Over the summer, FSA quietly debuted a new 27.2mm Flowtron AGX dropper post for XC & gravel bikes as part of their ‘coming soon’ 2021 component line-up. Now, that 100mm travel gravel bike dropper is available. So we took a first look at the internally routed Flowtron AGX setup, weighed it in, and installed it on a bike to head off-road for some dropbar trail riding…
FSA Flowtron AGX 27.2mm, 100mm gravel dropper seatpost
The first question you have to ask when someone says “gravel dropper” is obviously… why? Do you really need a dropper post for gravel bike riding? The answer to that is probably no, but then again… maybe, why not!
If you are like me, and often ride dropbar bikes beyond the edge of normal people’s comfort zone, a dropper seatpost can be great for sketchy technical descending. Keep your saddle up high for efficient pedaling & climbing, then drop it like it’s hot when you get in over your head.
And of course, a 27.2mm diameter dropper with 100mm of travel isn’t limited to a gravel bike. FSA sells the same Flowtron setup with a flat bar remote for your mountain bike. I chose to drop it into my trusty old custom lugged steel singlespeed cyclocross bike. Because, as I said… why not!
Next question about a ‘gravel’ dropper is whether it will actually fit. To fit this 100mm travel dropper in your bike, you’ll need at least 164mm of seatpost sticking out of your drop bar bike, measured from the saddle rails to the top of your seatpost clamp.
FSA lists minimum & max insertion depths, but more importantly… 164mm is a lot of exposed post for a gravel bike or any dropbar bike really. None of the four gravel bikes floating around in our shop right now have that much post showing. Another reason the SSCX bike got it.
Dropbar dropper remote & post details
Drop bar dropper remotes are still quite new to the scene. There are a few general options, and the FSA Flowtron AGX setup opts for a large lever that mounts just under your shift/brake lever body, on the inside of the left hand drop.
The Flowtron AGX drop bar mount is intended to be usable with your hands on the hoods or in the drops. Actual lever throw is quite long in the end, requiring a wide range of motion in the thumb & wrist from either position. But I was able to set it up so I could actuate it from both hand positions. It is easier from the hoods, though.
The Flowtron AGX dropper post is actuated by a shifter cable, with the ball-end at the base of the post. So the cable is clamped at the remote, with a grub screw under the lever.
It’s a little trick to install actually. Remember that we’re talking about an internally routed post, and with a cable that is routed on your dropbar under the bar tape. It’s important that you figure out the sequence of operations.
You have to completely remove your bar tape to install the remote, first. Then you have to figure out (estimate/calculate) how long the cable needs to be with the dropper set to the correct saddle height, and the cable routed internally, with the perfect length of cable loop exposed.
Ideally with the remote removed from the bar, you can tighten & adjust the cable. An inline barrel adjuster makes fine-tuning easier. Then install the post into the frame and pull the housing into place, before you put the remote back on the bar and re-wrap the tape. With a smaller loop of housing exposed than on a mountain bike (because you wrap it under the bar tape), it really is a more tricky and sometimes frustrating process.
The Flowtron post itself uses a 3-bolt head, with independent adjustment & 15mm offset. A bolt on either side clamps the rails in place, and works with round or oval rails. And the last bolt secures saddle angle. You can also set the post to 0mm offset, by flipping the head AND rotating the entire post 180° in your frame.
The main seal assembly has a relatively compact 20mm stack height, including a chamfered lower edge which keeps it from being slammed all the way against your seatclamp. (See the little silver bit where I scratched it against my seat lug above.)
The actuator at the bottom of the post also has three positions to adjust the return spring, so you can fine-tune remote lever feel a bit.
XC or Gravel dropper – Actual weights
FSA claims a weight of 500g for their 27.2mm diameter, 100mm travel Flowtron AGX dropper. There are a number of shorter travel & lighter 27.2mm droppers on the market, but at least our actual measured weight is pretty much dead on to FSA’s claim.
Talking about how much the full install will weigh when you put it on your gravel, cyclocross or bikepacking adventure bike… the Flowtron AGX dropbar remote adds another 42g, plus another 83g for full length housing, inline adjuster & cable end.
2021 FSA Flowtron AGX dropper – Pricing & availability
The 100mm travel Flowtron 27.2 dropper comes in just two versions – XC with a flat bar remote or AGX with this drop bar remote. Both retail for the same $249 / 249€ price, including post, remote & cables.
Officially a 2021 product, FSA says they are on the way to all global distributors right now, and will be available in consumers hands in a matter of days. The post carries a standard 2 year warranty, and replacement sealed IFP cartridge & seal assemblies are available for servicing the dropper.