When Specialized launched the original S-Works Aethos at the end of 2020, it broke all the rules. It was almost counter cultural in its rejection of the contemporary race bike, and the timing was perfect. All the major brands, including Specialized itself, had spent the previous decade developing race bikes that were more aerodynamic, more integrated, more aggressive and which weighed no less than 6.8 kilos – but it was clear that not everyone wanted that. So the Aethos was created solely to deliver a beautiful ride instead of satisfying racers and UCI rules: to “reward the rider who doesn’t pin a number on, but who instead seeks the raw sensations and pure enjoyment of a perfect ride.”
The result was an anarchically light 5.9kg bike with round tubes, external cable routing, a standard 27.2mm seatpost and a threaded bottom bracket. The classic aesthetic and minimal branding gave it a simple elegance. Its ride quality matched its looks. It was universally lauded.
It took me four years to ride one, but I finally did, in 2024, primarily for the purpose of reviewing the new SRAM Red AXS, and it was even better than I thought it would be. I described “almost magical lightness”. You had to ride it to believe it. To complement the new groupset, Specialized built up a limited edition ‘glacial metallic’ frame for me with Roval Alpinist CLX II wheels, S-Works Turbo 28mm tubeless tyres and an S-Works Power with Mirror saddle. It had a Roval Alpinist alu stem and S-Works carbon bar. It was a dream build for a dream bike – perfection.
Five years on from the launch of the first bike, Specialized has unveiled the Aethos 2. The strapline is “Break the rules. Again”. The US brand says it has made the bike “more perfect for more riders” and has refined the geometry, increased tyre clearance to 35mm, equipped it with new Roval Alpinist components and made what it calls “subtle but significant improvements”. The things that haven’t changed are the weight – Specialized says the S-Works Aethos 2 is still the world’s lightest disc road frame at 595g (this looks like an increase of just 10g) – and it promises the same sublime, responsive ride with intuitive handling that riders originally fell in love with.
Stabler geometry
Whereas the original Aethos’s geometry was lifted straight from the Tarmac SL7, the pro race bike at the time, for the Aethos 2 Specialized has created bespoke measurements that it says were informed by 100,000 Body Geometry fits, tuning the bike for comfort, stability, and performance without sacrificing the “telepathic” handling. This entailed adding 15 mm of stack to the four of the six frame sizes (the 49 cm frame gains 8mm of stack, and the 52 cm gains 11mm). The head tube angle has been slackened by 0.5 degrees, and the bottom bracket lowered by 3mm.
The wheelbase is also 7mm longer. These all look like logical changes that bring the new Aethos in line with current bike fit thinking. We’ve seen higher stacks across the board for the latest generation of endurance bikes that are not designed for racing such the new Scott Addict, Factor Monza and the Basso Sempre Veloce – comfortable for longer rides with less pressure on the hands. The longer wheelbase and slacker head tube angle (though still 73° in the size 56, which is not overly slack) are aimed at increased stability at speed and smoother control. Lowering the bottom bracket lowers the centre of gravity for better cornering, but in this case it will most likely be designed to cancel out the extra height of running bigger tyres than before – which leads to the next update.
More tyre clearance
Updating the tyre clearance from 32mm to 35mm is another necessary step. Nowhere in Specialized’s press release is all-road, mixed terrain or gravel mentioned – the Aethos is still 100% a road bike – but with many race bikes running 30mm tyres now, everyday road riders expect even more. More clearance necessitates more material, and this presented its engineers with a challenge, which Specialized documents in the press release. To build in the extra clearance without increasing the frame weight it was necessary to rework the frame’s carbon layup and “refine each ply by fractions of a millimetre”. Specialized calls this Flow State Design: “By optimising shape instead of adding material in layering stiffness, we eliminated traditional ‘stiffness’ layers of carbo- fibre. The outcome is a lighter frame with better ride quality, improved structural integrity, and real performance gains.” However, the finished frame is not fragile. The brand says it’s durable and robust and has survived testing well beyond industry standards.
The S-Works Aethos 2 frame is made with Specialized’s top 12r carbon, the one with the claimed weight of 595g, while the Pro and Expert frames are made with 10r carbon and weigh a claimed 705g (size 56).
Contributing to the low weight are a redesigned seatpost clamp (9g lighter than before), brake mounts (-2g), BB cups (-6g) and a custom UDH derailleur hanger (-2g). Specialized claims the Aethos 2 is still the world’s lightest disc road frame, and these lighter components help deliver complete builds that are lighter than previously with the ‘Pro’ and ‘Expert’ lower-tier builds.
New integrated cockpit
There will be so-called purists who don’t like that the brake cables are now internally routed through a new Roval Alpinist II cockpit and directly into the head tube, but five years is a long time in bike development and integration is arguably now expected with a bike at this level. It would even be a strange, retrograde step if Specialized had kept cables external with the Aethos 2. I’m not going to do the whole argument here, but if you can set up a bike to your bike fit measurements from the start – the Roval Alpinist II comes in 13 size options so it ought to be possible – and your headset bearings are good quality and properly adjusted, how often do you really need to dismantle the cockpit? There’s no argument that integration cleans up the front end, and for me it makes the Aethos look even better. However, the 1 1/8in steerer is compatible with standard stems for those starting from the frameset and doing a custom build. Indeed the ‘entry level’ Aethos Expert does come with a separate bar and stem – cables are still routed inside the head tube.
Roval's lightest ever wheels
The new Roval Alpinist CLX III climbing wheels, which are the lightest ever from Specialized's component brand, weigh a claimed 1,131g – 134g lighter than their predecessors. They use the same hooked rim with its 33mm depth and 21mm internal rim width as before, but are now built with composite spokes from ARRIS which save over 103.5g compared with the steel DT Swiss Aerolites. The hubs use DT Swiss’s top 180 ratchet ring internals. The top S-Works Aethos 2 builds are specced with these wheels whereas the second-tier Specialized Aethos Pro bikes get the Alpinist CL IIs and the Aethos Expert builds get Roval Rapide C 38s.
As for prices, the S-Works builds with either SRAM Red AXS or Shimano Dura-Ace are £11,499, the Aethos Pro is £7,249 (both Force AXS and Ultegra Di2) and the Aethos Expert £5,499. The S-Works Aethos frameset is priced at £4999 and the Aethos frameset £3,499. These are slightly lower than the prices of the outgoing Aethos – the flagship S-Works model was £12,000 while the Pro came in at £8,000.
It looks like an intelligently targeted update that preserves the Aethos’s character, aesthetics and most importantly its low weight, while bringing the geometry, integration and tyre clearance into the mid 2020s. I just need to head over to Specialized HQ in Dorking to take the Aethos 2 for a spin in the Surrey Hills, so stay tuned for my first impressions and visit Specialized's website to find out all the details.
