A dropper seatpost is without doubt one of the best upgrades you can make to your mountain bike.So we take a look at what to consider and some of the best seat dropper posts on the market.
Put simply, they allow you to lower you saddle height while riding, giving you much more space to move around on the bike while descending.
When it's time to go back up, you let it pop back to the correct height for efficient pedalling, all without having to stop.
Of course, this makes them ideal for enduro-style racing, where being able to quickly switch from sprinting uphill at attacking down a descent is essential.
However, even trail and XC riders can reap the benefits of using a dropper post.
There are a huge number of different styles on the market, so we'll run though the main differences before showing you the best ones we've tested.
How much travel do I need?
How much travel the post has dictates just how far out of the the way you'll be able to get your saddle while still having the best position for pedalling.
Cheaper posts tend to have less travel — ensuring the internals of the post are strong enough to stand up to the extra leverage is no easy task.
While a drop of around 100mm is certainly enough to see the benefit of a post, we've found that you still have to make a compromise on whether you want the saddle to be totally out of the way when descending or having the post high enough for pedalling duties.
Most posts on sale today have around 125-150mm of travel, which is fine for most riders, though recently there has been a trend for longer travel posts of anywhere from 170mm up to a whopping 200mm.
While these are excellent for taller riders, if you have shorter legs you might find it's possible to have the post as low as it can go in your frame yet have the saddle too high when the post is at full extension.
It's important to make sure that this isn't the case before buying a longer travel post, so measure your existing seatpost from the saddle rail to where it enters the frame, then compare this to the length of the dropper post from saddle rail to below the collar.
If it's the same or less, you'll be fine, but if it's greater then it won't work.
What's the best kind of adjustment?
Fixed or stepless travel?
There are two main kinds of post on the market, those that have fixed settings that the post stops at through the travel and those that do not, with the latter often referred to as stepless or infinitely adjustable.
There are benefits and drawbacks to both. Posts with fixed travel settings allow you to very quickly move the post into the required position without having to stay sat on the post until it reaches the correct height.
Stepless posts give you much more freedom to have your saddle wherever you want and which you prefer is very often a personal thing, but the majority of posts on the market at the moment are stepless designs.
All posts require some sort of spring to return the saddle to the fully upright position and a locking mechanism to hold it in place.
Early designs simply used coil springs and pins to do the job, but these were unrefined and often returned the saddle back towards your bottom at an unnerving speed.
It's common to still see mechanically locking designs in conjunction with an air spring, but most designs now use a fully sealed hydraulic cartridge that contains both a pressurised charge and the mechanism that allows the adjustment.
There are a number of advantages to this, namely that the body of the post, which needs to cope with very heavy loads, doesn't also have to be airtight and so lower friction seals can be used for a lighter action.
If something does go wrong with the post, then it's also much quicker and easier to drop in a replacement cartridge rather than repairing the entire post.
What's also very important is where you adjust the post from.
Most modern posts use a remote that you mount onto your handlebars, allowing you to use the post without moving your hands from the bars, which is an obvious benefit when you're riding in rough terrain.
Some cheaper posts are adjusted at the saddle, but I feel it's worth spending the extra cash on a proper remote.
You can often pick the style of remote that you need and there are different versions that can sit under the bar or on top of the bar.
The former is perfect for anyone running a single chainring at the front and also means that you can keep a solid hold on the grip while you use it.
The latter is best if you run multiple chainrings and still need space for a shifter.
Either way, a light, fast action and easy to locate lever is what you need to look for.
Most remotes on the market use a cable to operate them but some, such as the RockShox Reverb, use a hydraulic system.
There are drawbacks and benefits to each. Cables are cheap and easy to replace if they fail but over time they become stiffer to use as dirt enters them.
That isn't a problem for hydraulic units, but they are much harder to fix should you damage one in the field.
The cable itself can be routed externally from the top of the seatpost or internally by exiting the bottom of the post before being routed through the frame to the handlebars.
The former is easier to fit, but the latter is preferable so long as your frame has the routing for it.
Having the cable hidden means it's less susceptible to damage and also won't flap about and catch on your legs or paintwork.
An interesting development has been the introduction of wirelessly operated dropper posts.
As well as getting rid of the faff of cable routing it means you could theoretically have just one post that you use across a number of bikes, assuming they share the same seatpost tube diameter.
The technology is still in its infancy and as such it's very expensive and often unreliable, but it's a matter of time before it becomes more established.
Best dropper posts
Fox Transfer Factory
Fox's second attempt at a dropper post is a resounding success, with super reliable cartridge internals and a smooth, fast stepless design.
There are internally and externally routed designs and up to 150mm of travel on offer.
You get your pick of a 1x specific underbar cable remote or one that works with a shifter, while the micro adjust twin clamp head is super secure and easy to adjust.
As well as this super shiny Kashima coated model (pictured), you can save a bit of cash but keep the same function with the black anodised Performance model.
Thomson Elite Covert Dropper
Long known for its super high-quality seatposts and stems, Thomson brought the same approach to its first dropper post, the Elite, and quickly adapted it to work with internal routing for this Covert model.
It might only have 125mm of travel, but it's extremely smooth and has been very reliable, while the fit and finish is of the quality you'd expect from the brand.
The cable remote works well with most set ups and the stepless design has very little side-to-side play.
If you're running an older frame that takes a 27.2mm post, then Thomson makes a post to fit, though it only comes in an externally routed version.
Specialized Command Post IRcc
Though it's only available in a 30.9mm seatpost diameter, the Command Post is still a decent option thanks to a reliable mechanical actuation.
Unlike many others, it has a stepped design, though the latest model now has 10 additional increments rather than the original post's three settings of 75, 100 or 125mm of travel.
It's also possible to adjust the return speed by adding or removing air to the spring, though the return is on the fast side either way.
The Single Ring Lever bar remote is also excellent, mimicking the shape and position of a SRAM shifter paddle and making it super easy to find and operate.
RockShox Reverb Stealth
Rock Shox’s latest Reverb looks the same but has brand new SKF sealed internals plus long and fat fit options with all the same fully hydraulic pros and cons of previous bikes.
Even with the cunning self sealing Connectamajig plug, removing/intalling the hose can be awkward and while syringes and fluid are supplied, bleeding the post is more complicated than changing a cable if there is a problem.
The plunger doesn’t sit that well with Shimano shifters either, but SRAM’s Matchmaker syncing is superb.
New 170mm stroke and 34.9mm seat post sizes increase versatility and it’s also one of the lightest posts available although it’s heavy on the wallet.
Unfortunately while the pre production posts we originally tested were fine, subsequent early production units have had a very high incidence of assembly faults that have left them bouncing up and down at the top of the stroke. This can be sorted with a rebuild following the correct procedure and QC and SRAM assure us that all new production batches will be sorted before sale.
Budget dropper posts to consider
It might only have 100mm of travel, but the RSP is impressively smooth and sturdy for the money.
The cable remote is easy to use and the cartridge internals have proved to be reliable, if not overly fast to return to full extension.
The micro adjust clamp head does hold the saddle securely and is easy to tweak.
At the moment, only external routing is available, but a longer travel model with internal routing is due to be released soon.
Nukeproof OKLO Air
Though it's only available in a 31.6mm diameter, the updated OKLO is much more reliable that its forebear, though the action is still sluggish, taking a long time to re-extend.
You do also get an internally routed option however and we've found it to be free of play during our test period.
KS eTen Remote
KS makes a number of more expensive posts, but this budget dropper offers up to 100mm of travel with external cable routing.
In common with most budget droppers it's pretty weighty, but it is available in a number of diameters.
The action is a bit sluggish, with a noticeable hesitation as it returns to full extension, but it's the single bolt clamp head that's the major issue, as the amount of layback can really mess with your riding position.