2025 Specialized Roubaix SL8 Pro vs 2027 Trek Domane AL 4 Gen 4
The 56 is the Trek Domane AL 4 Gen 4 size closest to your 54 Specialized Roubaix SL8 Pro. 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 Trek Domane AL 4 Gen 4
Compared with the Specialized Roubaix SL8 Pro in 54, the Trek Domane AL 4 Gen 4 in 56 places the top of the head tube 6 mm higher and 4 mm further back, relative to the bottom bracket. Its wheelbase is 13 mm longer, which can contribute to stability at speed.
- Frame stack
- +6 mm
- Higher front end
- Frame reach
- −4 mm
- Shorter frame reach
- Wheelbase
- +13 mm
- Longer: steadier at speed
- Head angle
- −0.4°
- Slacker: calmer steering
- Chainstays
- ±0 mm
- About the same
The two frames
Specialized Roubaix SL8 Pro, 54Trek Domane AL 4 Gen 4, 56Drawn to scale and lined up at the bottom bracket.
Geometry side by side
| Measurement | Specialized Roubaix SL8 Pro 54 | Trek Domane AL 4 Gen 4 56 | Difference |
|---|---|---|---|
| Reach | 381mm | 377 | −4 mm |
| Stack | 585mm | 591 | +6 mm |
| Head tube angle | 72.3° | 71.9 | −0.4° |
| Seat tube angle | 74° | 73.3 | −0.7° |
| Chainstay length | 420mm | 420 | ±0 mm |
| Wheelbase | 1005mm | 1018 | +13 mm |
| BB drop | 78mm | 78 | ±0 mm |
| BB height | 270mm | not listed | |
| Standover | 766mm | 776 | +10 mm |
| Seat tube length | 465mm | 525 | +60 mm |
| Fork length | 375mm | not listed | |
| Head tube length | 122mm | 175 | +53 mm |
| Effective top tube | not listed | 554 |
Differences are the Trek Domane AL 4 Gen 4 minus the Specialized Roubaix SL8 Pro. Full charts: 2025 Specialized Roubaix SL8 Pro, 2027 Trek Domane AL 4 Gen 4.
Where each sits in its class
Specialized Roubaix SL8 ProTrek Domane AL 4 Gen 4
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 Roubaix SL8 ProSL8 Pro | Trek Domane AL 4 Gen 4Gen 4 |
|---|---|---|
| Fork | Specialized Future Shock 3.3 | Trek Domane AL |
| Shifter | Shimano Ultegra R8170 Di2 | Shimano Tiagra R4020 |
| Derailleur | Shimano Ultegra R8150 Di2 | Shimano Tiagra R4000, Shimano Tiagra 4700 |
| Cassette | Shimano Ultegra | Shimano RS400 |
| Chain | Shimano XT M8100 | Shimano LG500 |
| Crankset | Shimano Ultegra R8100 | Shimano Tiagra R4000 |
| Wheelset | Roval Terra CL II | Bontrager Paradigm 23 |
| Tire | Specialized S-Works Mondo 2BR | Bontrager Kwaremont |
| Brake | Shimano Ultegra | not listed |
| Stem | Specialized Future | Bontrager Elite |
| Seatpost | Specialized S-Works Pave Seat post | Bontrager Comp |
| Saddle | Specialized Power Pro Mirror | Trek Verse Short |
| Frame | not listed | Trek Domane AL |
| Chainring | not listed | Shimano Tiagra 4700 |
| Bottom bracket | not listed | Shimano RS501 |
| Hub | not listed | Formula RX-142, Formula RX-512 |
| Rim | not listed | Bontrager Paradigm 23 |
| Rotor | not listed | Shimano SM-RT66 |
| Handlebar | not listed | Bontrager Comp |
| Bar tape | not listed | Bontrager Supertack Perf |
| Headset | not listed | Bontrager Expander Plug |
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