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July 1, 2017
Photography by James Huang and Anne-Marije Rook
The Specialized Tarmac SL 5 has a proven record of success with well over 200 professional wins since 2015, but the sixth-generation Tarmac SL6 nevertheless gets a full makeover for 2018 that includes a more aerodynamic shape, a lower weight, all-new gender-neutral geometry, and even a substantially smoother ride than before.
The new Tarmac SL6 has already made appearances at Tour de Suisse and the OVO Energy Women’s Tour, and now Ella Editor Anne-Marije Rook has put it through its paces for herself.
Modern races — even Grand Tours — increasingly require riders to be all-rounders, with the ability to climb, descend, stick their noses into the wind, and still have a kick for the finish. The Tarmac has always been Specialized’s flagship road racing platform, but as professional cycling has changed, the company saw fit to change the Tarmac into a similarly well-rounded machine.
The previous Tarmac was all about low weight and high stiffness with a more gracefully rounded aesthetic and that trademark sloping and arching top tube, but the new Tarmac SL6 is all straight-edged and sharp with a slimmed-down head tube, flatter fork blades, and a deeper-section, D-shaped seat tube and seatpost.
Borrowing the design from its Shiv and Venge aero siblings, the rear triangle has also been lowered, with seat stays that now meet the seat tube further down than before.
Specialized insists this profile doesn’t just look fast; it is fast.
According to road product manager Stephanie Kaplan, in-house wind tunnel data gives the Tarmac SL6 a 45-second advantage over 40km as compared to more traditional round-tubed bike like a Trek Emonda or Cannondale SuperSix EVO, putting it roughly on-par aerodynamically with Specialized’s previous-generation Venge dedicated aero road bike.
The sixth-generation Tarmac has not only gotten more aerodynamic; it’s gotten lighter, too. Claimed weight for a 56cm S-Works frame is just 733g.
Logoing is pleasantly sparse, and also reflective on this S-Works model.
As compared to the fifth-generation Tarmac, this new SL6 has a wider and taller top tube – something Specialized says was key to maintaining the frame’s torsional stiffness while simultaneously improving rider comfort.
Specialized’s trademark hourglass-profile head tube isn’t nearly as hourglass-like as before.
Specialized has gone back to using the same lower steerer tube diameter on all sixth-generation Tarmacs, instead varying the fork blade sizes to provide a more consistent ride quality across the size range.
Other highlights may not be as apparent to the casual observer at first glance.
The Tarmac SL6 is lighter than the SL5, with a claimed weight of just 733g for a 56cm frame. An impressive 30g weight savings came from the redesigned press-fit bottom bracket shell alone, which now uses a pared-down plastic guide instead of molded-in channels for the internally routed cabling.
A switch to direct-mount rim brakes saved a few additional grams, while also adding room for tires up to 30mm-wide; a disc-brake version is pending, too. A special ultralight build will even use a minimalist paint finish that supposedly adds just 10g to a raw frame.
Specialized says the D-shaped seatpost and seat tube and the dropped seat stays are not only faster in the wind tunnel, but also more comfortable on rough roads since they flex more than rounder shapes. But yet that added comfort hasn’t come at the expense of efficiency; if anything, Specialized claims the Tarmac SL6 is actually more refined for each given size than before while maintaining the SL5’s outstanding stiffness traits.
Previously, Specialized received feedback that small riders found the bike’s responsiveness too twitchy while tall riders said it wasn’t quite stiff enough. According to integrated technologies director Chris Yu, each Tarmac SL6 uses almost twice as many individual pieces of raw carbon fiber than the SL5 to better tune the ride quality, and while every frame now uses the same 1.5-inch tapered steerer tube diameter, the fork blades themselves vary by size so that every rider experiences the same ride feel — from a 1.5m-tall, 50kg woman all the way up to a 1.9m-tall, 100kg man.
Dropped seatstays are becoming increasingly common, with proponents saying the offset junction helps the seat tube flex more on bumps than a more traditional configuration.
The D-shaped seatpost and seat tube not only perform better than round shapes in the wind tunnel, according to Specialized, but are also more comfortable.
Whereas the fifth-generation Tarmac bottom bracket shell (at right) incorporated housing guides directly into the carbon structure, the sixth-generation version uses a simplified setup that saves weight.
With such a huge spread in sizes between the smallest and largest options, it can be quite a challenge to provide both riders with the same ride quality.
The new bottom bracket shell instead uses a small plastic sleeve to keep rear disc brake hoses and drivetrain wires from rubbing on the crankset spindle.
For years, Specialized has been beating the drum of women’s-specific bikes with unique frame geometries, but when it comes to the 2018 product line, Specialized welcomed a shared platform geometry, saving goodbye to the much-loved Amira and introducing a women’s Tarmac.
According to Kaplan, that previous approach was based on decades-old anthropomorphic data collected by the United States Army, not bicycle fitters. But since the acquisition of Retül and its digitised fit protocol in 2012, Specialized can now draw from over 40,000 sets of consistent and accurate position files. Based on that more application-specific information, Specialized engineers have instead determined that a single gender-neutral frame geometry can work just as well.
“Instead of co-opting the men’s frame, we made one frame for everyone,” Kaplan said. “We went back to the drawing board to create the best bike for a performance-minded rider, no matter the gender. It’s about being purposeful and based on fact.”
As a result, the SL6 geometry actually now comes closer to the Amira than the SL5, but that doesn’t mean the women’s and men’s Tarmac SL6 are one and the same. Men’s and women’s Tarmacs will still be differentiated by touch points, such as handlebar width, saddle models and sizes, and stem and crankarm lengths. The size range has expanded, too; Tarmac SL6 frames are now available from 44cm up to 61cm, all with standard 700c wheels.
As expected, men’s and women’s bikes will also be visually distinguished with specific paint jobs, and on higher-end models, those differences may be as subtle as decal colour. In a quick poll among the journalists present at the launch, it appeared that the red-pink gradient decals on the women’s S-Works Tarmac SL6 was just as popular with the men in attendance as the women, and I wouldn’t be surprised if that frameset will sell just as well to both sides.
The women’s version of the Tarmac SL6 comes with narrower handlebars, shorter crank arms, the Oura saddle and different decals.
The women’s S-Works Tarmac comes with these flashy decals
The women’s Tarmac comes with these flashy decals
Prefer to have your S-Works Tarmac SL6 with a bit more color? Specialized will offer a few limited-edition paint jobs as well.
I test-rode a flagship S-Works model, equipped with Shimano Dura-Ace Di2 and the zippy Roval CLX 50 carbon clincher wheels. I tried both a 52cm and a 49cm bike, and could have ridden either one, but the 49cm ended up suiting me best. In switching to the smaller bike, however, I did encounter a little bit of toe overlap, which is uncommon for me.
But after receiving the “lightest, stiffest, fastest” spiel from the lovely Specialized folks earlier in the day, I was keen to touch, feel and ride the bike for myself. And so, just like anyone does when they look at a bike in a showroom, I found myself lifting the bike up from the ground to feel its weight.
Sure, it felt arbitrarily light, but it wasn’t until I actually got on the bike that I noticed just how light the bike is — and with that does come a learning curve.
Feather-weight race bikes are often also highly agile and responsive, to the point that some might describe them as twitchy — you so much as sneeze and the bike practically jerks across the road. Agility, stiffness and responsiveness are all desirable qualities in high performance bikes, but it can also be a detriment to those with lesser handling skills; the bike is going to do exactly what you tell it to, mistakes included.
With that said, for those capable bike handlers, it’s that very playfulness that puts a smile on faces as you power away from companions or throw the bike into the corners of a high-speed descent.
The responsiveness of the new Tarmac SL6 was quick and sharp, as I have come to expect from Amiras I have ridden before. Likewise, the light-and-stiff Tarmac is a willing climber, with my climbing ability being the only limit to its capability.
Bombing it down the descent that followed, I was curious to see what the bike would do. I factored in a little bit more caution than I would on my regular bike, but the front-end stiffness gave me excellent steering response while the bike felt grounded and stable.
This again became palpable as I jump out of the saddle for city-limit sprints. The bike sprung into action, surging forward when called upon, while the rear stayed pleasantly grounded.
There is absolutely no mistaking this bike for what it is – a purebred race machine – but thanks to the compliance gained from the revamped seatpost, the ride felt significantly less harsh than many other aero race bikes. It may be my favourite new feature on the Tarmac.
The seatpost paired with some 26mm tyres meant that 125 kilometres with some rough roads and mixed terrain were absolutely no problem for the bike or my lower back — and again, should you want to go full-cush, the frame does have clearance for 30mm tyres.
Even by just going on that one ride, I am confident in saying that the S-Works Tarmac SL 6 will go a long way in meeting the demands of Grand Tour riders while delighting anyone looking for a high performance bike to get the most out of their rides.
The S-Works Tarmac SL 6 (men and women’s) as reveiwed here retails at USD $10,000 or USD $4,000 for the frameset. The limited edition ultralight Tarmac with Di2 will retail for USD $10,500 or USD $4,250 for the frameset alone.
If nothing else, the new Specialized Tarmac has gained an even-sleeker appearance than before.
Fully internal wiring arrangements may look cleaner, but this setup isn’t bad and is easier to service.
Instead of molding a bridge directly into the seatstays, the new Specialized Tarmac SL6 uses a small bolt-on carbon fiber bridge.
One additional benefit of the taller top tube profile was having enough room inside for an internal seatpost binder.
Officially, the new Tarmac will clear 28mm-wide tires.
Direct-mount brakes are used front and rear on rim-brake models. The top-end ultralight version will use calipers from boutique brand eecycleworks.
The fork crown sports an unusually low profile that helps tuck the front wheel up closer to the bottom of the down tube. Specialized says this helps improve the bike’s aerodynamics.
This area is especially sleek on the disc version.
A disc-brake version is in the works, too, although that one is still being finalized.
The front brake hose is routed through the fork blade for a clean and tidy appearance.
160mm-diameter rotors will come standard up front
Flat-mount calipers are featured front and rear for improved stopping performance, along with 12mm-diameter thru-axles that not only help combat wheel movement in the frame, but locate the hubs more consistently to prevent pad rub after a wheel change.