Our Guide to: Seatposts

What is a Bicycle Seatpost?

In a nutshell

A bicycle seatpost is essentially a tube that connects the bike frame to the bike saddle. Seatposts can also be called a seatpin, saddlepole, saddle pin or saddle pillar. A bike seatpost extends from the bicycle frame and this can be adjusted to suit the needs of the individual. Having the right seatpost is important to ensure you make the most of your ride and can also prevent you from straining your lower back in the long term. This buying guide determines the different types of seatposts for road and mountain bikes and what you can do with them.

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Dropper Posts

What is a dropper post?

A dropper post will allow you to quickly and easily lower your saddle for improved control when you hit technical terrain. In recent years, dropper seatposts have become a must-have item for mountain bikers. With so many models about, choosing the best dropper seat post can seem like a tricky task, but if you’re thinking of getting one, this guide will help you.

What dropper post model should I choose?

The most important task is to get a model that fits your frame. Seatpost diameters can vary, but most modern bikes use a diameter of 30.9mm or 31.6mm and there's a great choice of posts to fit these frames.

How are bike dropper posts operated?

Dropper posts are operated via a lever, which can sometimes be mounted on the post itself, but it's preferable to have a handlebar-mounted remote. These tend to cost more money but also mean that you can adjust the post as you ride, without needing to remove your hands from the bar.

That means that it's much easier and safer to put the post down at speed as you don't need to move your hands. Some posts, such as the RockShox Reverb use a hydraulic remote for minimal maintenance but most use cables, which need to be adjusted occasionally because they stretch. The Reverb also uses a remote lever which neatly integrates with Avid brakes by replacing the clamp, meaning a much less cluttered bar area. You need to select the correct model to suit which side of the bars you want to locate the lever.

What is the travel variation on dropper posts?

Dropper posts vary in overall travel, but most allow you to drop the saddle by around 125mm. The Rock Shox Reverb is available in two travel options, to allow those that need less drop, such as if they have a larger frame, to get the correct fit. Travel is either stepless, as with the Reverb, or fixed.

How many settings does the Fox DOSS have?

The Fox DOSS has three settings, one fully up for pedalling, 40mm down for more technical but still pedally terrain, or a fully down setting. It's very much personal preference, but many enduro racers prefer fixed position posts as they don't require you to 'hover' over the saddle. Many users favour specific posts, and if you’re unsure of which one to choose, it’s worth looking at some dropper seatpost reviews from a trusted website or cycling magazine.

Road Bike Seatposts

Why should I buy a new seatpost for my road bike?

Upgrading the seatpost on your road bike is a great way to lose weight and potentially add some comfort too, especially if you splash out on a carbon model. Compared to mountain bike seatposts, a road bike seatpost might look simple, but there’s a lot to consider when purchasing a new one. The best road bike seatpost for you will depend on what you want – low overall bike weight, comfort, or just everyday reliability.

What is the most comfortable type of seatpost?

First off, if weight and comfort come above cost, you’ll probably be looking at a carbon post. The carbon shaft is lightweight, and many will have a natural flex built in which helps dampen road buzz, making it ideal for longer days in the saddle – the Specialized S-Works SL Pave is a prime example.

What is the most cost-efficient type of seatpost?

If you don’t want to spend too much cash on a seat post, there are plenty of great aluminium options out there as well – like the Zipp Service Course SL. Aluminium road bike seatposts may not have the same level of vibration damping properties as carbon posts, but they are still relatively low weight. The cradle, which supports the saddle, might be carbon on pricier models, but if you want to save a bit of cash, aluminium cradles, have a minimal effect on performance.

Changing a Seatpost for Comfort vs Altering the Bike Fit

The other thing to think about is shape. Seatposts are either straight or offer ‘layback’ – this is where the clamp sits behind the shaft of the seatpost. In some seatposts, this layback gives some extra flex and therefore comfort, and in others, the layback can be used to effectively lengthen the feel of the bike. Generally speaking, unless you know you want a change, it’s worth keeping the same style that you currently have, as small changes to fit can have larger consequences in comfort. Many brands have their own system for clamping the saddle, but fortunately they’re all pretty universally compatible, that is, unless you have a saddle with particularly deep saddle rails – in this case you may find some seatposts struggle to accommodate them.

Do I need Di2 Compatible Seatposts?

The other thing to consider is whether you have a Di2 battery or not. FSA, for example, offer a number of seatposts, like the FSA SLK 20mm Di2 compatible carbon post, which are ready to accept a seatpost-style Shimano Di2 battery.