Specialized launches the S-Works Tarmac Disc and officially reveals its power meter

At varying times over the last few months we've been teased these two products, but at long last Specialized has revealed the S-Works Tarmac Disc and its power meter.

The latterr was first spotted on the Bora-Hansgrohe bikes at the Tour Down Under, while the Boels-Dolmans team raced aboard the disc equipped Tarmac at the same race.

We'll start with the new bike, which in its looks is identical to the rim S-Works Tarmac that we know and love. In fact, both the rim brake versions and the disc brake versions have identical geometry thanks to Specialized's Retül fit technology and its Rider First Engineered designs.

It's a concept that, in theory, allows all bikes regardless of size or disc brakes to have the same ride feel.

It means the bike's ride characteristics stay the same between the smallest size (44) and the largest size (61). There are no women-specific models, just smaller sizes and different layups to maintain the same ride feel.

The two bikes do have different chainstay lengths, which on the disc version are now set at 410mm across all sizes. Previously, it was between 405 and 410mm depending on the size. There's also a new "Flush Axle System" in use on the disc brake model, with 10x100mm spacing up front and 12x142mm on the rear.

Interestingly, when you buy the bike you get two different types of thru-axles. There are DT RWS levers and flush, bolt-on axles. The flush axles are 30g heavier than the levered version.

The addition of the discs has increased the weight slightly from the rim brake model. The S-Works Tarmac Disc now weighs a claimed 6.65kg, whereas the the rim brake version weighs 6.36kg. However, the weight of the disc version does also include the S-Works Power Cranks, but we'll come back to this later on.

Specialized says that aerodynamically, the bikes are identical. What's surprising is that it has been able to make the bike this aerodynamic without changing the frame construction in anyway. Usually bike companies find they have to compensate for the discs by altering elsewhere in the frame.

Ask it, and the brand would probably attribute this to the fact it has been been working on the disc brake model for over five years, developing it in conjunction with the rim brake model. However, it hasn't provided us with any contextual data or figures so we're taking the claims with a pinch of salt.

Specialized also assures us that the frame will gobble up a tyre that's 30mm when installed and inflated. The full bikes ship with 26mm Specialized turbo cotton tyres.

Specialized Tarmac Disc: Pricing and availability

Currently, the S-Works Tarmac Disc and the frameset are the only models available and they're in stores right now (from the 14th March).

The S-Works Tarmac Sl 6 Disc is the only complete model currently available and costs £9,250, which includes Specialized's new power meter.

It's also available to purchase as a frameset for £3,250, which includes the headset, seatpost, CeramicSpeed BB30 bearings, cable routing items, seat clamp and a rear derailleur hanger.

Specialized power meter

We first saw Bora-Hansgrohe riding a power meter at the Tour Down Under that was not so subtly hidden underneath the covering of a massive Specialized S.

That was, in fact, Specialized's Dura-Ace dual-sided power meter, one of four models the brand is releasing. It's the most expensive model, retailing at £1200. As we mentioned, it's dual-sided, with one pod on the inside of the non-driveside crank, while the other sits in the chainrings. Specialized says it has a +/- 1.5% accuracy rating, and it's available in crank lengths from 170mm, 172.5mm and 175mm.

As you might expect, Specialized also has the power meter available with its own carbon S-Works road Cranks. It'll cost £995, without the Specialized or Praxis chainrings which are sold separately. It will also fit OSBB, PF30 and "most" BB30 bottom bracket frames.

The brand says it's the lightest on the market, weighing just 440g for the 172.5mm crank length version. It's also available with 165mm cranks through to 180mm cranks. There will also be a single sided Specialized Power Crank that will cost £650.

As equally exciting is the Shimano Ultegra R8000 upgrade kit that Specialized is making available "later in the year". It'll cost £400 and is the non-drive side crank equipped with a single-sided version of the new power meter. It's as easy to install as just whipping your old crank off and putting this one on. Again, it's available from 170mm, 172.5mm and 175mm.

Specialized told us that internally, the power meter has 4iiii's technology, but that the brand wasn't happy with the quality of the casing. Considering that the power meters will be jet washed on the pro bikes everyday and subjected to intense hot and cold temperatures it spent a long time creating a product that was properly weather sealed.

Going forward, the top end S-Works bikes will come with the new power meter as standard on the bike. The Pro models will receive it from 2019.