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Specialized launch ‘lightest ever’ S-Works Tarmac SL6 – first ride review

The redesigned Specialized S-Works Tarmac SL6 claims big aero gains, enhanced compliance and a brand new unisex fit that works for people, not genders

Specialized’s Tarmac race bike has been overhauled for 2018. The SL6 version claims to be the lightest and most aero Tarmac ever produced, and both the chassis and geometry have received a thorough makeover.

The Specialized Tarmac is a thoroughbred race bike and has been making headlines for fifteen years. Since 2014 this bike has dominated the Grand Tours, delivered Peter Sagan into the rainbow stripes and amassed over 200 professional victories.

California-based Specialized believe each evolution of the Tarmac – there have been six since it launched in 2009 – has been the very best it could possibly be. So why the upgrade? And what does the new Tarmac SL6, which will be available in six builds (four men’s, two women’s) from £3,500 to £9,500, have to offer?

The news is out: Specialized’s all-round race bike, the Tarmac, has been updated – and this is the lightest version yet

Demands from the top

The Tarmac SL6 has been designed in response to the changing demands of the professional peloton, according to Specialized (you may have seen the shots we brought you of the bike being tested at the Criterium du Dauphine). The dynamics of bike racing has evolved over the last five years and so have riders’ needs – stages are more varied and demand more of the riders.

“The goal was simple, to make the Tarmac better,” says Dr Chris Yu, director of integrated technologies at Specialized, whose research informed the development of the new bike. “Our [professional] riders wanted a lighter, more aero bike that had better handling than before.”

But the changes go beyond the carbon layup and aero innovations. The new Tarmac SL6 also features, “an all, new, performance geometry for people,” says Yu. Not only does this new Tarmac replace the old SL5 but it also replaces the Amira, Specialized’s much lauded women’s-specific race bike. Where before there were separate race bikes for men and women, now there is just one bike but with touchpoints suited to the rider. Yu says this is “a shift in focus from gender, to the way people ride”.

These dropped seatstays are a key feature of the Tarmac SL6, with Specialized seeking to improve the frame’s aerodynamics

Weight loss and aero gains

Bike manufacturers like to jostle for the top spot when it comes to weight and aerodynamics, so how does the Tarmac SL6 stand up? The flagship S-Works SL6 frame claims to be the lightest Tarmac ever made, weighing in at 733g for a size 56cm (the S-Works carbon fork weighs a claimed 325g). Out of the box the S-Works Di2 model will weigh around 6.48kg and the S-Works Tarmac Disc, available later in 2018, will weigh 6.56kg. The limited run S-Works Tarmac Ultralight goes one step further. Featuring paint which weighs just 10g, EE brakes and Roval CLX 32 wheels, it has a claimed complete bike weight of just 6.2kg.

To achieve the S-Works Tarmac SL6’s low weight, Specialized have shaved 30g off the bottom bracket and all cable run internally, whether you choose electronic or mechanical shifting. A new, replaceable derailleur hanger also has a lower, lighter profile. “[The hanger] is designed to be stiffer and better handle shifting loads from the strong, electric derailleurs,” says Stewart Thompson, road product manager at Specialized.

Aerodynamic advantage was also priority when redesigning the Tarmac. To make the desired gains Specialized spent six months in their ‘Win tunnel’ [sic] trying to work out, “how to bring about aero benefits without affecting ride quality”.

Traditionally seen a lightweight all-rounder, the new, more aero Tarmac has a more compact rear triangle and slimmer fork, borrowing heavily from its aero sibling, the Venge. Features include a D-shaped seattube, bladed and dropped seatstays found well down the seattube, and, on the rim brake bikes, sleek, low profile direct mount brakes that are tucked away out of the wind.

If the numbers are to be believed, Specialized claim that compared to bikes in its class for weight, such as the Trek Émonda SL9 (though Trek look set to launch a new Émonda), the Tarmac SL6 is 45 seconds faster over 45km. And, when compared to bikes equal in speed, it is said to be 200g lighter.

Superior handling and compliance

Specialized’s Rider-First Engineering concept was developed in 2014 to address the issue of riders on different sizes of the same bike having different ride experiences. Developed alongside F1 giant McLaren, Rider-First offered a size-specific approach to frame construction that addressed the unique stiffness requirements of different frames.

The Tarmac SL5 featured three, size-specific lower headset bearings but the new SL6 shifts the focus to the fork. Now, each of three Tarmac forks attach to the frame through a 1.5-inch lower bearing, and each steerer tube tapers differently. Smaller forks have a short taper while larger frames feature a fork with a longer taper.

The Tarmac SL6 will be available in six guises, from £3,500 to £9,500

What’s more, as the frame size increases, the rake (or offset) of the fork shortens and the depth and width increases. For example, the fork on a 58cm frame has 3mm less offset and is 12mm deeper and 4mm wider than the fork on a 49cm frame. The rationale behind the approach was three-fold – fine-tuning the fork rather than the headset had a more significant impact on ride quality per size, but it was also a lighter and more aerodynamic solution.

Compliance has also been considered, namely with the seatpost. At the top, where flex is required, the carbon layup is more compliant; while where the tube enters the frame, stiffness is the key.

Geometry for the people

The new Tarmac SL6 is a unisex offering. It replaces the old Tarmac SL5 and the women’s-specific Amira – Lizzie Deignan’s World Championship winning bike. The Tarmac features an, “all new performance geometry for people,” says Yu. Indeed, the only difference between the new men’s S-Works Tarmac SL6 and the new women’s S-Works Tarmac SL6 is the finishing kit and the colours. The women’s model has narrower bars, shorter cranks, a women’s-specific Oura Pro 155 saddle and, naturally, a splash of pink.

The decision to phase out the women’s-specific Amira – it remains at the lower end of the range – was based on data gathered by Retül, which showed the bike fits of men and women who raced, or rode with an aggressive set up, were surprisingly similar. The conclusion was that rather than build two bikes with a similar geometry, both sexes could be served by a single geometry. It’s a controversial move, especially given that last year, at the launch of the Ruby and Roubaix, gender-specific geometry was all the rage, but the data does seem to back the theory that racers pretty much ride the same, regardless of whether they are a man or woman.

With the women’s-specific Amira no more, the Tarmac is now effectively a unisex frame

How this new geometry plays out is most noticeable on the smaller sizes, where the toptube is subtly shorter when compared to the 2017 Tarmac SL5; on a size 49cm the reduction is 10mm and on 52cm the toptube is 6mm shorter. The other obvious difference is the headtube length, which is increased from 100mm on a 49cm frame to 115cm, and from 120mm to 126m on a 52cm frame. There have also been micro adjustments throughout the entire front end with subtle changes to headtube angle, stack and reach, all made in a bid to achieve a utopian balance of handling and stability.

The new geometry also responds to the trend for running wider tyres, making it possible to ride up to a 33mm tyre, should you feel a Strade Bianche moment coming on.

The ride – fast, compliant, nimble

Within minutes of the first ride, the S-Works Tarmac SL6’s superb handling is obvious. This is a light bike – a 56cm weighs 6.48kg – yet it is firmly planted on the road. Driving the Tarmac through a left-hand bend early on the ride is a pleasure and there’s a directness that comes from the short chainstays and the compact wheelbase (985mm). This is a bike that feels ready to go at a millisecond’s notice and it certainly delivers when asked – thanks to the stiff bottom bracket area there’s a sense that every watt of power is being transferred into forward motion.

Out of the saddle, the Tarmac SL6 is nimble but sure-footed, something that comes as a bit of a surprise given the noticeable slimmer-profile tubing. Gone is the beefed up headtube, tapered toptube and oversized bottom bracket but stiffness and responsiveness remain superb.

It’s on fast flats and descents that the Tarmac SL6’s aero assets are more noticeable. Indeed, with the addition of aero profiling there’s a sense that the SL6 has caught up and even over taken some of its closest rivals when it comes to the all-round race bike. By borrowing appropriately from the Venge, the Tarmac has moved into a different space that marries low weight, racy responsiveness and aerodynamics.

Most noticeable, especially to anyone who has a ridden a previous version of this bike though, is the difference in compliance. Gone is any grit-your-teeth stiffness and in its place, is a bike that soaks up pretty much anything you can chuck at it. Our test took us on a 5km stretch of gravel, which the S-Works Tarmac SL6 took in its stride.

The Tarmac SL6 provides a beautifully balanced ride

For a bike that retails for £9k, the spec should be top notch – and it is. Shimano’s premium Dura-Ace Di2 9150 11-speed groupset is the star of the show and there are no compromises or hidden downgrades. In fact, the only deviation is the S-Works carbon fibre crankset, which is lightweight and super-stiff. The 52-36t semi-compact chainset paired with an on-trend 11-30t cassette gives the best of both worlds when it comes to gearing for climbing and sprinting.

Braking is also impressive. The Dura Ace 9110 calipers are predictable and dependable, offering excellent modulation and the shallow drop on the 125x75mm Specialized Comp bars bring the levers within easy reach both from the hoods and in the drops.

The Roval CLX 50 wheelset has received rave reviews, thanks to a claimed weight of 1,375g – remarkable for a mid-depth wheelset – and they complete a top-notch spec sheet.

Six builds

The Tarmac SL6 will be available in six different builds; four for men and two for women. ranging from £9,500 for the S-Works Tarmac Ultralight to £3,500 for the Tarmac Expert, made from Specialized’s second-tier 10r carbon fibre.

Here’s how the range looks:

Specialized Men’s S-Works Tarmac Ultralight – £9,500
Shimano Dura-Ace Di2 9150, Roval CLX 32 wheels

Specialized Men’s S-Works Tarmac – £9,000
Shimano Dura-Ace Di2 9150, Roval CLX 50 wheels

Specialized Men’s Tarmac Pro – £5,750
Shimano Ultegra Di2 8150, Roval CL 50 wheels

Specialized Men’s Tarmac Expert – £3,500
Shimano Ultegra 8000, Roval SLX 24 wheels

Specialized Women’s S-Works Tarmac – £9,000
Shimano Dura-Ace Di2 9150, Roval CLX 50 wheels

Specialized Women’s Expert – £3,500
Shimano Ultegra 8000, Roval SLX 24 wheels

The men’s women’s S-Works frameset will also be available for £3,250, while there’s also the option of a Peter Sagan paintjob for £3,350 or the Ultralight frameset for £3,450.

Specialized will also continue to offer a range of more affordable Tarmac SL4 and SL5 bikes, in rim and disc brake versions.

The bottom line

In its nine-year history, the Tarmac has been through many iterations but it has always remained a true racing bike. This redesign has been informed by continual feedback from some of the world’s best riders, but also by the data of bike fit, which like any science continues to evolve over time.

Ultimately, our time on the S-Works Tarmac SL6 to date has revealed it as a toned, honed, nipped-tucked and pimped-up version of what was already a stand out machine. Specialized’s approach to the design has been clinical -anything superfluous, inefficient, outdated, or not up to scratch has been assigned to the scrap heap. What results is a razor sharp, nimble and yet beautifully compliant ride that will undoubtedly keep adding to the Tarmac’s winning tally.

Website: Specialized