Specialized has unveiled the new Aethos 2 – the lightest road bike it has ever produced, and sporting several new modern features that bring it up to date with 2025 road bike design trends.
This has meant a move to full internal routing via Roval’s latest Alpinist II cockpit and the same headset layout as seen on the Tarmac SL8.
While this might be to the chagrin of fans of the original bike, Specialized says this main change was made to meet the evolving demands of its customers.
Alongside this, the frame has seen an update to its geometry to make it more comfortable to ride, a move to SRAM’s UDH (Universal Derailleur Hanger) standard, and a rise to 35mm tyre clearance.
An S-Works Aethos frame is said to weigh 595g, yielding a 5.98kg total build weight for the range-topping SRAM Red AXS spec, which costs £11,499 / $13,999 / €13,499.
- Read our Specialized Aethos 2 first ride review
- Read about Roval’s latest Alpinist CLX III wheelset and Alpinist II cockpit
Goodbye external routing
The old Aethos featured a two-piece cockpit with cables routed externally. These entered at the top of the down tube and fork shoulder, but the Aethos 2 sees cables fully integrated via sibling brand Roval’s new Alpinist II one-piece cockpit launched 48 hours prior.
Specialized says the move reflects the growing demand for “aesthetically pleasing” integrated front ends (compared to externally routed bars and stems). The Alpinist II cockpit is available in 15 sizes for customers at point of purchase.
That said, those hoping to build up an Aethos 2 from scratch with an alternative handlebar and stem are still able to adopt a two-piece design via a special headset adaptor – they’ll just need to bear in mind that the brake hoses must enter through front-facing ports in the bearing, like a Tarmac SL8.
The move to internal routing has also seen the removal of the down tube port that would house gear cables for mechanical shifting – accordingly, the Aethos 2 frameset can now only sport electronic drivetrains.
Specialized says it has given the carbon layup an overhaul, strengthening the triangle joins, while aiming to improve compliance and ride smoothness.
The brand’s marketing machine calls the process ‘Flow State Design’, whereby it prioritises developing rounded tube shapes (which are claimed to bear stresses more efficiently) versus adding layers of carbon to improve stiffness.
At the rear, the dropouts now meet SRAM’s UDH standard. The move saw the dropout gain “significant” extra material, according to Specialized’s road and gravel category lead, Alex Jerome.
The head tube has also been made 15mm taller as part of a geometry rethink, adding further material to the frame.
To combat the weight gain, marginal savings are seen at the seat clamp (-9g), brake mounts (-2g) and bottom bracket cups (-6g), plus a custom derailleur hanger (-2g).
All in, the S-Works frame, formed using Specialized’s Fact 12r carbon, is said to weigh 595g in a size 56cm – only 10g more than the previous-generation bike. That’s 62g less than the claimed weight of Cervélo’s latest R5 and 0.7g less than the claim attached to the Black Series Corsa frame in a size medium (broadly equivalent to 54cm in Specialized’s parlance).
The ‘standard’ Fact 10r carbon frame, used for all bikes specced below the S-Works level, is claimed to weigh 705g.
Is the Aethos an endurance bike?
The new Aethos is not quite an endurance bike, although Specialized concedes it landed on the taller head tube to contribute to a more comfortable ride position for more riders.
The head tube has also been slackened by 0.5 degrees (on average through the size range), and the chainstays lengthened by 7mm. Specialized says this makes handling smoother and more stable overall.
Meanwhile, the bottom bracket drop has lowered by 3mm. In isolation, Specialized claims this makes cornering feel more “planted”, while compensating for the use of wider tyres relative to the previous Aethos.
Tweaks to the bottom bracket area, plus the extension of the chainstays, see tyre clearance climb to 35mm (measured, up from 32mm), with the ISO-mandated 4mm space around a tyre measuring that wide.
| Size (cm) | 49 | 52 | 54 | 56 | 58 | 61 |
|---|---|---|---|---|---|---|
| Seat tube (mm) | 450 | 470 | 490 | 510 | 535 | 570 |
| Seat angle (°) | 75.5 | 74.5 | 74 | 74 | 74 | 74 |
| Head tube (mm) | 114 | 128 | 150 | 169 | 198 | 218 |
| Head angle (°) | 71.4 | 72.1 | 72.5 | 73 | 73 | 73.5 |
| Top tube (mm) | 522 | 538 | 559 | 580 | 606 | 627 |
| Stack (mm) | 522 | 526 | 544 | 557 | 572 | 584 |
| Reach (mm) | 373 | 372 | 372 | 372 | 372 | 372 |
| BB drop (mm) | 72 | 72 | 72 | 72 | 72 | 72 |
| Wheelbase (mm) | 978 | 981 | 992 | 998 | 1013 | 1020 |
| Chainstay (mm) | 410 | 410 | 410 | 410 | 410 | 410 |
| Standover (mm) | 719 | 737 | 759 | 779 | 805 | 834 |
Roval Alpinist components
Specialized says the second-generation Aethos frame is designed to dovetail with its latest Roval Alpinist components.
The Alpinist II cockpit is the main change, of course, which Specialized says has been optimised to damp ride vibrations by 28.3% compared to the Rapide cockpit used for the Tarmac SL8.
The two are interchangeable, however, with the cockpits and frames using the same standards and internal-routing layout.
Specialized says customers of S-Works and Pro-level bikes have free choice of 15 Alpinist II cockpit sizes at point of purchase, which can be arranged via its dealers. Expert-spec buyers will have a size choice of the old cockpit. The same applies to the Alpinist seatpost, which can be had in a setback or inline format.
The seatpost has remained the same as previously, retaining the standard 27.2mm round shape, save for the modified seat clamp. Specialized says this new clamp will be available as an aftermarket upgrade.
Roval supplies its Alpinist CLX III wheelset with the two S-Works-spec bikes, which is also claimed to have been optimised to work with the Aethos 2 frameset.
Alpinist CL II wheelsets will be supplied with Pro-spec bikes, and the C38 with the Expert bikes, but it’s worth noting the rim beds have seen a “rolling change” to make them “fully compliant” with ETRTO/ISO standards, according to Roval product lead, Chris Whelan.
Specialized Aethos 2 pricing, specs and claimed weights
The Specialized Aethos 2 range includes two S-Works level bikes, weighing 5.98kg (in a size 56cm) with a SRAM Red AXS groupset, and 6.05kg for a Shimano Dura-Ace Di2 R9200 version. These cost £11,499 / $13,999 / €13,499.
There are four ‘standard’ bikes, with prices starting from £5,499 / $6,999 / €6,299. Unlike the previous Aethos, there is no 105 Di2 R7100 or Rival AXS built bike, or (of course) mechanical builds.
Specialized S-Works Aethos 2 AXS
- Price: £11,499 / $13,999 / €13,499
- Groupset: SRAM Red AXS
- Power meter: Yes, Red AXS (dual-sided)
- Wheelset: Roval Alpinist CLX III
- Tyres: S-Works Turbo TLR, 700x28c
- Claimed weight: 5.98kg
Specialized S-Works Aethos 2 Di2
- Price: £11,499 / $13,999 / €13,499
- Groupset: Shimano Dura-Ace Di2 R9200
- Power meter: Yes, 4iiii Precision Pro (dual-sided)
- Wheelset: Roval Alpinist CLX III
- Tyres: S-Works Turbo TLR, 700x28c
- Claimed weight: 6.05kg
Specialized Aethos 2 Pro AXS
- Price: £7,249 / $8,499 / €8,499
- Groupset: SRAM Force AXS
- Power meter: Yes, SRAM Force AXS
- Wheelset: Roval Alpinist CL II
- Tyres: S-Works Turbo TLR, 700x28c
- Claimed weight: 6.71kg
Specialized Aethos 2 Pro Di2
- Price: £7,249 / $8,499 / €8,499
- Groupset: Shimano Ultegra Di2 R8100
- Power meter: Yes, 4iiii Precision Pro
- Wheelset: Roval Alpinist CL II
- Tyres: S-Works Turbo TLR, 700x28c
- Claimed weight: 6.73kg
Specialized Aethos 2 Expert AXS
- Price: £5,499 / $6,999 / €6,299
- Groupset: SRAM Force AXS
- Power meter: No
- Wheelset: Roval C38
- Tyres: S-Works Turbo, 700x28c
- Claimed weight: 7.05kg
Specialized Aethos 2 Expert Di2
- Price: £5,499 / $6,999 / €6,299
- Groupset: Shimano Ultegra Di2 R8100
- Power meter: No
- Wheelset: Roval C38
- Tyres: S-Works Turbo, 700x28c
- Claimed weight: 7.12kg
