Specialized S-Works Tarmac Disc review

Disc brakes or no disc brakes? That is the question. For Specialized it’s a more important question than for most, because it has committed totally to the move towards disc brakes, claiming that it might eventually phase out its rim brake bikes altogether.

‘The Tarmac has always been a pure-bred race bike,’ says Specialized’s Chris Riekert. ‘But I think when we launched the original Tarmac Disc two years ago [see review on page 2], the disc bike was seen as a club enthusiast’s bike because you couldn’t race it.’

Since then, however, the rules have changed – both literally and figuratively – and the bike now seems to be gaining traction with pro cyclists.

Zdenek Stybar and Elia Viviani, both of Quick-Step Floors, have been competing on the Tarmac Disc this year, and Specialized has the stats to back up the pro endorsement.

It claims the disc version boasts the exact same overall aerodynamics as the rim brake version, which itself is as fast as the previous generation of Specialized’s aerodynamic Venge.

The frame also comes in at an impressive weight of 800g in a size 56cm – which is within 50g of the rim brake version.

If the addition of discs costs nothing in terms of weight, stiffness or aerodynamics – while offering improved braking quality – does that make the Tarmac SL6 Disc the perfect offering?

The rim brake version was certainly a bike that made an impression. At the recent Cyclist Track Day series (where visitors got to try out top-end bikes from a large number of the big brands) it was one of the most popular bikes thanks to its smooth ride, lightning acceleration and assured handling. 

Same but different

For me, the S-Works Tarmac Disc feels strikingly similar to its rim brake counterpart. The geometry is identical (on my size 56cm, at least – some smaller sizes vary marginally) and Specialized’s tradition of engineering disc frames around short chainstays means the rear is just as compact and punchy.

With the more powerful connection of a thru-axle the rear feels even stiffer at times, without suffering in terms of comfort in the way that some overbuilt disc brake frames can.

The wheels, tyres and finishing kit are all developed by Specialized and have an almost symbiotic relationship. The tyres and wheels mix grip, stiffness and comfort perfectly, and the crankset incorportes a power meter that adds just 15g to a normal S-Works carbon crankset.

Getting the power meter working was simple – once I’d worked out to peel off the plastic battery covers. The only hurdle was that the left and right sides needed to be paired using Specialized’s custom app. Many manufacturers would do that in advance, but the app was slick enough.

Once paired, the data was accurate and in-depth, and included the desirable left-right balance reading. I swapped between reading from Garmin Vector 3 pedals and the S-Works cranks regularly, and the wattage was consistent. The watts also came easily.

Partly thanks to its impressive aerodynamics, the bike lured me up to high speeds and then held me there. On long, flat roads I’d look at my bike computer and see 40kmh, and yet it always felt quite effortless. The watts seemed to be high, but the ride was so smooth and efficient that I was able
to hurt myself without even realising it.

When not engaged in subconscious masochism, I found the Tarmac Disc a joy. It mixed a natural smoothness with a healthy rumble that assured me I was moving quickly, all while feeling thoroughly connected to the road.

It combined the feel of a finely crafted steel bike with the stiffness and responsiveness of a carbon aero racer. But much of that could be said of the rim brake version. The question remains, do discs add anything? 

Braking with tradition

I’m generally sceptical of disc brakes on road bikes. Too often the trade-off of more weight, less comfort and extra cash isn’t worth it for slightly better braking performance. With the S-Works Tarmac Disc, that doesn’t seem to be the case.

It may be expensive, but it’s not that much pricier than the rim brake version, which doesn’t include the power meter. Also, the weight is perfectly acceptable at 6.83kg. What discs add to the overall package is something that does really matter, though, because the S-Works Tarmac Disc was built to descend.

The handling is exceptional. It feels planted and assured, while the accuracy and power of braking bestows huge confidence. I found myself taking on sharp corners at speed just for fun.

With the discs, I could control my entry speed all the better, as well as knowing that if I fluffed a line I could still bring the bike safely to a stop instead of binning it in a verge.

On descents it was just as sharp as the Pinarello Dogma F10, but with far less of the stiff ride quality, and I found myself dropping riders who would previously be distancing me on every hairpin.

There is some room for improvement, though. Specialized hasn’t expanded the tyre clearance much over the rim brake version, which can also accept 30mm tyres. Also, the wheel rims are carbon and lightweight, but no lighter than the rim brake version, and I suspect they are cut from the same mould.

Then there’s the pricetag. At £3,250 just for the frame, and over £9,000 for this build, it will be out of reach for the majority of riders, and it will be a year or so before we see a more affordable ‘Pro’ level version of the bike. But I can forgive all of that.

I was asked a few times whether the Tarmac Disc is the best bike I’ve ridden. It’s a question I get asked many times, and normally I steer clear of answering – all bikes are different, and people have very different tastes.

But I can’t shake this feeling that this really is as good as it currently gets. It feels so fast, so nimble, so versatile and yet does it all with a sense of grace and smoothness.

So the answer is, yes, I think it may well be.

Verdict: The S-Works Tarmac disc proves that when carefully integrated, disc brakes can improve an already excellent bike. Specialized's flagship endurance racer is pretty much as good as it gets

Spec

Specialized S-Works Tarmac Disc 2016 review  

The Specialized S-Works Tarmac is a past winner of all three Grand Tours, and now it's had the disc brake treatment

Stu Bowers

To say the Tarmac has had a pretty good run of it would be something of an understatement. First introduced to Specialized’s range in 2003, it has been a stalwart of the pro peloton in each of its various iterations ever since.

It’s one of very few bikes that can lay claim to having been ridden to victory in all three Grand Tours, plus the cobbled Classics.

Of course, all of those winning bikes were set up with calliper brakes, but Specialized is keen to prove that its disc brake version is good enough to be used at pro level too.

So it is perhaps ironic that on one of the first days I took the 2016 disc brake version of the Tarmac out for a ride, the UCI decided to ban disc brakes in its races. 

During this year’s Paris-Roubaix, Movistar rider Francisco Ventoso was involved in a crash where he sustained a deep gash on his leg. Ventoso said it was from a disc rotor on another rider’s bike, and in the resulting furore the UCI rather hastily took the step of banning disc brake use in the pro peloton altogether.

This immediately led to other events, such as the Etape du Tour sportive, following suit and suddenly the bike industry, which has invested heavily in disc brakes in recent years, found itself with a worrying problem.

Since then, there have been suggestions that Ventoso’s gash was actually caused by a chainring, leading to the possibility that the UCI will reverse its ban and we’ll all be back where we started. We’ll have to wait and see.

Stop start

While the future of disc brakes in top-level races is still uncertain, that’s no reason for the everyday rider to delay a decision on switching to discs (unless you’ve got a place booked at the Etape du Tour). And the Tarmac would be a good first place to look.

It conceals the fact that it’s equipped with disc brakes rather well, in so much as they don’t seem to stand out and are certainly not as visually jarring as on some bikes.

The callipers are the new Shimano flat-mount standard and the 140mm rotors keep the whole set-up about as unobtrusive as possible. It also helps that your eyes are distracted by the bike’s incredible paintjob.

Specialized terms it ‘Gloss Blue Tint Flake’, which equates to a seemingly bottomless, glitter-infused blue that resembles a star-studded night sky if you glance down at the top tube as it catches the light. As always, though, a fancy façade is not what we’re here to discuss. It’s the bones beneath the skin that really count.

It didn’t take many kilometres on the Tarmac Disc before I started to appreciate its qualities. It’s light-footed and quick to respond in punchy accelerations, which are traits I’ve found to be somewhat subdued in other disc brake bikes I’ve tested.

Specialized’s engineers have clearly found ways to maintain a level of performance that is remarkably on par with its calliper-braked brethren, and the weight isn’t far off either.

At the heart of that, Specialized UK’s William Watt tells me, is a completely redesigned rear end, created in close collaboration with its in-house wheel brand, Roval. 

Usually chainstay length is governed by the groupset manufacturers, who specify the optimal distance required for the chain to shift and operate correctly in relation to the spacing of the rear end of the bike.

The wider rear end spacing required for disc brakes (135mm instead of 130mm) means the minimum chainstay length must be increased from the standard 405mm to 420mm.

Whereas the rest of the industry appears to have simply accepted this and dutifully followed, Specialized has set about creating a rear wheel and frame system to alleviate the need for extending the chainstays. 

The right side dropout is offset by 2.5mm, and the freehub on the wheel has moved inboard by 2.5mm. This keeps the back end tight, and is no doubt responsible for the nippy feel of this bike both off the mark and when climbing. Plus it keeps the overall wheelbase shorter and this lends itself towards a more responsive ride. 

In short, it feels every bit a race bike, and the best disc-equipped road bike I’ve tested to date. It’s hard to identify where compromises have been made to accommodate the discs – unless, that is, you are the kind of rider who doesn’t want to be stuck with one wheel brand.

No choice

Yes, here comes the caveat: the changes Specialized has made to the rear end means you really have no option but to use the specially made Roval Rapide CLX 40 wheels (at the rear, at least).

This restriction may cause some people to snub the bike, especially since Roval has not had the best reputation for its wheels in the past. Feasibly, using any rear wheel is possible, but it would be a faff to do so, and you’d be compromising the benefits of the design if you did.

But before you accuse Specialized of craftily locking you into using its own in-house wheel brand, the good news is that the wheels performed really rather well. This new disc-specific 40mm Rapide CLX wheelset felt great at speed and didn’t seem overly buffeted about by crosswinds either, suggesting Specialized has made good use of its own wind-tunnel.

Ceramic Speed bearings as standard shows there has been no corner-cutting to keep costs down, as is often the case when in-house brands are specced. 

light-footed and quick to respond in punchy accelerations

I wouldn’t go so far as to suggest the Tarmac Disc offers a comfy ride. This bike is all about the sensation of speed and feeling 100% connected to the road beneath you, which it achieves admirably but means there is a fair bit of vibration coming back through your body at times. 

The only feature that lets this bike down (quite literally) is its rubber. I set a new personal best of five punctures on a single 150km ride on the Tarmac, which doesn’t say much for Specialized’s Turbo 320TPI 700x24c tyres, despite its claim of incorporating ‘Black Belt’ puncture protection. That’s one black belt that doesn’t put up much of a fight. 

Fortunately, switching to different tyres is a simple and relatively affordable fix, and I can’t let them overshadow what is overall a fantastic bike.

Spec