With the launch of the new S-Works Tarmac Disc, we’re arrived at a tipping point: This disc-brake road-racing bike is so good, it squashes every one of the complaints and compromises that have dogged its category. So good, the way we look at road-race bikes could be forever changed. So good, there’s little reason to consider buying a road-race bike with rim brakes ever again.
Certainly, disc-equipped road bikes have come a long way from the first models that debuted just a few years ago. At the time, they were impressive first steps, but in all areas except braking, they lagged behind their rim-brake counterparts. Even as they got better, you could still feel that you were on a disc- brake bike: They were at once overbuilt and too soft. The rim-brake road bike was still the benchmark for performance.
But this Tarmac Disc is light, lively, stiff, smooth, quiet, and exceedingly fast. The brakes are phenomenal, the drivetrain nearly perfect. Just saying it’s “laterally stiff and vertically compliant” doesn’t do it justice. It’s really, really stiff in every good way, and it’s also impressively smooth and damped for such an aggressive bike. But what makes it truly special is that it doesn’t ride like other disc-brake road bikes. Instead, it feels like the most well-rounded race bike you’ve ever experienced—that just hap- pens to have disc brakes.
This is partially because we have arrived at another tipping point: This Tarmac Disc was not adapted from a rim-brake predecessor like so many first (and even second) generation disc-brake road frames. It was developed from the start to use disc brakes.
While the frames look similar, there are some differences in carbon layup and structure to accommodate the brakes while maintaining the same handling and stiffness. Disc-equipped bikes have traditionally been less aerodynamic than rim-brake bikes, but in the wind tunnel, the rim and disc Tarmacs are equally aero at all wind angles, says Specialized. Frame stiffness and vertical compliance are almost identical as well, despite the differences in axles (the rim-brake bike uses quick- releases; the disc bike, thru-axles) and where the brakes attach.
The weight is impressive, too. Our test bike landed on the scale at a scant 15.5 pounds. That’s with paint (the black finish is lighter), an electronic drivetrain, hydraulic disc brakes, 50mm- deep clincher wheels, a power meter, thru-axles, aerodynamic tube shapes, and bottle cages.
If you’re a gram counter, yes, the Tarmac with rim brakes is lighter still. But not by much. The disc frame is within a few grams of the rim-brake bike’s (claimed) 8oog frame weight; the disc fork is about 10 grams heavier than the rim-brake fork. With Shimano Dura-Ace Di2, the top-of-the- line S-Works Tarmac Disc weighs only about 300g more than the rim-brake bike. The additional weight comes almost entirely from the shifters, disc rotors, and disc-compatible hubs, says Stew Thompson, Specialized’s road product manager.
Its low weight is likely one rea- son the new S-Works Tarmac Disc is so lively. We found it to be a quick-feeling bike—even more so than previous generations.
But there’s something different about this Tarmac. It’s quick, but it’s not a handful, because the handling is intuitive and predictable. We’d attribute at least part of this sensation to the bike’s supreme ability to absorb bumps and road irregularities, which grants it excellent traction, feedback, and composure when cornering. It’s a tad mind-warping, actually. The Tarmac is reactive and turns quickly, but it’s also very stable feeling.
Of all the tipping points this Tarmac Disc represents, this is the most significant: No longer is the benchmark for road-racing bikes embodied by a rim-brake bike. Right now, the S-Works Tarmac SL6 Disc is the gold standard. From now on, the best road-racing bike in the world will have disc brakes.