Seat clamp is used to secure the seatpost when inserted into the bicycle frame. It comes with different diameter as each bicycle seat tube varies in its diameter. It is important to note that the internal diameter of the seat clamp must be similar to the external diameter of the seat tube. Common sizes of seat clamp are 28.6mm, 31.8mm and 34.9mm.
There are two types of seat clamps:
- Quick Release Seat Clamp (Tightened using lever)
- Allen Key Seat Clamp (Tightened using allen key)
The tightness of the seat clamp is important for safety concern.
- Too loose will cause the seatpost to move and slide downwards
- Too tight will cause the seatpost clamp area on the frame to crack
Things to take note to ensure the proper usage of seat clamp:
- Minimum insertion depth of 8cm on seatpost is needed before the seat clamp can be tightened safely
- Seat clamp to be placed in line with the seat tube of bicycle frame
- Maximum torque is often written near the seat clamp area