2026 Specialized Tarmac SL8 vs 2025 Specialized Aethos Pro
The 49 is the Specialized Aethos Pro size closest to your 44 Specialized Tarmac SL8. 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 Pro
Compared with the Specialized Tarmac SL8 in 44, the Specialized Aethos Pro in 49 places the top of the head tube 13 mm higher and 9 mm further forward, relative to the bottom bracket. Its wheelbase is 3 mm longer, which can contribute to stability at speed.
- Frame stack
- +13 mm
- Higher front end
- Frame reach
- +9 mm
- Longer frame reach
- Wheelbase
- +3 mm
- Longer: steadier at speed
- Head angle
- +1.3°
- Steeper: sharper steering
- Chainstays
- ±0 mm
- About the same
The two frames
Specialized Tarmac SL8, 44Specialized Aethos Pro, 49Drawn to scale and lined up at the bottom bracket.
Geometry side by side
| Measurement | Specialized Tarmac SL8 44 | Specialized Aethos Pro 49 | Difference |
|---|---|---|---|
| Reach | 366mm | 375mm | +9 mm |
| Stack | 501mm | 514mm | +13 mm |
| Head tube angle | 70.5° | 71.75° | +1.3° |
| Seat tube angle | 75.5° | 75.5° | ±0.0° |
| Effective top tube | 496mm | 508mm | +12 mm |
| Chainstay length | 410mm | 410mm | ±0 mm |
| Wheelbase | 970mm | 973mm | +3 mm |
| BB drop | 74mm | 74mm | ±0 mm |
| BB height | 266mm | 266mm | ±0 mm |
| Standover | 723mm | 705mm | −18 mm |
| Seat tube length | 433mm | 431mm | −2 mm |
| Fork length | 370mm | 369mm | −1 mm |
| Head tube length | 99mm | 109mm | +10 mm |
Differences are the Specialized Aethos Pro minus the Specialized Tarmac SL8. Full charts: 2026 Specialized Tarmac SL8, 2025 Specialized Aethos Pro.
Where each sits in its class
Specialized Tarmac SL8Specialized Aethos Pro
Each bike is ranked against the other road bikes on Quiver, on frame geometry alone. Not your hand position or ride feel.
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