2025 Specialized Tarmac SL8 Expert vs 2025 Specialized Aethos Pro
The 49 is the Specialized Aethos Pro size closest to your 44 Specialized Tarmac SL8 Expert. 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 Expert 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 Expert, 44Specialized Aethos Pro, 49Drawn to scale and lined up at the bottom bracket.
Geometry side by side
| Measurement | Specialized Tarmac SL8 Expert 44 | Specialized Aethos Pro 49 | Difference |
|---|---|---|---|
| Reach | 366 | 375mm | +9 mm |
| Stack | 501 | 514mm | +13 mm |
| Head tube angle | 70.5 | 71.75° | +1.3° |
| Seat tube angle | 75.5 | 75.5° | ±0.0° |
| Chainstay length | 410 | 410mm | ±0 mm |
| Wheelbase | 970 | 973mm | +3 mm |
| BB drop | 75 | 74mm | −1 mm |
| BB height | 266 | 266mm | ±0 mm |
| Standover | 723 | 705mm | −18 mm |
| Seat tube length | 433 | 431mm | −2 mm |
| Fork length | 370 | 369mm | −1 mm |
| Head tube length | 99 | 109mm | +10 mm |
| Effective top tube | not listed | 508mm |
Differences are the Specialized Aethos Pro minus the Specialized Tarmac SL8 Expert. Full charts: 2025 Specialized Tarmac SL8 Expert, 2025 Specialized Aethos Pro.
Where each sits in its class
Specialized Tarmac SL8 ExpertSpecialized Aethos Pro
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 Tarmac SL8 ExpertExpert | Specialized Aethos Pro |
|---|---|---|
| Frame | Specialized Tarmac SL8 FACT | not listed |
| Fork | Specialized FACT 10r Carbon | not listed |
| Shifter | Shimano Ultegra R8170 Di2 | not listed |
| Derailleur | Shimano Ultegra R8150 Di2, Shimano Ultegra R8150 Di2 front | not listed |
| Cassette | Shimano Ultegra | not listed |
| Chain | Shimano Ultegra | not listed |
| Crankset | Shimano Ultegra R8100 | not listed |
| Chainring | Shimano Ultegra | not listed |
| Bottom bracket | Shimano Ultegra | not listed |
| Wheelset | Roval C38 | not listed |
| Tire | Specialized S-Works Turbo | not listed |
| Brake | Shimano Ultegra R8170 Di2, Shimano Ultegra R8170 Di2 rear | not listed |
| Rotor | Shimano Ultegra | not listed |
| Handlebar | Specialized Expert Shallow Drop | not listed |
| Stem | Specialized Tarmac | not listed |
| Bar tape | Supacaz Super Sticky Kush | not listed |
| Headset | Integrated | not listed |
| Seatpost | Specialized S-Works Tarmac SL8 | not listed |
| Saddle | Specialized Power Expert | not listed |
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