Seatpost
frame
The seatpost is the tube that connects the saddle to the frame. It slides into the frame's seat tube and is held by a clamp.
Key seatpost specs:
- Diameter — must match the seat tube (commonly 27.2mm, 30.9mm, 31.6mm; many modern frames use proprietary sizes).
- Length — must be enough to achieve correct saddle height.
- Setback — horizontal offset of the saddle clamp from the seatpost centreline.
- Material — alloy (durable, cheaper) or carbon (lighter, more vibration-damping in some cases).
Some modern aero bikes use proprietary aero seatposts that are not interchangeable with round seatposts.
For frames using carbon seatposts in alloy seat tubes (or vice versa), use the manufacturer-specified torque and friction paste / carbon assembly compound to prevent slipping or galling.
