Specialized Roubaix vs Specialized Aethos
Choosing between the Specialized Roubaix and the Specialized Aethos? This compares the 2026 Specialized Roubaix SL8 Comp with the 2025 Specialized Aethos, size by size, from the geometry Specialized publishes. Pick any size to compare it in the full tool.
The 58 is the Specialized Aethos size closest to your 54 Specialized Roubaix SL8 Comp. We match frame stack and reach. This is a geometry comparison, not a fit recommendation; stem, spacers, handlebars and saddle setup also affect your riding position.
What changes on the Specialized Aethos
Compared with the Specialized Roubaix SL8 Comp in 54, the Specialized Aethos in 58 places the top of the head tube 6 mm higher and 21 mm further forward, relative to the bottom bracket.
- Frame stack
- +6 mm
- Higher front end
- Frame reach
- +21 mm
- Longer frame reach
- Wheelbase
- ±0 mm
- About the same
- Head angle
- +1.2°
- Steeper: sharper steering
- Chainstays
- −10 mm
- Shorter: livelier
Which Specialized Aethos size matches your Specialized Roubaix SL8 Comp
For each Specialized Roubaix SL8 Comp size, the Specialized Aethos size with the closest frame stack and reach. Stack and reach show how far off it is: the Specialized Aethos minus the Specialized Roubaix SL8 Comp. A geometry match, not a fit recommendation.
| Specialized Roubaix SL8 Comp size | Closest size | Stack | Reach |
|---|---|---|---|
| 44 | 54 | +1 mm | +31 mm |
| 49 | 54 | −5 mm | +21 mm |
| 52 | 56 | −1 mm | +25 mm |
| 54 | 58 | +6 mm | +21 mm |
| 56 | 58 | −14 mm | +13 mm |
| 58 | 61 | −18 mm | +11 mm |
| 61 | 61 | −53 mm | +5 mm |
| 64 | 61 | −73 mm | −1 mm |
The two frames
Specialized Roubaix SL8 Comp, 54Specialized Aethos, 58Drawn to scale and lined up at the bottom bracket.
Geometry side by side
| Measurement | Specialized Roubaix SL8 Comp 54 | Specialized Aethos 58 | Difference |
|---|---|---|---|
| Reach | 381 | 402mm | +21 mm |
| Stack | 585 | 591mm | +6 mm |
| Head tube angle | 72.3 | 73.5° | +1.2° |
| Seat tube angle | 74 | 73.5° | −0.5° |
| Effective top tube | 550 | 577mm | +27 mm |
| Chainstay length | 420 | 410mm | −10 mm |
| Wheelbase | 1005 | 1005mm | ±0 mm |
| BB drop | 78 | 72mm | −6 mm |
| BB height | 270 | 268mm | −2 mm |
| Standover | 766 | 796mm | +30 mm |
| Seat tube length | 465 | 532mm | +67 mm |
| Fork length | 375 | 369mm | −6 mm |
| Head tube length | 122 | 184mm | +62 mm |
Differences are the Specialized Aethos minus the Specialized Roubaix SL8 Comp. Full charts: 2026 Specialized Roubaix SL8 Comp, 2025 Specialized Aethos.
Where each sits in its class
Specialized Roubaix SL8 CompSpecialized Aethos
Each bike is ranked against the other road bikes on Quiver, on frame geometry alone. Not your hand position or ride feel.
What each ships with
The stock build of each bike's first listed trim. Parts that match are dimmed.
| Part | Specialized Roubaix SL8 CompSL8 Comp | Specialized Aethos |
|---|---|---|
| Frame | Specialized FACT 10r | not listed |
| Fork | Specialized Future Shock 3.2 | not listed |
| Shifter | Shimano 105 R7170 Di2 | not listed |
| Derailleur | Shimano 105 R7150 Di2, Shimano 105 Di2 | not listed |
| Cassette | Shimano 105 R7100 | not listed |
| Chain | Shimano SLX M7100 | not listed |
| Crankset | Shimano 105 | not listed |
| Chainring | Shimano 105 | not listed |
| Bottom bracket | Shimano Threaded BSA | not listed |
| Wheelset | DT Swiss G540 | not listed |
| Tire | Specialized Mondo, Mondo Endurance | not listed |
| Rim | DT Swiss G 540 | not listed |
| Brake | Shimano 105 | not listed |
| Handlebar | Specialized Hover | not listed |
| Stem | Specialized Future | not listed |
| Grips | Supacaz Super Sticky Kush | not listed |
| Bar tape | Supacaz Super Sticky Kush | not listed |
| Seatpost | Specialized S-Works Pave | not listed |
| Saddle | Specialized Power Sport | not listed |