2025 Specialized Aethos FACT 12r Carbon vs 2026 Specialized Tarmac SL8 Pro Shimano
The Specialized Tarmac SL8 Pro Shimano size closest to your 54 is the 54. Compare the 54 instead
What changes on the Specialized Tarmac SL8 Pro Shimano
Compared with the Specialized Aethos FACT 12r Carbon in 54, the Specialized Tarmac SL8 Pro Shimano in 52 places the top of the head tube 17 mm lower and 4 mm further back, relative to the bottom bracket. Its wheelbase is 3 mm shorter, which can contribute to quicker direction changes.
- Frame stack
- −17 mm
- Lower front end
- Frame reach
- −4 mm
- Shorter frame reach
- Wheelbase
- −3 mm
- Shorter: quicker to change direction
- Head angle
- −0.5°
- Slacker: calmer steering
- Chainstays
- ±0 mm
- About the same
The two frames
Specialized Aethos FACT 12r Carbon, 54Specialized Tarmac SL8 Pro Shimano, 52Drawn to scale and lined up at the bottom bracket.
Geometry side by side
| Measurement | Specialized Aethos FACT 12r Carbon 54 | Specialized Tarmac SL8 Pro Shimano 52 | Difference |
|---|---|---|---|
| Reach | 384mm | 380 | −4 mm |
| Stack | 544mm | 527 | −17 mm |
| Head tube angle | 73° | 72.5 | −0.5° |
| Seat tube angle | 74° | 74 | ±0.0° |
| Effective top tube | 540mm | not listed | |
| Chainstay length | 410mm | 410 | ±0 mm |
| Wheelbase | 978mm | 975 | −3 mm |
| BB drop | 72mm | not listed | |
| BB height | 268mm | not listed | |
| Standover | 748mm | not listed | |
| Seat tube length | 481mm | not listed | |
| Fork length | 369mm | not listed | |
| Head tube length | 137mm | 120 | −17 mm |
Differences are the Specialized Tarmac SL8 Pro Shimano minus the Specialized Aethos FACT 12r Carbon. Full charts: 2025 Specialized Aethos FACT 12r Carbon, 2026 Specialized Tarmac SL8 Pro Shimano.
Where each sits in its class
Specialized Aethos FACT 12r CarbonSpecialized Tarmac SL8 Pro Shimano
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 Aethos FACT 12r CarbonS-Works FACT 12r Carbon | Specialized Tarmac SL8 Pro ShimanoPro - Shimano Ultegra Di2 |
|---|---|---|
| Frame | Specialized S-Works Aethos FACT | Specialized Tarmac SL8 |
| Seatpost | Roval Alpinist | Specialized S-Works Tarmac SL8 |
| Fork | not listed | Specialized FACT 10r |
| Shifter | not listed | Shimano Ultegra R8170 |
| Derailleur | not listed | Shimano Ultegra R8150 Di2 |
| Cassette | not listed | Shimano Ultegra |
| Chain | not listed | Shimano XT M8100 |
| Crankset | not listed | Shimano Ultegra R81000 |
| Bottom bracket | not listed | Shimano Threaded BSA |
| Wheelset | not listed | Roval Rapide CL III |
| Tire | not listed | Specialized S-Works Turbo |
| Brake | not listed | Shimano Ultegra R8170 |
| Rotor | not listed | Shimano Ultegra R8170 |
| Handlebar | not listed | Roval Rapide Cockpit |
| Stem | not listed | Roval Rapide Cockpit |
| Bar tape | not listed | Supacaz Super Sticky Kush |
| Saddle | not listed | Specialized Power Pro |
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