Specialized S-Works Aethos review

The Aethos climbs like a race bike, feels like a race bike, is modeled after a race bike, is as light as a race bike — but it's not a race bike.

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Photo: Brad Kaminski

Review Rating


New carbon layup; no dropped seatstays; threaded BSA bottom bracket; power meter included


Extremely light; very stiff; excellent handling; cool paint


Extremely expensive; not much compliance

Our Thoughts

The Aethos gets 4 stars because of its price tag. Otherwise it would easily earn a 5-star rating.

Size Reviewed



13.6 pounds





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The Aethos is not a race bike. No, really. All of Specialized’s marketing on this one says it’s for the performance-oriented rider, but not necessarily for racers. Crush your KOMs! Go on all-day epics! Climb like a boss in your non-team kit! This one’s all about the ride experience!

It’s lighter than the UCI’s 6.8kg minimum — at 13.6 pounds for the test model I have been riding — and it has a threaded BSA bottom bracket. And look at that classic silhouette, without a dropped seatstay in sight.

But that’s really the only three things that make this “not a race bike.” The Aethos is excellent and super-fun to ride, but it’s hardly an everyman’s bike. The price tag certainly reinforces that notion.


Aethos DNA

The Aethos features an all-new carbon layup that Specialized says eliminates reinforcement carbon that otherwise would add weight to the frame. That all has to do with the frame’s uninterrupted lines, which allow for larger and longer unbroken plies of carbon. For example, on a bike like the Tarmac SL7, the junction where the dropped seatstays meet the seat tube will need reinforcing, because carbon fibers don’t like sharp angles. The more traditional silhouette of the Aethos allows for more continuous lines without such sharp junctions.

Specialized S-Works Aethos
The Aethos features a classic silhouette — no dropped seatstays here. Photo: Brad Kaminski

On top of saving weight, Specialized engineers hoped to increase stiffness. Usually the latter runs contrary to the former here, but Specialized came up with a barrel-shaped head tube that helps efficiently transfer loads to the down tube. That down tube is thicker at the head tube junction and tapers down toward the bottom bracket. The result, presumably, is sharp steering and solid handling characteristics.

head tube
Specialized says the head tube on the Aethos is slightly barrel-shaped to provide “the best possible load transfer” to the down tube. Photo: Brad Kaminski

The down tube and top tube are both larger at the head tube junction, and taper as they run down the frame. Specialized says this helps stiffen up the ‘spine’ of the frame Specialized told us that there’s a lot more torsion in the head tube and down tube than designers thought previously. As a result, the tubes must be fat at the front, and tiny in the rear at the top tube and the down tube.

Specialized went deep into the simulation cave to arrive at that conclusion. There were more than 100,000 run, and Specialized developed its own software to hone the possibilities down to about 25 before actually laying up frames to test. It was, as Specialized reps said, “a data monster.”

From there, Specialized  focused on optimizing the frame’s joints so stresses flowed through very smoothly. That meant engineers could eliminate stiffness fibers, which add weight, because of the shape and the continuous lines that eliminate junctions and angles.

The thickness of the tubes, however, aren’t smaller. They are, in fact, about the same thickness as the Tarmac SL6, but the tubes are also smaller overall. That’s partly where the weight reduction comes from. And the unique tube shapes, Specialized says, translates into extraordinary stiffness.

Continuous fibers
Photo: Brad Kaminski

In true Specialized fashion, the Aethos culminates in the finest details, like the thru-axles, which have been redesigned to save about 15 grams. The material around the conical head was essentially shaved down to accomplish this. It’s clear the Aethos engineers didn’t miss any opportunities to make this bike light enough to make it a conversation piece.

Aethos bottom bracket
The Aethos features a threaded BSA bottom bracket. Specialized says a T47 bottom bracket didn’t offer any advantages in terms of weight savings or stiffness, so it stuck with BSA. Photo: Brad Kaminski

Notably, however, Specialized doesn’t mention much about aerodynamics in the Aethos design. It’s all about weight and stiffness instead. That’s an interesting choice, given that more and more data indicates aerodynamics benefits the vast majority of riders, even on climbs. So it’s a bold choice for Specialized to buck that trend, presumably in the name of ride quality over speed (which is generally the opposite of race bike design). Clearly Specialized wants you to enjoy the ride above all else, even if that means sacrificing some speed.

That also becomes clear when you look at the more traditional two-piece cockpit; no integration here, and no flat-top bars in a nod to aerodynamics. The cockpit, which incidentally is very comfortable, is all about adjustability, comfort, and light weight.

Tire clearance
The Aethos has clearance for tires up to 32mm. Photo: Brad Kaminski

To appeal to a wider swath of riders, the Aethos has clearance for tires up to 32mm. That means you can do a bit of ‘all-road’ riding, and also take advantage of the lower rolling resistance and comfort aspects of wider tires at lower pressures. The Aethos is disc-brake-only, which shouldn’t come as much of a surprise.

Understated logos
Specialized says the understated logos are all part of the Aethos story. Its classic lines and simple graphics appeal to everyday riders rather than sponsored athletes. Photo: Brad Kaminski

The lack of large logos was a purposeful decision too. The ‘everyday’ rider appreciates a beautiful bike, something they can show off at the coffee shop. The logos on the Aethos are almost non-existent save for a small word mark on the fork blades, another on the top tube, and a logo on the head tube. The rest of the bike is devoid of logos, which shows off the complex and beautiful paint job nicely.

From far away, the Aethos looks plain, and almost looks black. Up close, the paint has depth and sheen that make it interesting and fun. Photo: Brad Kaminski

The top of the line Founder’s Edition is pretty exclusive — there will only be 300 bikes available globally, and each one will cost $14,500. It’s also the lightest bike in the entire Aethos lineup and features a unique Brushed Silver paint job. The S-Works Dura-Ace Di2 and SRAM eTap AXS versions cost $12,500. The S-Works frameset will run you $5,200.

The Aethos will be available in a ‘Jet Fuel’ colorway, which is the lightest option. You can also get topographical decals that can be pulled off without sanding, allows you a complete canvas to repaint your frame if you want to go totally personalized. Best of all, removing these decals won’t void your warranty.

Aethos first ride

The Aethos on Flagstaff Mountain
I rode the Aethos on some tough climbs here in Colorado, including Flagstaff Mountain outside of Boulder. Photo: Brad Kaminski

Back in 2006 I was working in a bike shop in Arizona, and a customer asked us to build the lightest bike possible, cost be damned. So we did; it weighed just over ten pounds — and it was awful to ride. It was flexy to the point of jittery, and it felt like it could break at any moment.

The Aethos suffers from none of that. It feels solidly built and I had no hesitations really cranking on it. In fact, I found the Aethos to actually be a bit stiffer than I expected — and stiffer than I would have preferred. Compliance falls to the 27.2mm seatpost, and you can certainly feel it pivoting when you hit something big. But the Aethos actually does transmit a fair bit of road noise to the rider. It wasn’t exactly bothersome, just noticeable.

I like riding the Aethos quite a lot — I mean, like, a lot — but as someone who spends almost all his time on race bikes, that shouldn’t come as too much of a surprise. And let’s be honest: The Aethos is indeed a race bike, rebranded and with fancy marketing to tell you otherwise. It’s entirely possible, in other words, to “just ride” on a race bike, and it’s entirely possible to race with the Aethos.

Two out of my three initial rides on the Aethos were on substantial climbs here in Colorado, and the bike immediately feels like other wispy climbing bikes I’ve ridden. It’s lithe, fun, and stiff underfoot. It’s a ripper on descents, though I did notice that the steering doesn’t feel quite as sharp as the Tarmac, even though the geometry is identical. I wonder if that’s a result of stiffness numbers rather than geometry here, or if it’s just in my head. The two bikes aren’t far off in that regard, but it was a noticeable difference.

I absolutely crushed a PR on one climb I do frequently, which is only anecdotal support of this bike’s capabilities. But feel certainly counts for a lot.  The Aethos shines when you’re climbing out of the saddle, and on this particular segment, all I wanted to do was coax the bike a bit more, and it was more than happy to oblige. I suspect with deeper-section wheels I could take another crack at this segment, which isn’t particularly steep, and possibly shave a few more seconds.

So far I’m not buying into the, “this isn’t a race bike” marketing pitch, especially given the sky-high price tag, but I am indeed buying into the bike as a whole. It’s fun to ride, it’s lithe and fast, it’s super light, and it looks very cool with the minimalist logos and gorgeous paint.

I love that I can adjust the cockpit, too. As more race bikes come stock with integrated systems, I find myself appreciating a good ol’ fashioned stem that allows me to loosen some bolts to adjust the bars quickly and easily. I’ll take a knock in the aero department for that.

The Aethos is a testament to how far frame technology has come since my days as a wrench in that Arizona bike shop in 2006. Unfortunately, it’s also a testament to how far price tags have grown. If Specialized truly wants to make this a bike for everyday riders passionate about the ride, the Aethos would cost about a quarter of its current price tag. That said, this bike surely is something special. If you’ve got the coin, the ride certainly is worth it. For the rest of us, we’re still on the outside looking in at exclusive product that would undoubtedly be perfectly at home on the racecourse.

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