Review: Bontrager Drop Line Dropper Seatpost

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Tom Hill takes us through the Bontrager Drop Line dropper post after eight solid months of testing.

‘Up, down, turnaround, please don’t let me hit the ground,’ sang New Order, documenting their troublesome relationship with dropper seat posts. Over years of testing, I’ve experienced ‘uppy downy’ posts that have done pretty much all of the above – spinning 360º, developing play, sinking or remaining fixed when not wanted. I’m not sure if I’ve ever hit the ground as a direct result, but the bike probably has done in moments of frustration.

bontrager drop line dropper seatpost cotic flaremax tom hill
The Drop Line is the first dropper seatpost from Bontrager.

While few would argue that dropper posts are now perfect, there is doubt that reliability is improving, as is the range of choice from manufacturers that have, perhaps wisely, stood back and observed the early years of development.

bontrager drop line dropper seatpost cotic flaremax tom hill
Neat paddle-style remote that’s specific for 1x drivetrains. Bontrager offers a universal remote too.

Perhaps in response to increased consumer demand and expectations when it comes to off-the-shelf bike builds, Trek’s component arm, Bontrager has developed its own dropper post. You’ll see it specified across Trek’s range this year, but it is also available to the masses. Coming in three flavours of drop; 100mm, 125mm and 150mm, but just one seatpost diameter (31.6mm – the same that you’ll find on all Trek frames).

bontrager drop line dropper seatpost cotic flaremax tom hill
In a move that’s much appreciated by us, the Drop Line routes its actuation cable with the cable nipple  at the base of the post.


Trek sent me the 125mm version, neatly packaged and ready to fit. All of the Drop Line posts are ‘stealth’, and designed to be internally routed. Fitting was surprisingly straightforward. Whether this will apply to you will depend somewhat on the dropper routing on your frame, but Bontrager does what it can to help.

bontrager drop line dropper seatpost cotic flaremax tom hill
Easy to remove.

The post is cable actuated – no messy hydraulics to worry about, or bleeding required. Unlike some droppers, the Drop Line locates the pinch bolt of the system at the much easier to access lever end. At the seatpost end, the cable nipple sits in a barrel which slots neatly into place, and is easy to free, making it much easier to remove the seat post if necessary, and to adjust cable tension once the post is fitted.

bontrager drop line dropper seatpost cotic flaremax tom hill
The pinch bolt is found on the backside of the lever paddle. Preferably secured with a cable end…

At the other end of business, the cable is clamped by a grub screw (which I promptly lost, so replaced with a something suitable from the spares box) at the lever. Cable tension is adjusted in much the same way as a gear shift, via a barrel adjuster on the lever body. The lever itself is a lovely, ergonomic thing, working best below the bars on the left hand side – perfect for 1x users. Bontrager also offers a universal lever, for a modest £14.99, giving a better range of fitting choices for those who prefer to run a front mech still.

bontrager drop line dropper seatpost cotic flaremax tom hill
I’ve been testing the Drop Line seatpost on my personal Cotic FlareMAX. And she’s been through some serious riding over the past eight months.

The Ride

The first couple of months with the Drop Line were notable only in that there was little to note. There are no quirks to the post, little to get used to. It functioned as you would expect and just played nicely. Personally, I would have preferred a little more drop – the 150mm version would have been ideal {but then Tom IS six foot – Ed}. There were a few times that even with the saddle slammed, I’d have liked to get my bodyweight that bit lower. This tended to be on the steepest, techiest trails though. For day-to-day riding, 125mm was ample and it is hard to criticise when Bontrager sells a longer travel offering.

bontrager drop line dropper seatpost cotic flaremax tom hill
In action, the Drop Line post works well, but I would prefer the 150mm travel option.

The lever is the best feeling, most ergonomic that I’ve ever used. Period. And in conjunction with smooth travel at the post, it was easy to set the saddle exactly where I wanted it, anywhere between fully compressed and extended.

bontrager drop line dropper seatpost cotic flaremax tom hill
The 1x remote is the most ergonomic of any dropper post I’ve used.

I should probably mention that while this was in the middle of autumn, it was a particularly dry period, and included a week of riding dusty trails in Spain. Then winter hit. Before my tan could even fade, I was flung back into more traditional sloppy UK conditions. Things were pretty grim, in fact. Copious quantities of mud, grit and water have been slung at the Drop Line. It didn’t enjoy it. After a handful of thoroughly grotty rides, things started going rapidly downhill, over the course of a ride. First off, the post became slow to return, then any movement was accompanied by a gritty, crunchy soundtrack. Finally, the post stuck in position, only shiftable via an odd bouncing up and down, grabbing the saddle nose with one hand, and the lever with the other. Sub-optimal, I believe the saying is. Time for a service, eh?

bontrager drop line dropper seatpost cotic flaremax tom hill
With eight months of riding under my belt, the Drop Line has seen some pretty wet and filthy conditions.


Fortunately, a strip and clean of the post is an easy process. Sadly, there aren’t any online guides (yet). A few allen keys will allow you to remove the outer sleeve, clean out all the unwelcome gritty guests and re-grease. I found a fairly loose grease, like SRAM Butter or Slick Honey best.

Once practiced, the process probably takes 10 minutes. I’d argue that it is something that shouldn’t need to be done, at least not quite so regularly. In eight months of riding, I’ve now gone through the service process twice now (and a couple of quick squirts of Slick Honey under the collar in the meantime), and the signs are there that another is due. In my eyes, this problem would be solved by better sealing around the outer collar.

bontrager drop line dropper seatpost cotic flaremax tom hill
Servicing is relatively easy, but it appears that the main seal on the threaded collar is a little too free, and lets a lot of crap in.

Curious as to whether I’d got a duff seal, I had a chat with a few fellow testers and riders. A few Trek test bikes have passed through Singletrack Global Headquarters recently. As you’ll read in Wil’s review of the 2017 Trek Fuel EX 9, all of the Drop Lines we have experienced have sadly suffered the same fate. And I’m aware of others.

Interestingly, Aussie-come-Todmordian Wil checked with a few former colleagues Down Under to identify if the same issue had been uncovered elsewhere on the planet. As it turns out, they’ve had no issues in drier climates.

In cold conditions under 6°C, the post also seemed noticeably slower to return. It was hard to distinguish between the effects of the cold and any ingress of grime, but as temperatures warmed up and the trails stayed wet, performance has improved slightly. My guess is that the post is very sensitive to the viscosity of the grease used. My first servicing attempt used a thicker general purpose grease, with similar sloooooow motion consequences.

bontrager drop line dropper seatpost cotic flaremax tom hill
The anodizing on the back of the Drop Line has started to show signs of wear.

Longterm Durability

The Drop Line is beginning to show some longer-term symptoms of wear – largely as a direct consequence of the seal issue. The black anodising of the stanchion is wearing in places and the post action isn’t quite as smooth as it once was (although perfectly functional). There is also a fair amount of play at the saddle – not far off 10mm in either direction at the tip of the nose. It isn’t really noticeable when riding in the saddle, but actually rattles when out of the saddle, which is enough to drive an obsessive crazy. Fortunately I’m not as obsessive about these things as some (I’m looking at Wil here), but it’s pretty damn annoying.

bontrager drop line dropper seatpost cotic flaremax tom hill
While it’s easy to service, I’d like to see tighter sealing used to minimise the requirement for regular servicing in the first place.

As winter has given way to spring, and the trails have transformed into the zippy, dusty tracks of my dreams, the Drop Line has remained on the bike, despite its foibles. It is far from being the Holy Grail of droppers, but it is so close to being a great product. Yes, the repeated maintenance is frustrating, and no the post doesn’t feel UK proof at the moment, but there have been no larger mechanical failures. The real meat of the post has done its job impeccably, and if anything, it’s proven to be easy to service too. Which is more than can be said for a lot of other dropper posts on the market.

bontrager drop line dropper seatpost cotic flaremax tom hill
If you don’t ride in filthy conditions, the Drop Line is likely to work as intended, and the ergonomic remote will please all who touch it.

The Drop Line is considerably cheaper than many top-end droppers’ RRPs. For example, the latest RockShox Reverb dropper will set you back £375, while the new KS LEV Ci runs between £480 – £540. But no matter what language you speak, £240 is still a whole lot of money, and I’d expect a few years’ use (with an appropriate level of servicing) out of that.


So close, yet so far. A potentially great product if you live somewhere dry. If you live in the UK, be prepared for a meticulous and regular maintenance regime.

Review Info

Brand: Bontrager
Product: Drop Line Dropper Post
From: Trek Bikes,
Price: £239.99
Tested: by Tom Hill for 8 months

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