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Dropper Seatposts: A Complete Buyer’s Guide

May 31, 2018
Dropper Seatposts: A Complete Buyer’s Guide

Widely lauded as the most important technological advancement to hit mountain biking circles since suspension technology, dropper seatposts are quickly becoming one of the most sought after features on a mountain bike.

Regardless of whether you’re looking to enter the world of dropper posts, or simply looking to upgrade, with the comprehensive information on all things dropper posts below, you’ll be dropping it like its hot in not time.

What is a Dropper Post?


Put simply, a dropper seatpost is a height adjustable seatpost that allows a rider to quickly and easily lower the seat height when riding along. A dropper seatpost operates via the use of a handlebar, or seatpost located remote lever.

There are a number of benefits to using a dropper seatpost, chief among is the ability to lower the seatpost down, and out of the way to allow you to lower your centre of gravity to dip, carve, pop and shred to your heart's content when attacking technical sections of trail.

How a Dropper Post Works


Dropper seatposts work in a remarkably similar fashion to an office chair, in that you put your weight on the dropper post and push the lever, the seat goes down. Lift your weight off the post and push the lever, and the seat returns to its original position. Of course, the technical inner workings are more complicated than that, but that’s the general gist of it.

The innards of dropper posts are typically pneumatic, meaning that pressurised gas or air is responsible for holding the seatpost in either its fixed or infinitely variable position.

Traditionally the first dropper posts were adjusted with a lever at the post itself. Whilst this is still used sparingly, these days a dropper post is almost exclusively operated via a remote lever mounted to the handlebars and connected either atop the shaft of the post or at its base via a mechanical cable or hydraulic hose.

Why Dropper Posts are of Benefit


Dropper posts have opened up the possibilities of just how quickly riders and their mountain bike can adapt to varying terrain. With the flick of a switch, riders now have the option of comfortable and efficient pedalling, or confident descending with ample room for the bike to move beneath them without a saddle in the way.

They are also allowing frame manufacturers to create bikes with steeper seattube angles, perfect to help with getting your weight forward for easier climbing, but then the ability to get the seat out of the way once the trail turns around.

Selecting a Dropper Post


As dropper posts continue to be developed, more and more key players are entering the market. Whilst this is good from both a technological and durability point of view, the sheer wealth of options on the market can be overwhelming for a new buyer. Below, we sift through the key aspects of dropper seatposts and what to consider in your search.

Seatpost Length and Travel


The amount of travel a dropper post has refers to the amount of up and down movement on offer. Most posts will come in a choice of lengths, often linked to the amount of travel, or drop, on offer.

Typically, droppers are available in travel lengths of 80mm,100mm, 125mm, and 150mm, however, both longer and shorter options also exist.

Before buying, make sure the post is long enough when extended to give your preferred pedalling height. Measure the amount of exposed seatpost you have in a fully extended pedalling position. Just like a standard post, droppers will have a minimum insertion line.

As the length of travel increases, the overall length of the post will grow. More commonly than a dropper being too short, is it being too long. Be sure that with the post fully extended, that the height will not be too much. If it is, look for a post with a shorter travel and shorter design.

Also, consider how much of the post will fit inside of your frame without clearance issues. Many droppers posts cannot be trimmed, so you’ll need to find a length that provides perfect pedalling height, but without excessive spare length.

For this reason, it’s important to take your riding style, frame size and height into account when selecting a dropper post. As an example, small frames will rarely be able to accommodate a 150mm travel dropper, while taller riders may need to seek out a post with extended travel.

Fixed or Infinite Adjustment

There are two ways in which a dropper posts extend through their travel, preselected (aka, fixed travel), and infinitely adjustable.

The vast majority of posts are going to offer infinite adjustment. That means you can stop the post at any point along its travel. This is largely the prefered option purely as it allows a rider the ability to fine tune their saddle height depending on the situation.

Alternatively, some dropper seatposts will come with preset, or fixed positions. Depending on the seatpost itself, the number of fixed positions can vary from a basic up and down, to as many as 10 preselected heights. The main advantage of a fixed dropper seatpost is that they provide consistent and repeatable heights for riders to get accustomed to. Another benefit, as claimed by a few brands, is that the fixed designs are simpler and therefore more reliable. However, our experience is that both types are comparable in the durability stakes.

Mechanical vs Hydraulic


Most dropper seatposts use hydraulic or pneumatic pressure to be raised up and down, but the question of mechanical and hydraulic refers to how the remote lever is attached to control the unit.

A full hydraulic dropper post uses a sealed hydraulic remote to control the seatpost. The system itself works much in the same way as a hydraulic brake cable, whereby a piston (the lever) pushes fluid through a hose which actuates the dropper at the other end. The advantages of hydraulic cabling is that it is impervious to debris, there’s no cable to wear out and the hose can be routed through any angle without increased friction. However, such a system may require fresh hydraulic fluid on a seasonal basis. Currently, RockShox is the only company to offer a full hydraulic seatpost.

By comparison, just about every other dropper post on the market uses a mechanical lever, connected to a gear cable for control. Mechanical levers use a braided stainless steel cable that is threaded through gear housing and attached to the dropper post. The main advantage of a mechanical lever is that they are simpler and easier setup than their hydraulic siblings.

Handlebar Remote vs Seatpost Lever


A dropper seatpost is actuated via the use of either a handlebar located remote or a seatpost lever. The remote, or lever itself will be connected to the dropper post either via a mechanical cable, or via a hydraulic hose.

As previously mentioned, seatpost levers were traditionally the more popular when the technology was in its infancy, however, as dropper seatposts are becoming more refined, handlebar remotes are by far the more popular option. This is largely due to the fact it’s much easier to adjust on the fly without having to remove your hands from the handlebars.

Different brands each have their own dropper post lever designs. Older designs typically place the lever on top of the handlebar on the left side, allowing space for a left-hand (front) gear shifter. The rise of 1x gearing has seen space become available for a more ergonomic below handlebar position for the dropper remote.

In this way, the latest remote designs work much like a shift lever, operated by your left thumb. Where some posts don’t come with such a remote, aftermarket options are becoming readily available, with the likes of WolfTooth, OneUp, PRO, RockShox (to work with RockShox posts only) and others offering such an upgrade for relatively little cost.

Internal (Stealth) vs External Cable Routing


As with brake and gear cabling, dropper seatpost cabling can be routed both internally and externally of the frame.

Internal cable routing, commonly referred to as stealth cable routing, is the most common method of cable routing on modern mountain bikes. Following the same cable guides as gear and brake cables, internal cable routing means that a dropper post is connected to the remote lever at the shaft of the post. There are a number of benefits to internal cable routing including a sleeker aesthetic, reduced risk of contamination from dirt and debris and reduced chance of damage in the event of a crash.

External cable routing is common on more affordable dropper posts and for those fitting a dropper post to an older or entry-level mountain bike frame. The cables are typically routed outside of the top tube or downtube and attach to either the head or shaft of the post itself. The advantages of an externally routed dropper post is that they’re easy to fit and service. No having to fish around inside the frame looking for cable ends, just attach the cables to your frame, insert the post as per normal and away you go.

If looking for an external routed post, we strongly suggest picking one that sees the cable attach to the shaft, instead of the head. This is simply because the fixed nature of the shaft-mount means your cable length does not need to adjust to the seatpost height, therefore providing a far cleaner aesthetic and less chance of damage.

Seatpost Diameter


As is the case with standard, or fixed seatposts, dropper seatposts are available in a number of different seatpost diameters. The most common options are 30.9mm, 31.6mm and 34.9mm, however, skinnier 27.2mm posts are also available in select models.

The overall diameter will be dictated by the frame you plan to fit the dropper seatpost into. The easiest way to check this is to remove your existing post and read the size markings at the bottom of it. If your post is a weird size, then you may need to consider going a size smaller in the dropper post and finding a suitable shim to make it fit.

Larger diameter seatposts are regarded as adding stiffness and strength, as well as providing greater space for reinforced internal parts, all leading to improved durability. For this reason, many of the latest mountain bikes have increased seattube diameters.

Saddle Clamps


Just like choosing a rigid seatpost, saddle clamp design is worth considering in a dropper too. Most posts use the twin-bolt method, which allows wide compatibility with both metal and carbon railed saddles, and near infinite angle adjustment. Given the choice, this is our preference.

However, a number of posts make use a single-bolt side clamp, which does require addItional parts to swap between metal and carbon railed saddles.

Budgets and Expected Expenses


Given the technical nature of these posts, it should come as little surprise to learn that even a budget dropper seatpost is likely going to cost more than a rigid carbon seatpost. No longer what you’d deem a niche product, dropper seatposts are now filtering down into more affordable price points as more companies enter the fray. As with any affordable bicycle component, Keith Bontrager’s famous quote is worth taking into account “Strong, light or cheap, pick two”.

$200 and Under

Dropper posts at this price are likely going to be much heavier than their pricier rivals, due to simpler internals and the materials used. They will likely be much more basic in function, and feature a non-stealth cable routing design. Posts to consider at this price point include the KS Suspension ETEN, Giant Contact dropper post and the Brand-X Ascend.

$200 – $350

Moving beyond $200 and dropper seatposts start to increase in technicality, featuring strengthened internals and internal cabling. These features combine to bring the weight of the post down, whilst increasing durability. Posts to look out for in this price range include the Bontrager Drop Line, Race Face Aeffect and the KS Suspension LEV Si.

$350 – $500

Offering arguably the most choice to consumers, the $350 to $500 price bracket is stacked with options that are sure to provide riders with everything they need from a dropper seatpost.

Droppers at this price point see internals nearing top specification, with improved seals for smoother actuation, lower lever force and increased durability. The weight of a dropper at this price point is also likely to be 200~ grams lighter than budget options due to the use of more lightweight materials. It’s this price point, and the one below, that offers the best value for money.

Options to consider at this price point include the Fox Transfer Performance, Crank Brothers Highline and the Specialized Command Post.

$500 Plus

Moving to the top end of the dropper post hierarchy and expect to find professional level options that are dripping with advanced pneumatic and suspension technology. Shafts are likely to feature special coatings to aid in smoother actuation, the internals are likely to be among the best on offer for longer service life intervals and weight drops even more with the help of single piece forged inner posts.

Options to consider at the top-end of the market include the USA-made Thomson Elite Covert dropper seatpost, RockShox Reverb Stealth (hydraulic) and the Fox Transfer Factory seatpost.

Cable Routing Tips


As mentioned earlier, some external routed posts place the cable at the head, others at the shaft. The former sees the cable move and shift in length as the post is adjusted, the latter allows the cable to be fixed in length. If using the former, be sure to leave ample cable length free to allow resistance-free extension.

Older frames aren’t likely to have provisions for dropper posts, and so zip ties or even shrink wrap (if replacing all cables) can be your friend for cable management. For bikes with external cable routing, running the dropper post cable along the rear brake hose with zip ties is a common technique for a clean look.

When installing a stealth seatpost (with internal cable routing), be sure to leave sufficient hose or cable length to allow the post to be removed from the bike without having to undo anything. It may not be obvious why, but it’ll make sense when it’s time to service your seatpost (more on that below), or fit your bike into a travel case.

Maintenance and Servicing

Riders ask a lot from their dropper seatposts. Similar to a suspension component, a dropper seatpost will have constant forces being applied to it, so it’s important to keep your post properly maintained so that it works as intended.

As dropper seatposts use pressurised gas and/or hydraulic fluid in order to function, they’ll likely need to be serviced by a professional once a year to ensure smooth actuation and ongoing durability. Ensuring that your post is cleaned after every ride and free from debris will go a long way to ensuring the ongoing serviceability of your post.

Two common issues we see are incorrect cable tension (or poor bleed), leading to a sluggish travel extension and the seatpost binder bolt being done up too tight, resulting in compressed dropper internals. Additionally, be careful to not lift the bike from the saddle when the dropper is in its lowest position, some droppers (but not all!) don’t like this and will suck air into the system.

Common signs of a dropper in need of a service include leaking seals, a dropper that sags in height under your weight, excessive play, sluggish extension or weird noises.

Much like the suspension on your mountain bike, dropper post servicing is best left to a professional in your local bike shop due to their highly technical nature. A service will typically consist of seals being replaced, hydraulic fluid being bled and replenished, or the gas/air being pressurised within.

For more experienced home wrenches working on their dropper-equipped steeds, be careful when clamping dropper posts in workstands. Most manufacturers suggest not clamping the sliding surface of the dropper in a workstand, however, we’ve found extending the post to full height, wrapping it in a clean and soft rag, and then clamping it carefully works just fine.

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