A seatpost is the tube that joins the bike’s frameset to the saddle, essential for a comfortable riding and a good performance.
The part of it that extends over the frame is what allows you to settle the height of your saddle, a very important aspect to consider before starting to pedal.
A correctly regulated seatpost will ensure comfort, a good posture and also good riding.
Amongst all seatpost in the market, several different typologies can be found. Choosing one or another will mainly depend on the cycling modality you practice.
Standard seatposts. They are the most widespread, used in many different disciplines. They are generally cylindrical in shape, with a diameter ranging from 21.15 to 31.8 mm.
Aero seatposts. These seatposts are flatter than conventional ones, and are very common on track and road bikes that have an aero geometry. An aero seatpost will improve the bike’s performance, speed and lightness.
Seatposts are tubes generally made with aluminium or steel. These materials are mainly chose because of their toughness, flexibility and light weight. Seatposts made with carbon can be found as well.
Aluminium: Bicycle seatposts made of aluminium are tough and rigid, capable of withstanding riding over very irregular terrain.
Steel: Seatposts made of steel are very resistant as well. They are safer and more comfortable in difficult conditions, as they can resist impact and vibration with more ease.
Carbon: Carbon seatposts are extremely light and offer a higher cushioning against vibrations caused by the terrain. They are not recommended for violent modalities such as MTB or cyclocross, as they are fragile and have almost no resistance to torsion.
Most bikes are generally designed to have a 27.2mm or 31.6mm seatpost. Its diameter will depend on the bike frame model, and you shall check your bike’s specs to see what seatpost size will be compatible with it.
Apart from its diameter, another important feature is the seatpost’s length. Each one of them has a mark showing the shortest length that can be fit inside the frame.
In case your seatpost is too long, you will be able to cut it to the desired length. However, if it is too short for your needs, there is no way to make it longer.