame's other threaded interface
SOURCES: Sheldon Brown, Seatpost Size Database · BikeGremlin, Seatpost diameter sizes (standards)