Specialized S-Works Aethos Dura-Ace Di2 review

Aero is everything, according to Specialized. Except when it isn’t.

The Specialized Aethos represents something of a departure for a brand so heavily led by race-focused performance gains. It’s a classically-styled, flagship road bike that serves as an antidote to today’s race bikes. Even to the new Specialized Tarmac SL7.

Whereas the Tarmac, used by the Deceuninck-QuickStep and Bora-Hansgrohe teams at the Tour de France, provides the aero/lightweight mash-up we’ve come to expect from the latest race machines, the Aethos focuses on dropping weight well below what’s allowed by the UCI rule book, without an aero feature in sight.

An obscenely-light 585g frame (claimed weight, size 56cm) is at the heart of the Aethos. The tubes have a subtle conical shape that, according to Specialized, helps balance that low weight with the stiffness expected from a top-end bike, even if the company doesn’t plan for its sponsored teams to use the Aethos.

But more than that, the Aethos is all about the look, too: an understated shape, clean lines, subtle branding. If you’re tired of the homogeneity of modern road bikes – aero this, dropped stays that, integration whatever – the Aethos will be a welcome alternative. Others will likely think, 'Well, what's the point?'

Still, it will be no surprise that the Aethos is a joy to ride. It is a £10,500 road bike, after all, and there's no escaping the fact that is a hell of a lot of money.

For full tech details on the Aethos, and an overview of the range, read our news story. Here I’m going to focus on my first impressions out on the road.

Aero is fast, lightweight feels fast

While aero bikes may be fast, lightweight bikes such as the Aethos feel fast. That’s an important distinction to make and one ultimately guided by a subjective sensation on the road, not objective facts in the wind tunnel. Because let’s be clear, aero bikes are – objectively – very fast.

However, whether it’s the Aethos (6.1kg on our scales) or a similarly-specced featherweight bike, there is little like riding a bike as light as this for the immediacy of acceleration it offers and that direct feeling you get from short, sharp stamps on the pedals.

That, of course, is most evident when climbing. The Aethos excels on steady, consistent climbs, where the pedals tick over reassuringly, but the low weight is most keenly felt on steeper gradients.

The difficulty of any climb will be dictated by its profile and, more significantly, how hard you’re going, but the Aethos makes the job of climbing a faster – and, dare I say it, more enjoyable – experience. Even if you’re deep in the red, it’s a bike that rewards that lung-busting effort. No doubt about it, the rider is the limiting factor here.

I’ve put about 100 miles into the Aethos over the course of three rides, with plenty of climbing in the Mendip hills. One local climb springs to mind. Like many of the ascents around here, it rises in a series of steps. A consistent gradient interspersed by short, sharp pitches, most notably on a steep hairpin knocking on for 20 per cent, near the top of the climb.

It’s a stretch of road that saps the legs on any ride, but the Aethos responds to injections of power on unwelcome rises in gradient by bursting to life beneath you. That’s helped by the rigidity of the frame. The svelte profile and round-ish tubes of the Aethos may lack the beef of more ‘modern’, aero-sculpted frames, but there’s nothing lacking in stiffness.

Fast uphill and back down

It’s a planted descender, too. The Aethos might lack the anchoring effect of a heavier machine but it retains that sense of reassuring stability when the road tips downhill.

Specialized says the Aethos is designed to offer the same fit and handling as the Tarmac SL7, and it’s pin-sharp, as a result. The frame tracks confidently through tight corners and responds accurately to fast inputs when encountering unexpected bends in the road.

I also found the shallow bend of the S-Works handlebar to offer a comfortable position for extended periods in the drops, while also putting the levers within easy reach.

On that note, disc brakes may appear to be something of an oddity on a weight-focused machine like the Aethos – and some riders may still undoubtedly prefer rim brakes on a ‘pure’ climbing bike – but the stopping power and modulation provided by discs is as reassuring as ever.

What’s impressive from Specialized here is that the Aethos’s low weight has been achieved without making everyday concessions. You’ve got those disc brakes, plus a threaded bottom bracket, a seatpost clamp that requires a simple turn of an Allen key, generous tyre clearance and commonly-available, if very expensive, parts.

Moving on and comfort is, well, just fine – it’s not an endurance bike like the Specialized Roubaix, with squishy tyres and suspension, and the Aethos does transmit a bit of buzz through the saddle and handlebar, but it’s nothing untoward at this stage. More time on the bike will be required to see how the frame truly stands up to long rides on rough roads.

Specialized specs 26mm tyres as standard but I’d be keen to try 28s or really exploit the maximum 32mm clearance to see how the Aethos rides as a super-light road bike, with an endurance (or, dare I say it, gravel-adjacent) slant, though you’ll give up some weight in the process.

However, if you want to run tubeless tyres, you’re out of luck. The Roval Alpinist CLX wheelset specced on the S-Works Aethos is very light (1,248g claimed weight) and very stiff, but not tubeless-compatible. Like the S-Works Tarmac SL7, Specialized is once again backing clinchers here.

Old-school new

If you’re a rider driven by cast-iron performance gains – watts saved over 40km, CdA, that kind of thing – the Tarmac is not only likely to be the faster bike in the majority of scenarios, but the most appealing.

There’s no getting past the physics of it, but we buy and ride bikes for all manner of reasons, and how they make us feel while riding is one of them. In reality, for many of us, it's the most important reason. There is something undoubtedly raw and rewarding about riding the Aethos.

You’re buying into its, ahem, ethos and aesthetic, too. Some will hate the fact it has a five-figure price tag yet shuns many of the latest innovations – no integration, an old-school seatpost clamp, exposed cables! – but others will love the shape of a frame that turns back the clock, while providing a ride that still points to the future.

Specialized S-Works Aethos Dura-Ace Di2 early verdict

The Specialized Aethos combines classic styling and everyday practicality with ridiculously low weight and a superb ride... at an almighty price.