2026 Trek Domane SL Gen 4 vs 2025 Specialized Roubaix SL8 Pro
The 56 is the Specialized Roubaix SL8 Pro size closest to your 58 Trek Domane SL Gen 4. 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 Roubaix SL8 Pro
Compared with the Trek Domane SL Gen 4 in 58, the Specialized Roubaix SL8 Pro in 56 places the top of the head tube 6 mm lower and 9 mm further forward, relative to the bottom bracket. Its wheelbase is 10 mm shorter, which can contribute to quicker direction changes.
- Frame stack
- −6 mm
- Lower front end
- Frame reach
- +9 mm
- Longer frame reach
- Wheelbase
- −10 mm
- Shorter: quicker to change direction
- Head angle
- +1.0°
- Steeper: sharper steering
- Chainstays
- −5 mm
- Shorter: livelier
The two frames
Trek Domane SL Gen 4, 58Specialized Roubaix SL8 Pro, 56Drawn to scale and lined up at the bottom bracket.
Geometry side by side
| Measurement | Trek Domane SL Gen 4 58 | Specialized Roubaix SL8 Pro 56 | Difference |
|---|---|---|---|
| Reach | 380 | 389mm | +9 mm |
| Stack | 611 | 605mm | −6 mm |
| Head tube angle | 72.0 | 73° | +1.0° |
| Seat tube angle | 73.0 | 73.5° | +0.5° |
| Effective top tube | 567 | not listed | |
| Chainstay length | 425 | 420mm | −5 mm |
| Wheelbase | 1022 | 1012mm | −10 mm |
| BB drop | 78 | 78mm | ±0 mm |
| BB height | 258 | 270mm | +12 mm |
| Standover | 796 | 787mm | −9 mm |
| Seat tube length | 548 | 485mm | −63 mm |
| Head tube length | 195 | 140mm | −55 mm |
| Fork length | not listed | 375mm |
Differences are the Specialized Roubaix SL8 Pro minus the Trek Domane SL Gen 4. Full charts: 2026 Trek Domane SL Gen 4, 2025 Specialized Roubaix SL8 Pro.
Where each sits in its class
Trek Domane SL Gen 4Specialized Roubaix SL8 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 | Trek Domane SL Gen 4 | Specialized Roubaix SL8 ProSL8 Pro |
|---|---|---|
| Fork | not listed | Specialized Future Shock 3.3 |
| Shifter | not listed | Shimano Ultegra R8170 Di2 |
| Derailleur | not listed | Shimano Ultegra R8150 Di2 |
| Cassette | not listed | Shimano Ultegra |
| Chain | not listed | Shimano XT M8100 |
| Crankset | not listed | Shimano Ultegra R8100 |
| Wheelset | not listed | Roval Terra CL II |
| Tire | not listed | Specialized S-Works Mondo 2BR |
| Brake | not listed | Shimano Ultegra |
| Stem | not listed | Specialized Future |
| Seatpost | not listed | Specialized S-Works Pave Seat post |
| Saddle | not listed | Specialized Power Pro Mirror |
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