2025 Specialized Tarmac SL8 Pro Shimano vs 2025 Specialized Aethos Pro
The 58 is the Specialized Aethos Pro size closest to your 58 Specialized Tarmac SL8 Pro Shimano. 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 Pro Shimano in 58, the Specialized Aethos Pro in 58 places the top of the head tube at about the same height and about as far forward, relative to the bottom bracket.
- Frame stack
- ±0 mm
- About the same height
- Frame reach
- ±0 mm
- About the same reach
- Wheelbase
- −1 mm
- About the same
- Head angle
- ±0.0°
- About the same head angle
- Chainstays
- ±0 mm
- About the same
The two frames
Specialized Tarmac SL8 Pro Shimano, 58Specialized Aethos Pro, 58Drawn to scale and lined up at the bottom bracket.
Geometry side by side
| Measurement | Specialized Tarmac SL8 Pro Shimano 58 | Specialized Aethos Pro 58 | Difference |
|---|---|---|---|
| Reach | 402mm | 402mm | ±0 mm |
| Stack | 591mm | 591mm | ±0 mm |
| Head tube angle | 73.5° | 73.5° | ±0.0° |
| Seat tube angle | 73.5° | 73.5° | ±0.0° |
| Chainstay length | 410mm | 410mm | ±0 mm |
| Wheelbase | 1006mm | 1005mm | −1 mm |
| BB drop | 72mm | 72mm | ±0 mm |
| BB height | 268mm | 268mm | ±0 mm |
| Standover | 808mm | 796mm | −12 mm |
| Seat tube length | 515mm | 532mm | +17 mm |
| Fork length | 370mm | 369mm | −1 mm |
| Head tube length | 184mm | 184mm | ±0 mm |
| Effective top tube | not listed | 577mm |
Differences are the Specialized Aethos Pro minus the Specialized Tarmac SL8 Pro Shimano. Full charts: 2025 Specialized Tarmac SL8 Pro Shimano, 2025 Specialized Aethos Pro.
Where each sits in its class
Specialized Tarmac SL8 Pro ShimanoSpecialized 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 Pro ShimanoPro - Shimano Ultegra Di2 | Specialized Aethos Pro |
|---|---|---|
| Frame | Specialized Tarmac SL8 FACT | not listed |
| Shifter | Shimano Ultegra R8170 Di2 | not listed |
| Derailleur | Shimano Ultegra R8150 Di2 | not listed |
| Cassette | Shimano Ultegra | not listed |
| Chain | Shimano Ultegra | not listed |
| Crankset | Shimano Ultegra R8100 | not listed |
| Wheelset | Roval Rapide CL II | not listed |
| Tire | Specialized S-Works Turbo | not listed |
| Brake | Shimano Ultegra R8170 Di2 | not listed |
| Handlebar | Roval Rapide Cockpit | not listed |
| Seatpost | Specialized S-Works Tarmac SL8 | not listed |
| Saddle | Specialized Power | not listed |
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