Cannondale Synapse vs Specialized Roubaix vs Trek Domane Comparison: Detailed Comparison of the Best Endurance Bikes (2025)
Cannondale Synapse vs Specialized Roubaix vs Trek Domane: A Detailed Comparison of the Best Endurance Bikes (2025)
For a long time, road bikes were divided into two categories: road bikes and endurance bikes. While road bikes were designed to go fast, endurance bikes were designed to go long distances.
There has long been a debate about the endurance bike being an endangered species, squeezed between more comfortable road bikes with ever-increasing tire clearance that aren’t as fatiguing as they once were and all-road bikes that allow you to explore the dirt without committing to a true gravel bike.
However, the endurance bike is still not to be underestimated. Manufacturers are further increasing tire clearance and integrating features to smooth out the ride and add convenience, such as in-frame storage and additional mounting points. Mudguard mounts are almost always present.
Three of the best endurance bikes currently available are the Cannondale Synapse, the Specialized Roubaix SL8, and the Trek Domane, although Trek now bills the Domane as an all-road bike. Each approaches the mission of making longer rides more comfortable in different ways. Let’s see how these three contenders stack up.
Comfort Features: An In-Depth Review
The award for the most additional comfort features goes to Specialized. The Roubaix features the brand’s Future Shock 3 in the head tube, which offers up to 20mm of linear travel at the handlebars.
On the higher-end models, the Future Shock 3.3 is both on-the-go adjustable via a dial on the head tube cap and hydraulically damped. Mid-range bikes have the Future Shock 3.2, which is damped but not on-the-go adjustable, while lower-end Roubaix bikes have the Future Shock 3.1, which is undamped. All variants allow you to swap out three different spring rates and add or remove preload shims for precise ride tuning.
In the rear, the Roubaix’s flared seat tube, combined with a lower seatpost clamp, provides more compliance for more saddle comfort.
The Domane provides saddle compliance via Trek’s proven IsoSpeed technology, which decouples the seat tube from the top tube and seatstays. IsoSpeed is no longer adjustable on the latest Gen 4 Domane, and Trek bikes no longer include Front IsoSpeed, so front-end compliance depends on handlebar design and wide tires.
Cannondale doesn’t include any specific comfort features on its Synapse, relying instead on flex zones in the frame, a flexible seatpost, and, on higher-end bikes, a carbon bar/stem. It says its approach avoids adding extra weight.
The 2025 Cannondale Synapse has a one-piece stem/bar setup on the higher-end models, while the higher-end Roubaix and Domane have a two-piece design with carbon bars. On the lower-end models, alloy bars replace the carbon bars.
Tire Clearance: Ever Wider
Tire clearance continues to grow across all bike categories. It’s especially important for endurance bikes, as wider tires are a key part of the comfort equation.
Cannondale’s latest Synapse Carbon increases tire clearance to 42mm, though it remains at 32mm for the alloy Synapse. Cannondale runs 32mm tires across its entire carbon lineup.
The Roubaix can run 40mm tires, though Specialized also doesn’t take full advantage of the available clearance, running 32mm tires. The same goes for Trek, which runs 32mm tires despite running 38mm clearance.
The narrower tires allow for fenders on all three bikes, but it’s a little surprising that none of the brands choose to increase the suppleness of their frames with tires that would accentuate this feature, by running tires of a width that would now be considered normal on a road bike. Even Tadej Pogačar now runs 32mm tires in some races.
On the other hand, the tires fitted are likely to be a couple of millimeters wider than the stated width on the wider rims now typical for road bike wheels, so the actual width is probably closer to the stated clearance.
Additional Features: Long-Distance Convenience
Endurance bikes are increasingly gaining accessories to make them more useful for long rides.
In the case of the Synapse Carbon, there’s the option of integrated SmartSense lighting and rearview radar, powered by a central battery. It’s now better integrated, with the battery housed in the down tube, where there’s also room to store tools. The front light is brighter and smaller than the previous-generation bike, and also better integrated, with shorter exposed cables.
Having the lights already mounted on the bike eliminates the need to hunt for and install them yourself. On the other hand, the system adds weight that some riders might prefer to avoid. At launch, no Synapse Carbon spec came with SmartSense, except the top-end Lab71, so it’s easy to avoid it if you want.
Cannondale also adds its own front-wheel sensor to its bikes, providing speed and distance measurements independent of a cycle computer and, via the Cannondale app, alerts you to service intervals. It also turns the SmartSense system on when you start pedaling.
All Cannondale Synapse models include top-tube mounts for a bag.
The carbon Trek Domane also includes an internal storage compartment in the down tube, which allows you to keep repair tools with you without having to carry them in a pocket or a saddle bag. Frame storage is an increasingly popular feature on endurance, all-road, and gravel bikes, but Specialized doesn’t yet offer it on its endurance bikes, although it is a feature on the Diverge gravel bike.
In fact, Specialized doesn’t offer any additional value-added features on its Roubaix framesets. All three bikes do offer mounts for fenders and racks, though.
Frame Materials: Carbon vs. Aluminum
The Cannondale Synapse is offered in both carbon and aluminum. For the first time with the sixth-generation 2025 Synapse, there’s also a top-end Synapse Lab71 bike, with a sub-kilogram frame that’s said to be 150g lighter than the standard carbon frame. Meanwhile, Specialized only sells the Roubaix SL8 in carbon. It does offer two levels of carbon, however: FACT 12r and FACT 10r. The former uses higher-grade carbon for a lighter frame and is only found on the S-Works model.
Trek also offers two levels of carbon fiber, 800 Series OCLV on its SLR bikes and 500 Series on its SL bikes. There’s also an alloy Domane frame used on the lower-end bikes, all of which come with a carbon fork.
Weight: Lightness is the Goal
Cannondale hasn’t provided weights for its bikes, but we’d expect the non-SmartSense bikes to be competitive. The previous-generation SmartSense contributed around 500g to the bike’s weight, though, so even with the top-end Lab71 frame, we’d expect the flagship bike to be heavier than the competition at its price.
On the other hand, if you usually ride with lights, you’ll be adding most of the system’s 500g to a lighter bike, without the benefit of an integrated system.
At 7.2kg, the S-Works Roubaix SL8 is incredibly low weight for an endurance bike, although that comes at a high cost. The lower-level Roubaix SL8 Pro has a claimed weight of 8.1kg.
Trek claims a weight of 7.25kg for its top-spec Domane SLR 9, but again that’s a premium spec with a price tag to match. Moving down the range, the £8,450 Domane SLR 7 AXS’s claimed weight of 8.3kg is comparable to the Roubaix.
So, if you’re looking at a top-end bike, Specialized and Trek offer the lowest weights. Further down the ranges, bike weights are similar at similar prices.
Aerodynamics: An Increasingly Important Factor
Aerodynamics continues to dominate the road bike conversation, and all three bikes feature truncated airfoil tube sections that are said to make them faster. As you’d expect from endurance bikes, they’re less pronounced than those on Trek and Specialized’s aero road bikes, while Cannondale says they use similar shapes to the SuperSix Evo.
Both the carbon Domane and Synapse Carbon feature hidden cable routing, a design feature that’s said to improve the bikes’ aerodynamics. In the case of the Roubaix, the Future Shock headset precludes internal cable routing through the head tube. The Synapse’s SmartSense front light is unlikely to be aero, although there’s a similar penalty for attaching lights to the Roubaix or Domane.
All three bikes have classic endurance bike geometry, with a higher stack and shorter reach for a more upright riding position. They also all have a longer wheelbase and longer chainstays for a more stable ride.
The Roubaix is somewhat of an exception in having a significantly higher stack than the Synapse and Domane. The head tube angle is also steeper; a slacker head tube angle tends to favor a more stable ride. The length The Roubaix’s shorter head tube accommodates the Future Shock suspension fork, and its shorter seat tube allows for seatpost compliance.
Sizes: Wide Choice for Every Rider
Cannondale offers the latest Synapse Carbon in a wide range of sizes: 44, 48, 51, 54, 56, 58, and 61. The alloy Synapse offers the same range of size options, which Cannondale says will fit a wide range of rider heights, from 152cm to 203cm.
Specialized sells the Roubaix in sizes 44, 49, 52, 54, 56, 58, and 61, saying these will fit riders from 142cm to 205cm tall.
The Domane SLR is sold in sizes 47, 50, 52, 54, 56, 58, 60, and 62. Trek says it should fit riders between 5’10” and 6’7” (152cm and 195cm). The Domane SL adds a 44 and is said to fit riders 5’10” and above, while the Domane AL sizing is slightly different, offering sizes 44, 49, 52, 54, 56, 58, and 61 with listed rider heights between 5’10” and 6’3” (191cm).
Groupsets: A Wide Variety of Components
Most Synapse builds include Shimano double-chainring groupsets. The exception is the top-end Lab71 bike, which is equipped with a single-chainring SRAM Red XPLR AXS groupset. Nearly the entire Shimano range is represented, from the 12-speed Ultegra to the 9-speed Sora, all with 50/34t cranksets and 11-34t or 11-36t cassettes. None, with the exception of the Lab71 bike, include a power meter.
Specialized is much more SRAM-oriented, offering SRAM Red AXS with a power meter, 46/33t crankset and 10-36t cassette, as well as a 50/34t, 11-34t Dura-Ace spec with a 4iiii power meter as an option on its top-end S-Works Roubaix. Further down the range are the Force, Rival and Apex builds, with power meters on all but the Apex. Its Shimano options include 105 with 50/34t, 11-36t gearing and Tiagra with 50/34t, 11-34t.
The Trek Domane also stands out with a SRAM Red AXS build with a power meter. There’s also a Dura-Ace spec offered at the top end, while further down the range there are Shimano and SRAM builds, with most SRAM builds including a power meter. The cheapest Domanes come with an 8-speed Shimano Claris.
Cannondale Synapse Range: Models
The Cannondale Synapse range includes carbon and alloy framed bikes and covers a wide price range, with the top-end Lab71 costing ten times the price of the entry-level alloy Synapse 3.
Specialized Roubaix SL8 Range: Models
Both Cannondale and Trek produce their endurance bikes in both alloy and carbon fibre. In contrast, Specialized only sells the Roubaix in a carbon frame. Its alloy-framed bike with endurance geometry is the Allez, which comes in two specs; there’s also the Allez Sprint, which has a more aggressive racing geometry.
Trek Domane Lineup: Models
With both carbon and alloy options, the Domane offers plenty of choice: there are six SLR-level and four SL-level carbon bikes, plus another four alloys available. There’s even an entry-level rim-brake model still in the lineup.
Cannondale Synapse vs. Specialized Roubaix vs. Trek Domane: Which Should You Choose?
Choosing between the Cannondale Synapse, Specialized Roubaix, and Trek Domane isn’t easy. All three bike lines receive praise for their ride comfort, making them some of the best choices for endurance bikes.
The Roubaix was the original endurance bike, and Specialized’s updates over the years have kept it at the forefront of the category. The bike’s combination of front and rear micro-suspension provides excellent comfort, and the ability to run 40mm tires now begins to overlap with the all-road category, providing the prowess to handle less extreme off-road conditions when equipped with the right tires.
The Trek Domane also has the ability to take you to lighter gravel terrain, as well as providing excellent road compliance on pavement. The Domane’s in-frame storage is unique among the three bikes. It’s handy to know you’ve got the tools to do a lot of road repairs, and it frees up your jersey pockets for more food, a jacket, or just a more comfortable ride.
The Synapse goes further than the other two bikes to prepare you for longer rides. It’s comfortable without incorporating the extra complications that can be difficult and expensive to keep in tune over time. SmartSense may dampen the proposition for some riders, but that’s limited to the very highest-end bike. There’s the most tire clearance of the three for carbon bikes, which also include in-frame storage.
If you look further down the bike ranges, only Trek and Cannondale offer really affordable options with their alloy frame bikes.
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