Rigid seatposts provide the critical connection between your bike’s frame and saddle. And while you might think they are all the same, there are a number of key factors to consider, including diameter, length, offset, clamp type, and construction material.
Most rigid seatposts are made of either aluminum or carbon fiber. Choose aluminum if you’re not overly weight conscious and are looking to save a few bucks. Or opt for carbon fiber to shave grams and benefit from the material’s subtle bump-adsorbing capabilities. Just know that you will probably pay a little more.
Diameter is also an important consideration, as the post needs to properly fit inside your bike frame’s seat tube. The most common rigid seatpost diameters are 27.2mm, 30.9mm, and 31.6mm. Seatposts that are narrower can help smooth your ride due to a minimal amount of flex. Wider rigid seatposts are typically stiffer and do a better job of eliminating unwanted energy loss. And if you end up with a seatpost that’s too small for your bike you can use a shim, but of course you can’t make a wide seatpost fit in a narrow seat tube.
Next you’ll want to examine offset, which is the rearward distance a rigid seatpost’s clamp resides relative to the post’s main shaft. Zero offset posts are ideal for riders who prefer to sit more forward on the bike. Or choose some amount of offset to attain a more centered position on your bike.
Rigid seatpost length is governed by your frame’s geometry and size, and your personal saddle height. The majority of rigid seatposts come in just one length, but can be trimmed to shave weight. Just remember that all rigid seatposts have a minimum insertion distance that must be obeyed, lest you risk cracking your frame’s seat tube because of excessive leverage forces.
Clamp type is a reference to how your rigid seatpost clamps to the rails of your saddle. Most use either a one- or two-bolt system that also permits adjustment of saddle tilt and fore-aft position. The standard saddle rail size is 7mm, but there are some models with larger diameter rails, so make sure your seatpost and saddle are compatible. There are also a limited number of proprietary clamp designs such as single rail, so again make sure to confirm compatibility.
JensonUSA carries a huge selection of rigid seatposts from companies like ENVE, Thomson, Ritchey, Syncros, 3T, Zipp, Deda, FSA, Race Face, and Easton. If you have any questions, give one of our Gear Advisors a call at 888-880-3811. They will make sure you get the right seatpost for you and your bike.