Specialized S-Works Tarmac SL6 Disc review

First bike brand with its own power meter — on an excellent disc race rig

Our rating 
4.5 out of 5 star rating 4.5
GBP £9,250.00 RRP | AUD $13,500.00 | USD $11,000.00

Our review

Redefines 'house brand' quality with high-end Specialized parts - including a power meter
Buy if, You love the Tarmac ride and want an elite power-meter-equipped disc race bike
Pros: Crisp handling, comfortable ride, top-shelf hydro/digital 9170, integrated power meter — ready to train and race without modification
Cons: Price, meter is a good tool but not perfect
Skip to view product specifications

The Specialized-branded power meter may be the headline, but the main story here is that the Specialized Tarmac SL6 Disc comes dressed head-to-toe in house components that meet, if not exceed ,the quality of many specialty brands.

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Oh, and the bike is a delight to ride, too, with its well-honed race geometry now complemented by a slightly softer-riding rear end and enhanced aerodynamics, plus Shimano’s impeccable Dura-Ace 9170 hydraulic/Di2 group.

Specialized is redefining what a ‘house brand’ can mean as a top-level contender with this bike. Not only in the cockpit components or its well-known saddles and tires, but now, notably, a power meter. Specialized is the first bike brand with its own meter to come stock on a bike.

Specialized Tarmac SL6 Disc highlights

  • Shimano Dura-Ace 9170 group, with 52/36 rings and a lovely 11-30 cassette
  • Size-specific frame and fork layups
  • Claimed to be as aero as the original Venge
  • 30mm tire clearance (comes with 26mm S-Works Turbo clinchers)
  • Claimed 14.65lb / 6.65kg weight for 56cm with the lightest paint (test bike is 14.99lb with standard paint and saddle with metal rails instead of carbon)
  • Specialized-branded Power carbon-arm power meter with left/right data
  • Roval CLX 50 wheels with CeramicSpeed bearings
  • Redefining ‘house brand’ quality
Dropped seatstays are a trend in performance race bikes
Dropped seatstays are a trend in performance race bikes
Ben Delaney / Immediate Media

Every piece of the equation — including dialing in the rider

We’ll get to the bike as a whole shortly, but first let’s look at the individual pieces.

The story here is how Specialized — like Trek, Cannondale, Giant and others — is making top-level components. Aside from the Shimano group, everything on the bike is Specialized.

With the Retül fit brand now part of Specialized, the California company not only takes care of the touch points — saddles (and shorts), bars (and tape), and shoes (and insoles) — but also how every element in the man/machine equation comes together.

Power meter equipped, innovative and a delight to ride

For this review, I went through the Retül process with co-founder Todd Carver, who estimates he has done 7–8,000 fits in his career.

The last time I had a Retül fit was before an Ironman, where I had no clue about what a proper triathlon position should be. Retül put me higher and much further forward than I had been, resulting in a much more comfortable position and an age-group second place on the Ironman Boulder bike leg. (I was pretty much last in the swim!)

While Retül co-founder Todd Carver didn't change my bike setup, he did scoot my shoes slightly forward on the pedals. Retül uses its own motion-capture software for fits, with each key point marked on the body and tracked in 3D
While Retül co-founder Todd Carver didn’t change my bike setup, he did scoot my shoes slightly forward on the pedals. Retül uses its own motion-capture software for fits, with each key point marked on the body and tracked in 3D
Immediate Media

For road fits, however, I do have a clue about what works for me and what doesn’t. Todd didn’t change anything from my normal bike dimensions (120mm stem, 10mm drop), but he did change my cleat position, scooting my feet forward on the pedals about 8mm and then moving my saddle forward the same amount.

I have always centered my cleats under the ball of my foot. Todd suggested centering it between the ball and the fifth metatarsal (the bony protusion on the outside of your foot).

How Specialized parts stack up

The cockpit components — the S-Works carbon shallow bar, the alloy stem and the Tarmac seatpost — are on par with the best out there. I would happily run a Specialized seatpost or handlebar on any bike.

As for the stem — can you really tell a difference in top-end alloy stems? I can’t. The stock shallow bar has a slightly flattened top section, which I like as it dispersed pressure across the palms, and the drops also have a subtly flattened contact patch with your hand.

For saddles, Specialized not only meets but beats the majority of the options out there on the market. I used my tried-and-true Power Pro for this test. The stock S-Works Ronin is also an excellent option that works for many riders. Specialized offers most saddles in multiple widths, and the Retül process will dial you in if you don’t already have a favorite.

Ovalized bars can be tricky as they add another fit element to consider when setting bar and shifter angles, but dispersing pressure across the palms is generally a good thing
Ovalized bars can be tricky as they add another fit element to consider when setting bar and shifter angles, but dispersing pressure across the palms is generally a good thing
Ben Delaney / Immediate Media

For wheels, you have the Roval CLX50 carbon clinchers. The first carbon clinchers I ever rode were Reynolds-made Rovals — and they both failed from heat delamination on steep and windy mountain roads in Spain. That was years ago, and Specialized has since invested heavily in its own R&D and production.

Now I believe they are roughly on par with the likes of a Zipp or an ENVE. BikeRadar’s experience with Roval wheels in general has been that they are often a little lighter than the competition, but not always as durable.

In terms of aerodynamics, that is pretty darn hard to judge. I am of the mind that while general categories are easy enough to differentiate (deep wheels absolutely feel faster than box-rims), similar aero rims are very hard to tell apart by pedaling around.