Find the best prices on seatposts for your bike from Easton, Thomson, Alien and more! If you think about where big forces must be supported as you bicycle, the handlebar and stem combo comes to mind, pedal axles must obviously be very robust, and though you might not think it at first, your bike seatpost has a big job to perform. Not only must it support your weight along the forces of direction going into your bike's seat tube, but it must also be laterally stiff to endure the side to side forces put on it as you lean into your bike while pedaling and cornering. This is why traditionally, bike seatposts were simply round tubes, since that design allows for forces to be dissipated in 360°. Of course, now carbon seatposts are designed in aerodynamic shapes, in which case the carbon layup must be done precisely to support your body weight in the vertical plane as well as have significant strength in the horizontal plane for left to right forces. One of the trickiest parts of seatpost design is the seatpost head, which must be a precise bolt pattern and configuration that securely latches onto your bike saddle rails. You might think that there is one seatpost head design that has become standard, but that's not the case – bike part manufacturers have come up with so many innovative designs, and you have your choice of what will work best for your bike set up. When shopping for a bicycle seat post, there are three main things to concern yourself with. The first is the seatpost length, which must be long enough to insert to a sufficient length into your bike seat tube, but also tall enough to give you the proper saddle height. The second thing is the seatpost diameter, in the case that you are buying a round seatpost. Common sizes are 25.8 mm and 28.6 mm, so check your bicycle carefully to know the exact size. The third thing that may come into play is whether your desired seatpost is straight or has a setback. A setback simply means that an angle is built in to the seatpost so that you can effectively move your saddle forward or backwards from what would be the straight seatpost position. A forward angled seatpost (let's call it a reverse setback!) is sometimes used by triathletes to create an effective steeper angle seat tube design, which is desirable for time trial style riding. Beyond those three considerations are the obvious ones of seatpost material, which is typically aluminum or carbon, and then pricing. There are also steel and titanium seatposts, though less readily available now than in the 1980s. Titanium seatposts were a hot trend, and they perform just fine, but you must use special anti-seize compound when installing a titanium seatpost in your bicycle lest it metallically fuse with your bike frame over time. Stick with aluminum or carbon. There is more to consider in seatpost designs, such as shock absorbing seatposts and height adjustment on-the-fly seat posts, which are useful for downhill mountain biking. We've got hundreds of seatposts here to choose from, with designs intended for road bikes, mountain bikes, and triathlon bikes.