Specialized S-Works Tarmac SL8 review in our 2025 road bike comparison test

Specialized S-Works Tarmac SL8 in review – The perfect blend of lightweight design and aero efficiency? With the coveted S-Works variant, Specialized raised the bar yet again. But how did the iconic road bike fare against the competition in our race bike comparison test? And is its reputation as the ultimate all-rounder enough to secure it a top spot? Let’s find out whether the Tarmac SL8 truly lives up to the hype.

With the Specialized S-Works Tarmac SL8 in review, Specialized enter the race with a true road bike icon. In the road bike community, Specialized’s versatile all-rounder is considered the ultimate bike. If you take a closer look at the latest Tarmac SL8 model, this comes as no surprise: it’s incredibly lightweight and yet aerodynamic enough to give even dedicated aero bikes a run for their money – or at least, that’s what Specialized’s marketing department claims. And not without reason: at 6.89 kg, our test bike is right at the UCI weight limit, and yet still rolls deep-section aero wheels. This combination already impressed us in our Mont Ventoux climbing comparison test, where the Tarmac truly excelled. But how does it hold up in direct comparison with the racing competition?

Specialized S-Works Tarmac SL8 – One bike for everything or everything for one bike?

The Tarmac was designed to strike the perfect balance between lightweight design and aerodynamics. But how did Specialized’s engineers achieve this? In a nutshell, they merged the Venge’s aerodynamic front and with the lightweight rear end of the Aethos, all while preserving the core Tarmac DNA– in other words, a fine blend of pure road racing expertise in one bike. Specialized had already retired the aero-focused Venge with the release of the SL7, signalling a future built around a “One Bike to Rule Them All” concept, which is designed for all conditions. This approach has caught on across the industry, with models like the Trek Madone, Lapierre Xelius, and Cervélo Soloist embracing a similar approach.

The S-Works Tarmac embodies this vision perfectly. The Aethos-inspired, rounded tube shapes around the bottom bracket and rear are streamlined for minimal weight. Paired with the aerodynamically optimised front end, featuring the distinctive “Speed Sniffer” aero nose, this is the lightest all-rounder in our test field.

Size	44	49	52	54	56	58	61
Top tube	496 mm	509 mm	531 mm	541 mm	563 mm	577 mm	595 mm
Seat tube	433 mm	445 mm	456 mm	473 mm	494 mm	515 mm	545 mm
Head tube	99 mm	109 mm	120 mm	137 mm	157 mm	184 mm	204 mm
Head angle	70.5°	71.75°	72.5°	73°	73.5°	73.5°	74°
Seat angle	75.5°	75.5°	75.5°	73.5°	73.5°	73.5°	74°
Chainstay	410 mm	410 mm	410 mm	410 mm	410 mm	410 mm	410 mm
BB Drop	74 mm	74 mm	74 mm	72 mm	72 mm	72 mm	72 mm
Reach	366 mm	375 mm	380 mm	384 mm	395 mm	402 mm	408 mm
Stack	501 mm	514 mm	527 mm	544 mm	565 mm	591 mm	612 mm

Racing at the highest level – the spec of the bike

S-Works is synonymous with high-end. Our test bike proves just that, and comes equipped with the very best, high-quality components. Coincidentally, most of the parts are produced in-house by the Californian manufacturer – from the wheels and cockpit, all the way to the saddle – and even the tires bear a Specialized logo. And these components definitely pack a punch.

The Roval Rapide cockpit is all about aerodynamics. The extremely low-profile, slim top bar with a printed tactile texture ensures superb grip and top security, even without bar tape and with sweaty hands. Equally focused on aerodynamics are the Roval Rapide CLX II wheels and 26 mm S-Works Turbo Cotton tires, which are light and thus perfectly aligned with the bike’s all-rounder design. Different rim profiles on the front and rear wheels improve performance in crosswinds, ensuring an ideal aerodynamic balance.

The most polished Allrounder

These wheels have consistently impressed throughout countless comparison tests, though they are slightly more compliant than some of the competition. Specialized completes the setup with a 3D-printed S-Works Power saddle featuring Mirror technology, which provides tailored comfort. The only third-party component is the SRAM RED AXS groupset, which consists of a 48/35 crankset and 10–33 cassette. True to the S-Works ethos, this high-quality drivetrain not only complements the aesthetic but delivers outstanding shifting performance across the board.

Like riding on clouds to the clouds – Specialized S-Works Tarmac SL8 in review

On our test route in the heart of the Dolomites, right on the border between South Tyrol and Veneto, we pushed the S-Works Tarmac through narrow valleys, winding descents, and steep climbs– a dream setup for a lightweight all-rounder like the Tarmac.

The Tarmac SL8 is light and stiff on take-off, with the rear triangle efficiently transferring power to the ground. However, in terms of explosive acceleration, it doesn’t quite match the punch of competitors like the BMC and Canyon. Where the Tarmac truly shines are the climbs: thanks to its low system weight, it powers effortlessly out of every corner with just a little input. Specialized’s finely tuned Tarmac geometry contributes to its all-rounder credentials, making it a modern race bike fit for everything from mountain stages to final sprints on the Champs-Élysées. It’s a thrill for amateur racers, too; without a spacer stack under the stem, the Tarmac becomes a true crit racer. Aerodynamically, it ranks in the upper-middle field–not quite on par with the BMC or Canyon, but right next to the Trek Madone and Wilier.

For climbing enthusiasts and long-distance riders, the Tarmac’s balanced handling is ideal. It offers great control and a solid sense of security, which makes it an excellent choice for both beginners and race-focused veterans alike. The handling is equally well-rounded: balanced and precise without mimicking the razor-sharp steering of the BMC Teammachine.

Everyday comfort and ergonomics also get due attention, as a race bike needs to perform in training as well as during races. The S-Works Tarmac stands out as one of the most comfortable bikes in this test – only the Trek Madone is slightly more comfortable with its innovative IsoFlow system at the rear. Ergonomically, the Tarmac is next level: the comfortable handlebars, the unique 3D-printed saddle, and grippy bar tape ensure an optimal race position and underline its racing focus.

The Tarmac is incredibly versatile and performs well in most scenarios. While it may not offer the uncompromising race character or sheer speed of the BMC and Canyon, this is certainly not a limiting factor in any race.

Tuning-Tipp: A set of stiffer wheels for sharper handling and an extra dose of fun

What type of racer is the Specialized Tarmac SL8 for?

For many, the Specialized S-Works Tarmac SL8 remains the benchmark among race bikes – and rightfully so. With its strong all-rounder DNA, this bike feels at home in nearly every racing scenario, whether you’re climbing, sprinting to the finish line, or tackling classic breakaway stages. The Tarmac delivers 100% reliability, whatever the challenge.
But its performance isn’t limited to the racecourse. Thanks to the optimal blend of lightweight construction, aerodynamic design, and impressive compliance, it’s also an ideal companion for training sessions and group rides. Even on relaxed post-work laps and coffee rides, the Tarmac shines. And with its iconic S-Works logo and striking paint job, it turns heads in the process – even when stationary.

Conclusions about the Specialized S-Works Tarmac SL8 review

The S-Works Tarmac SL8 is a well-rounded high-end racer. Specialized did an outstanding job here, considering every detail meticulously. Weighing in at just under 6.9 kg, with an aerodynamic focus and versatile race character, this bike feels at home in nearly any situation. Professionals and amateur racers alike get a bike that confidently meets any challenge. And believe it or not, for once a Specialized isn’t the most expensive bike in a comparison test! For all these reasons, it gets our clear Best Buy recommendation.

More information at specialized.com.

The test field

This bike was tested as part of the 2024 race bike comparison test – an overview of this comparison test and all other tested race bikes can be found here:

All bikes in test: BMC Teammachine R 01 | Canyon Aeroad CFR | Cervelo Soloist | Falkenjagd Aristos RSR | Lapierre Xelius DRS 9.0 | Specialized Tarmac SL8 | Trek Madone SLR 9 | Wilier Filante SLR

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Words: Calvin Zajac Photos: Jan Richter