Aero, lighter and stiffer – Specialized unveils the new Tarmac SL8

After months of speculation, the American brand has revealed all of the details behind its new flagship model

And here it is. There need be no more scouring the dark depths of the internet to find glimpses of the hotly-anticipated Specialized Tarmac SL8, it is now officially released to the world; free to be ridden by the likes of Demi Vollering and Remco Evenepoel to more professional wins. You can now even buy it yourself (if you have a spare £12k in your pocket…)

The new bike sees some radical differences when compared to the Tarmac SL7, its predecessor. When considering that the SL7 is likely one of the most popular bikes in the world amongst both professional and amateur cyclists, to change up the design this much is definitely a risk from Specialized. The SL7 has already been ridden to numerous victories at the very highest level of the sport, known as the bike that can do it all, be that climbing, sprinting and performing on all terrain in between. Specialized says that the SL8, however, is an improvement on everything we know about the SL7, describing the new model as “the world’s fastest race bike”.

Related: Specialized Tarmac SL8 First Ride Review

In an extensive testing period, it took Specialized’s engineers 53 iterations to come to the eventual SL8 design, using what the brand describes as its ‘Front-Loading Development’ process. Using the layup strategy of the Specialized Aethos and Specialized’s FACT 12r carbon on the new Tarmac SL8 shape, engineers amplified stiffness in certain areas of the bike like the bottom bracket and head tube to create the most compliant ride possible. At the same time, focus was kept on ensuring that the SL8 frame remained lightweight, eventually coming in at 685 grams on the final and 54th iteration. The result is the SL8, which Specialized claims is “16.6 seconds faster over 40km, 15% lighter, 33% improvement in stiffness to weight and 6% more compliant than the 4X World Championship Tarmac SL7”.

When it comes to the improved aerodynamics of the Tarmac, these are evident just by looking at the refreshed frame design of the SL8. Specialized says that its ethos is to put “aero where it matters, not just where it looks good.” The back of the SL8 frame is much more slimmed down at the rear, where aerodynamics matter less. Specialized says that a “deep airfoil down tube and seat tube may look aero, but due to the dirty air they sit in, they create vanishingly small aero gains, but impact weight and ride quality significantly. The result may be slightly more aero in the wind tunnel, but slower in the real world.”

With this in mind, the SL8 features a sharp leading edge on the head tube, made possible by the fact that the steerer tube has been moved backwards. This creates an overall much lower drag shape. The fork also bears a clear resemblance to the Venge fork (Specialized’s now discontinued aero road bike), with a wider crown and deeper blades on the legs. Aero gains on the SL8 also come from the Rapide cockpit that comes equipped with the S-Works version of the SL8, with Specialized saying that it shaves four watts of drag versus the two-piece Tamac bar and stem combination thanks to the minimised hardware on the front of the bars. Specialized offers 15 different bar and stem combinations with the integrated Rapide cockpit, informed by the brand’s Retül fit data.

At the rear of the bike, the Tarmac SL8 seat tube is the same size as the SL7 seatpost meaning that the SL8 has the narrowest, most aero seatpost Specialized have ever made. This means that fast moving air around the legs can easily flow backwards leading to a more efficient ride.

But aerodynamics are rendered less important as a bike is taken into the mountains, which means that keeping the Tarmac lightweight also had to be an important focus for Specialized during the design process of the SL8. Taking inspiration from the Aethos, which is currently the lightest production bike in the world, Specialized says it aimed to ensure that the SL8 was a bike that could perform well when the gradients kicked up but also was an extremely supple ride. At the skinny rear of the bike, weight has been shaved massively on the SL8, and the geometry of this section looks visually very similar to the Aethos. Specialized argues that the weight of the frame can be reduced when the bike isn’t trying to achieve the traditional aerodynamic look with deep tubing, and this is why aero advances have been focused solely on the front of the bike with the aforementioned Front Loading Development ethos. At 685 grams for the frame, Specialized says that the new SL8 is lighter than anything else on the WorldTour.

Weight has also been considered when it comes to frame painting and design on the SL8. Specialized has used new techniques and pigments to create colour with as little paint as possible. Placing the pigment carefully and edge-facing it to get as much colour vibrancy and using a raw carbon base means that paint adds as little weight to the overall frame.

The Tarmac has long been a bike highly regarded for its responsiveness and handling. To improve on this element of the bike from the SL7 was a tall order, but Specialized says it has achieved a stiffness-to-weight ratio improvement of 33% over the SL7 in the SL8  – a big claim. According to the brand, much of this comes from the Front Loading Development process and the inspiration that the brand has taken from the Aethos in tube shaping. Described as the most-supple Tarmac ever, Specialized claim that the SL8 is 6% more compliant even in the saddle, made with the aim of creating a bike that floats over rough roads and gives confidence on tight corners. The SL8 retains the same, popular geometry as the SL7 and the same 32mm tyre clearance to give the bike an impressive amount of versatility. As with the SL7, the SL8 comes in seven sizes, 44cm to 61cm and the same frame is offered across all genders. This is in line with Specialized’s ‘Beyond Gender’ philosophy which argues that Retül fit data shows that creating male and female specific bikes is arbitrary.

The fully-built SL8 comes in three different options; the top of the range S-Works model features the FACT 12r frame level – 100 grams lighter than the 10r frame utilising the most premium lay-up techniques and materials available – and it retails for £12,000 for the full-build and £4,750 for the frame only. The Pro Specialized Tarmac SL8 build is £8000 and the Expert build is £6000. The 10r frameset is £3000. All options are available to purchase on launch.

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