2026 Specialized Tarmac SL8 Comp Shimano vs 2025 Specialized Aethos Pro
The 54 is the Specialized Aethos Pro size closest to your 54 Specialized Tarmac SL8 Comp 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 Comp Shimano in 54, the Specialized Aethos Pro in 54 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
- ±0 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 Comp Shimano, 54Specialized Aethos Pro, 54Drawn to scale and lined up at the bottom bracket.
Geometry side by side
| Measurement | Specialized Tarmac SL8 Comp Shimano 54 | Specialized Aethos Pro 54 | Difference |
|---|---|---|---|
| Reach | 384mm | 384mm | ±0 mm |
| Stack | 544mm | 544mm | ±0 mm |
| Head tube angle | 73° | 73° | ±0.0° |
| Seat tube angle | 74° | 74° | ±0.0° |
| Effective top tube | 541mm | 540mm | −1 mm |
| Chainstay length | 410mm | 410mm | ±0 mm |
| Wheelbase | 978mm | 978mm | ±0 mm |
| BB drop | 72mm | 72mm | ±0 mm |
| BB height | 268mm | 268mm | ±0 mm |
| Standover | 768mm | 748mm | −20 mm |
| Seat tube length | 473mm | 481mm | +8 mm |
| Fork length | 370mm | 369mm | −1 mm |
| Head tube length | 137mm | 137mm | ±0 mm |
Differences are the Specialized Aethos Pro minus the Specialized Tarmac SL8 Comp Shimano. Full charts: 2026 Specialized Tarmac SL8 Comp Shimano, 2025 Specialized Aethos Pro.
Where each sits in its class
Specialized Tarmac SL8 Comp 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 Comp ShimanoComp - Shimano 105 Di2 | Specialized Aethos Pro |
|---|---|---|
| Frame | Specialized Tarmac SL8 FACT | not listed |
| Shifter | Shimano 105 R7170 Di2 | not listed |
| Derailleur | Shimano 105 R7170 | not listed |
| Cassette | Shimano 105 R7100 | not listed |
| Chain | Shimano SLX M7100 | not listed |
| Crankset | Shimano 105 R7100 | not listed |
| Wheelset | DT Swiss R470 | not listed |
| Tire | Specialized S-Works Turbo | not listed |
| Brake | Shimano 105 | not listed |
| Headset | Specialized SL7 | not listed |
| Seatpost | Specialized S-Works Tarmac SL8 | not listed |
| Saddle | Specialized Power Sport | not listed |
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