In its short life so far, the new Specialized Tarmac SL6 has already claimed two road world championship titles and 5-star reviews pretty much across the board, and so it begs the question can it be made any better? Specialized have answered that question by redesigning the Tarmac around disc brakes to create a bike that lets you go fast uphill, downhill and everywhere else - their most complete race bike just got more complete.
Looking for top notch disc brake performance, but S-Works a little out of your price range? Make sure to check out the new, expanded Tarmac Disc range.See the Tarmac Disc range >
Let's start by talking about the 'disc' part of the Tarmac Disc. Sitting alongside the rim brake version premiered late last year, if you're in the market for an all-round race machine there's now a Tarmac to suit your preferences. By redesigning the frame to accommodate discs alongside the rim brake model both bikes are evenly matched on aero performance, speed and handling so there's no compromises regardless of which model you prefer. Geometry, developed by Retul, matches the rim brake Tarmac while the S-Works Tarmac Disc weighs in at 800g for the frame with the fork at 338g. Built up, the complete Tarmac Disc, including the S-Works Power Cranks, comes in at 6.65kg compared to 6.36kg for the rim brake version - certainly not a heavyweight by any means.
Over the last few years as the popularity of disc brake road bikes has grown, that all important vanity aspect has got more and more refined as well. While traditionalists will still bemoan the visual impact of disc brakes on a road bike, the rapid escalation in technology has seen disc brake road bikes quickly improve their aesthetic and there's no doubt that the new Tarmac Disc is a looker. Could this be the best looking disc brake road bike yet? We think it might be.
Redesigned and refined frame
The Tarmac gets the 'Rider-First Engineered' treatment, so each of the seven sizes which Specialized offer get the same tuned ride as a result of hours spent poring over every tube shape and thickness. The result is that whether you ride a 49cm or a 61cm, you should get exactly the same level of responsive ride handling and frame stiffness.
For Specialized to hit their own required stiffness and handling targets across every size, they've added over 200 extra pieces to the carbon layup for the new Tarmac Disc compared to the previous generation. Each frame gets its own unique S-Works Fact 12r carbon fibre layup, with different ply arrangements, orientations, thicknesses and quantities of material in specific areas. The seat tube on a 61cm, for instance, needs a much longer carbon ply than a 49cm frame so to ensure consistent ride feel across the sizes and so the larger frame uses a thicker, stiffer carbon fibre. The same goes for the bottom bracket - to ensure that famous Tarmac �snap� is the same across all sizes, the bottom bracket needs to meet different stiffness values depending on size so the 61cm frame has three-times the amount of extra-long pitch fibres in specific areas around the bottom bracket when compared to a 49cm frame. While the bottom bracket handles power transfer, the Tarmac's pin-sharp handling comes from the stiffness of the head tube. With larger sizes, the longer tubes need more stiffness to meet the same standards as smaller frames so with the Tarmac, plies have been added in different orientations and precise locations to let you rail corners regardless of size.
Aero is everything
At the cutting edge of Grand Tour road bike performance it isn't just enough to be the lightest or stiffest - you need to be fastest too. Aerodynamically identical to the rim brake version, the Tarmac Disc claims to have the perfect balance of aerodynamics and handling with a 45 second saving over 40 kilometres compared to other lightweight bikes in the same weight category. That figures makes it as aero as the first Venge, itself a landmark performer in aerodynamic terms at the time.
This extra aero impetus is the result of a six-month iterative process combined with the knowledge Specialized have garnered from countless aero projects, computational fluid dynamics and real-world testing. Through this, three areas were identified where 'free speed' could be gained without sacrificing ride feel - the forks, seatstays and seatpost and tube. The full FACT carbon S-Works fork has been built around a truncated airfoil profile to ensure maximum efficiency as the first part of the bike to hit the wind which, when combined with a tapered construction, provides the perfect balance of aero gains and handling prowess. Moving towards the rear of the bike, the seat tube gets the same airfoil treatment with a distinctive D-shape built up with engineered flex and a progressive carbon layup that gets stiffer towards the bottom bracket. Last but certainly not least, the new Tarmac has borrowed the dropped seatstays proven on the Shiv TT bike and Venge ViAS aero bike, which hides the tubes from the wind without sacrificing stiffness, compliance and responsiveness.
S-Works Power Cranks
With an 'S' branded power meter spotted on the Dura Ace cranks of triple World Champion Peter Sagan's Tarmac earlier this year, the S-Works Power Crank has officially broken cover and comes as part of the new S-Works Tarmac Disc. Providing dual sided power measurement and developed with 4iii, the S-Works carbon crank weighs in at just 440g making it the lightest power meter available.
On top of that low weight, Specialized also claim that the S-Works Power Crank is the most accurate power meter available. Starting out life in Specialized's Human Performance team, the power meter has been developed and tested for maximum accuracy in real-world conditions with 1.5% better accuracy at every power level, cadence, gear, pedal offset and riding position. The cranks work with ANT+ and Bluetooth so should connect up with most devices, and comes with easy set-up and diagnostics through Specialized's own Power app. The Power Cranks are sold as a complete carbon crankset with dual or single sided power measurement, but a Shimano Dura Ace version of the power meter, and a lower price, single-sided Ultegra upgrade.
On launch, you'll find men's and women's versions of the S-Works Tarmac Disc, both of which come equipped with FACT 12r carbon fibre frames and forks, Shimano Dura Ace Di2 shifting and hydraulic braking, Roval CLX 50 Disc carbon wheels shod with 26mm Specialized Turbo Cotton, and - of course - the new S-Works Power Cranks. In addition there's two framesets available in eye-catching colourways.
Legendary performance now available with the confidence of disc brakes - Specialized's most complete race bike just got mroe complete.
- Frame - S-Works FACT 12r Carbon Fibre
- Fork - S-Works FACT Carbon Fibre
- Drivetrain - Shimano Dura Ace Di2 9150 22 Speed
- Brakes - Shimano Dura Ace Di2 9170 Hydraulic Discs
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