In this Dust-Up, Travis claims 27.2 mm seatposts are symptoms of the gravel industry’s refusal to evolve. Turns out there’s more to it, but he’s still upset.
This whole beef started a couple years ago when I was shopping for my first dedicated dirt touring bike. The Salsa Cutthroat was everything I wanted. Boost spacing, carbon frame, huge tire clearance, and a huge-er front triangle. But its 27.2 seat tube drastically thins the herd of compatible dropper posts. Sure, there are decent 27.2 droppers out there, but their travel seems to be capped at around 125 mm or less. Go ahead and @ me if you know of a longer one, but I’m skeptical. Even full-girth droppers need semi-regular rebuilds to address friction buildup and prevent bushing wear. I don’t like the idea of stepping down the inner diameter any further. I’d just rather my frame have a 30.9 or 31.6 seat tube.
That’s why I ended up with an Otso Fenrir and a 170mm RockShox Reverb. Some folks would say that much travel isn’t necessary on a drop-bar bike. I totally agree. But my utter disdain for that word, “necessary,” is a topic for another dust-up. A topic for this dust-up is that long droppers are uniquely valuable on off-road drop-bar bikes.
I’m in the drops on most descents, technical or not. With my 170 mm dropper, my neck is more comfortable, and my weight distribution is more even. I wrote about this in my review of the YT Szepter after I swapped its stock 75 mm AXS XPLR dropper for the 170 mm AXS dropper that the bike deserved.
And that was only possible because YT specs the bike with a 27.2-to-30.9 seatpost shim. I hoped this would be a sign of things to come, but otherwise progressive bikes keep dropping with 27.2 seat tubes.
The new Santa Cruz Stigmata, like the YT Szepter, seemed like a perfect opportunity for a mountain bike brand to make a gravel bike for a mountain bike customer. There are suspension builds, 1x builds, and even SRAM Transmission builds, though that last one only appears in the marketing videos. But the seat posts and seat tubes are 27.2 across the board. I reached out to Peter Mueller-Wille, Senior Design Engineer at Santa Cruz, and he made a pretty matter-of-fact case for their approach.
“We found that there is a significant difference in stiffness (vertical compliance) between a 30.9 and 27.2 seatpost by itself,” Mueller-Wille explains. “But that is then compounded when assembled into a frame with correspondingly sized seat tubes. Larger diameter means increased stiffness for both the post and the frame tubes.” I heard similar versions of the comfort argument from all the 27.2 devotee brands I spoke with. Joe Meiser, Category Manager at Salsa Cycles, elaborates further regarding the process of weighing consumer demand in a bike’s early development.
“When designing a bike, the team evaluates how prevalent dropper posts will be in spec or as an aftermarket upgrade,” Meiser says. “Riders that work for Salsa love droppers on their drop-bar bikes (I have one on my road bike!). Fortunately, great 27.2 options exist! Salsa can continue to provide the comfort that 27.2 ‘rigid’ posts offer for most riders while continuing to provide compatibility with droppers.”
And about those 27.2 droppers: I had assumed there was some sort of fundamental, material limit on how long you can reliably stretch one to be. But as John Staples, co-founder of OneUp Components tells me, it’s not that simple.
“We haven’t tested [150-180 mm] lengths yet,” Staples reveals. “We suspect it’s possible to develop a long-travel dropper within the confines of a 27.2 post. However, the use case is pretty slim, especially as 27.2 frames become less common.” In other words, dropper-post manufacturers are sticking with short 27.2 posts for much the same reason gravel-bike manufacturers are sticking with 27.2 seat tubes: Not enough riders are actually asking for anything to change.
I drilled down on this with another brand that swears by 27.2 posts on their drop-bar bikes: Marin. If the Salsa Cutthroat was the seed that first inspired this story, the Marin Gestalt X10 was the watermelon through the windshield that convinced me to finally write it. The Gestalt X10 seems to have been patterned after the Evil Chamois Hagar.
They’ve got a similar silhouette and a similar set of geometry numbers. But the Chamois Hagar launched over four years ago, and had no singular established source for inspiration. That bike sent shock waves through both the mountain and gravel worlds. It challenged what we thought was possible or practical in drop-bar bike design. It also came specced with up to a 170 mm 30.9 dropper post.
But the Marin Gestalt X10 is less than ⅓ the price of the Chamois Hagar. It has the potential to broaden access to aggressive drop-bar bikes. To short-circuit the circular argument that riders who want both drop bars and capable geometry is a niche market, and will thus only ever be served by niche brands.
Nevertheless, Marin gave the Gestalt X10 a 27.2 mm seat tube just like their far more traditional gravel bikes. And a shallow seat tube at that, thanks to a cutout for tire clearance. According to Aaron Abrams, Director of Product at Marin, their data simply doesn’t support breaking the mold to suit thicker, longer dropper posts.
“We at Marin were one of the first brands to spec a dropper post on a drop-bar bike,” says Abrams. “And it has not been a universally applauded thing on those bikes.” Apparently, when Marin tries to push the market towards dropper-post adoption, the market often pushes back. “On the Gestalt X, people seem to get it. But on our carbon gravel bike, I still get questions of, ‘why did you put that on there?’ The higher-end riders end up taking it off, saying it’s just extra weight.”
This feedback comes through several channels. Directly from dealers and athletes, but also by observing through social media how people are customizing their Marins. Riders just aren’t clamoring for dropper posts, much less for longer ones. Or rather, most riders aren’t.
“There’s a certain percentage of what we would call ‘gravel riders’ who are coming from the mountain bike side, but it seems that most are coming from the road side first.” I guess that tracks. For every shred edit of a gravel bike on singletrack, there are a thousand beauty shots of two friends in minimalist kits pounding out the fire-road miles. “Those riders don’t feel that droppers are necessary, and they’ve lived this long without them.” There’s that word, “necessary,” again.
But I guess I can’t argue. Abrams even poked some holes in my case for seatpost shims as the ultimate compromise. “Shims are always a recipe for problems between creaking and slipping,” he explains. “And dropper posts accentuate that stuff anyway. You’re putting all of your weight on it and slamming over and over again.”
I must admit that using a shim can be a bit of a pain. I actually use one in my Fenrir because I didn’t want to buy an $800 31.6 AXS dropper if there’s a chance I might eventually swap to a 30.9 frame. Even though I don’t think about it 99.9% of the time, sometimes I do have to fight the shim when repositioning my post.
But YT, who specs a shim in the Szepter, has apparently had no problems. “The issue is to find the right one,” Reynaldo IIagan, YT’s VP of Product Development told me. “If the shim is too stiff, clamping of the seatpost can be an issue.”
That makes sense. A 27.2-to-30.9 shim isn’t a pop can. It’s actually a pretty burly hunk of two-millimeter-thick aluminum. Though, that presents its own problems. “Only thing where we had internal concerns was aesthetics. Because the jump in diameter of the seatpost to seat tube is bigger compared to a ‘normal’ spec. And it adds a bit of weight, but the bike was not designed to achieve weight records.”
After talking to brands who are much more established in the mainstream gravel world, it became very clear to me that YT’s approach isn’t going to be embraced as the sliver bullet I hoped it would be. Aesthetics and weight—next to compliance and tradition—probably make up the top four reasons mainstream gravel isn’t ready for disruptions like introducing long-travel droppers.
So, at least for now, the fringe will have to lead the way until the mainstream catches up. I chatted with Zach Small, founder of Amigo Frameworks, who made Josh’s Bug Out drop-bar bike. It’s sort of a more businesslike version of my Fenrir. It’s not quite as MTB-adjacent, but the tires are wide and the angles are aggressive.
“Most gravel bikes are actually road bikes, in my opinion,” Small argues. “Oh, they’ve slackened the head angle to 70 degrees from 72, but I don’t feel that significant a change, especially if you consider that the front-center isn’t that different.”
Small spent much of our call on tangents about frame geometry and how various norms were established in various categories, but I had to keep steering him back to seat tubes. The Bug Out fits a traditional-sized dropper post, but not only because they make ’em longer.
“The reason why I use a 31.6 seatpost is that the internals are nice, the volumes are larger, it makes the dropper work way better than anything smaller. I don’t want to compromise on such an expensive part,” Small explains. “And you’re on a bike with big tires. A lot of your compliance is going to come from that.”
Before I talked to Small, I was feeling kinda defeated. I’m not sure what I expected to hear from the other brands I talked to, but I guess it was something like: “WE decide what a drop-bar bike can and cannot be. Not you. Not our customers. US!” Unfortunately for this story, the truth isn’t nearly as cartoonish.
Maybe most drop-bar customers truly would not get the experience they’re after if more bikes had larger-diameter seat tubes. Maybe it’ll always be up to the outliers to serve the statistical minority who are stepping into the gravel world directly from the mountain bike world.
Or maybe it’s just going to take time for the mainstream to catch up. I see a lot of similarities between gravel biking in 2024 and mountain biking in 1994. One discipline overwhelmingly dominated during mountain biking’s steep and sudden rise in popularity: XC racing.
The majority of bikes on the market reflected that, regardless of what people actually wanted to do with them. It would be more than a decade after that XC-forward period before consumer-friendly geometry made a widespread return in the form of “trail” and “all-mountain” models. XC bikes have steadily faded from popularity, but will still be around for a very long time.
Gravel bikes will be around, too. But inevitably, subcategories will emerge, arise, and perhaps even overtake the style that sparked the boom in the first place. Though, by the time that happens, my diameter of choice will probably have shifted from 30.9 to 34.9.
If you’re new to this series, welcome to The Dust-Up. This will be a semi-regular platform for Radavist editors and contributors to make bold, sometimes controversial claims about cycling. A way to challenge long-held assumptions that deserve a second look. Sometimes they will be global issues with important far-reaching consequences; other times, they will shed light on little nerdy corners of our world that don’t get enough attention.
