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Specialized S-Works Tarmac SL6 review

5 Feb 2018

Specialized aims for the complete World Tour racer with improved aerodynamics, stiffness and a frame weight of 733 grams

Cyclist Rating: 
A complete all-rounder - phenomenally fast, with precise handling and versatile enough to continue riding when the tarmac ends

Buy the Specialized S-Works Tarmac SL6 from Tredz here

The Specialized Tarmac isn’t just a model of bike – it’s a dynasty. The line began in 2003, and since then the various iterations of the Tarmac have claimed victories at every Grand Tour, multiple World Championships and Olympic Road Races, and even a handful of the cobbled Classics.

While on the surface the new Tarmac may look similar to its predecessor, with a near identical geometry for a 56cm frame, every single tube has changed in shape.

Perhaps most notably, the seatstays have dropped in height and are now reminiscent of the back end of the Venge ViAS.

The seat tube also uses a more aerodynamic D-shaped cross-section along with a cut-out for the rear wheel, which Specialized claims has contributed to a considerable reduction in drag.

The result is that Specialized’s ‘Win Tunnel’ (see what they’ve done there?) data shows this new Tarmac to be equal with the previous generation of Specialized Venge in aerodynamic terms.

‘Our tests show the new Tarmac saves 45 seconds over 40km compared to the current generation of Trek Émonda or Cannondale SuperSix,’ says Chris Yu, Specialized’s director of integrated technologies. Of course, we’ve only got his word for that.

One-stop solution

The gains in aerodynamics reflect a wider desire to make the bike more versatile for Grand Tour pros – a one-stop solution to racing.

‘The dynamics of pro racing have changed over the years,’ explains Yu. ‘Every 10km the decision on which of our previous bikes was most suitable would switch.

‘So that’s why we have taken the decision to make a bike that is appropriate across all different types of stages and terrain.’

With a weight of 733g in a size 56, the Tarmac could claim to be one of the lightest-ever aerodynamically orientated frames (30g lighter than Pinarello’s F10 X-Light in a size 53).

The revised model is about more than just the frame, though. Every component is a Specialized product, save for the drivetrain and brakes.

In that sense it’s important to consider the way in which the Tarmac has been adapted to its componentry – and specifically the tyres.

The S-Works Tarmac comes specced with a 26mm Turbo Cotton tyre that measures 29mm in profile when coupled with the Roval CLX 50 wheels (the bike is capable of fitting up to 31mm tyres).

This is a shift not only in design but in the identity of the bike, opening up more varied types of terrain, be it cobbled Classics, gravel tracks or smooth roads.

I used the S-Works Tarmac on all these surfaces, and it never failed to impress. 

On the Tarmac

I rode the previous generation of the Tarmac, the SL5, a great deal, and came to consider it a benchmark by which to judge other endurance racers – specifically when it came to handling.

As such, seeing it so drastically changed, and hearing that the handling had been altered, left me a little apprehensive.

At first the new Tarmac felt very different. The wider tyres, more rigid design and more aerodynamic curves made it faster, racier and a little less compliant than I expected.

Over time, though, it became clear that the SL6 was an improvement over its predecessor.

Aerodynamics are tough to quantify without a wind-tunnel, but the Tarmac definitely held speed well at around 40kmh, and felt more akin to a fully aero road bike in pure speed terms.

However it was the rigidity of the new frame that struck me the most on my initial ride.

I just wanted to repeatedly stamp on the pedals and sprint all-out (just look at Sagan’s finish line sprint at the Worlds to see how well it copes under thousands of watts).

Pulling away from traffic lights I occasionally found the front wheel lifting off the ground, so eager was I to eke out every watt I could.

Well tuned

That stiffness seemed well tuned from front to rear, and I was a little shocked by how rigid the bottom bracket was. Under pressure it seemed not to flex at all, but to transfer power directly to the road.

That stiffness coupled nicely with finely tuned geometry to create supremely precise cornering and ample stability on descents.

Indeed, handling was a big target for Specialized with the new Tarmac, and the manufacturer worked closely with its WorldTour teams to target sharper handling and better feedback from the road.

The consequence was a revised approach to scaling geometry to sizing, and doubling the number of plies in the carbon to tune the behaviour of the material itself.

Specialized, unsurprisingly, claims team members have all reported an improvement in handling. For my part, I was startled by how palpable that change was.

To put it in the clearest way I can, the Tarmac made me feel as though I could make any corner at any speed.

That stability and confidence equally lent itself to riding on gravel or chalk roads, and I found myself confidently sprinting off-road on terrain I wouldn’t usually dare to take a road bike onto.

Much of the credit has to go to the wide Turbo Cotton tyres. They feel and perform fantastically, but the caveat is that they’re best preserved for dry summer days, a point brought home to me by five punctures on wet roads.

Specialized pricing

If there is one complaint, it’s with the pricetag. At £3,250 for the frame, to reach the RRP of £9,000 leaves £5,750 to cover the Roval wheelset, Shimano groupset and own-brand finishing kit.

By my calculations, buying the fully built bike doesn’t offer much discount from getting the components separately at full retail price.

In that financial sense, Specialized’s 2018 Tarmac Pro is a much more appealing bike. With Roval’s slightly-lower spec CL 50, Ultegra Di2 and a slightly lower grade of carbon, it comes in at £5,400.

I’m sure there’s a slight performance cost, but it will likely be hard to discern.

That’s where my criticism of the S-Works Tarmac ends. There are no elements of the design or spec I could imagine wanting to tweak. Like a budding juvenile infatuation, I wanted to spend absolutely all my time with the Tarmac.

My rides were longer, faster and my riding companions inexplicably slower when I was aboard the Tarmac.

Buy the Specialized S-Works Tarmac SL6 bike from Tredz here


Groupset Shimano Dura-Ace Di2 9150
Brakes Shimano Dura-Ace 9110 direct mount
Chainset Shimano Dura-Ace Di2 9150
Cassette Shimano Dura-Ace Di2 9150
Bars S-Works SL Carbon Shallow Drop
Stem S-Works SL alloy
Seatpost S-Works Fact Carbon Tarmac
Saddle S-Works Toupé
Wheels Roval CLX 50
Weight 6.39kg (size 56cm)



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