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by James Huang
January 20, 2017
Photography by James Huang
Disc brakes and aerodynamic efficiency have traditionally been considered to be mutually exclusive, especially when compared to the latest crop of ultra-integrated rim-brake calipers that sleekly blend into the surrounding structures. Specialized claims the new disc version of its Venge ViAS can go head-to-head with the rim-brake version, however, both in the wind tunnel and on the scale. That may be, but how does it ride on the road? U.S. technical editor James Huang spent the last five months on a mid-range Venge ViAS Expert Disc Ultegra model to find out.
Disc brakes provide improved stopping power and control over rim brakes, but even the latest flat-mount versions are still undeniably blocky — hardly a shape designed with airflow in mind. Nevertheless, Specialized claims that the new Venge ViAS Disc is only slower by “zero to maybe 2 seconds max over 40km.” According to company aerodynamicist Chris Yu, the secret is not so much in what was added, but rather what was taken away.
Removing the standard version’s convoluted rim brake calipers allowed for cleaner, slimmer, and more streamlined forms around the fork crown and seatstays free of cabling and pivot hardware. And according to Specialized, those blocky flat-mount disc calipers are sufficiently sheltered by the surrounding structures so as to make them drag-neutral; the only remaining aerodynamic downsides are the rotors.
The Specialized Venge ViAS Expert Disc Ultegra is the latest incarnation of the company’s aero road machine.
The Shimano hydraulic disc brakes used on this Venge ViAS Disc Expert Ultegra model do add mass relative to the rim brake version, but Specialized has an answer here, too. In addition to having a sleeker form, the company says the new disc variant’s revised carbon lay-up schedule has shaved enough weight to offset that gain.
This latest Venge ViAS frame also wears a nearly identically sculpted form as the standard rim-brake version, with deep cross-sections throughout, a nicely blended fork crown/head tube area, and close-fitting cutouts around both wheels. The same “FACT 11r” carbon-fiber blend as on the flagship S-Works version is used here, too, but with exposed cabling in front of the head tube along with a standard stem instead of the more integrated ViAS model. Both changes likely have some downside in terms of aerodynamics, but the impact for most riders will more likely be in terms of aesthetics. In particular, whereas the ViAS stem profile flows neatly into the head tube on the S-Works model, here there’s an odd-looking concavity that looks disappointingly unfinished.
There’s certainly no questioning the aero intent of the Venge ViAS frame. Many have argued that the addition of disc brakes muddies a bike’s lines, but in this case, they arguably clean them up relative to the rim-brake Venge ViAS.
Other details include a neatly integrated wedge-type binder for the matching deep-section carbon fiber seatpost, 12mm-diameter front and rear DT Swiss thru-axles with repositionable levers, and Specialized’s latest OSBB oversized press-fit bottom bracket shell — a slight variant of the BB30 interface used elsewhere.
While the frame may be shared with the S-Works model (save for the cable routing), the more budget-friendly parts of this Venge ViAS Disc Expert Ultegra model undercuts the flagship by a whopping US$7,000. Featured on the spec sheet is a Shimano Ultegra mechanical drivetrain with an FSA SL-K carbon crankset, Shimano R685 hydraulic brake/shift levers with matching flat-mount calipers and Ice Tech rotors (160mm front, 140mm rear), and 24mm-deep, 20mm-wide DT Swiss R470db aluminum clincher wheels.
Top-end Venge ViAS models use a profiled stem with fully internal wire and housing routing that runs through the stem and into the frame. The mid-range Expert Disc Ultegra model does without either of those features, and suffers aesthetically (and probably aerodynamically) as a result.
The rest of the build kit wears the Specialized logo, including 24mm-wide S-Works Turbo tires, an Aerofly aero-profile carbon handlebar (with 25mm of rise), a Pro SL forged aluminum stem, and a Power Expert saddle with hollow titanium rails.
Total weight was 7.74kg (17.06lb), without pedals or accessories.
Characterizing the performance and ride behavior of a bike is often akin to reading a book: it’s only after reading the pages for yourself that you’re able to fully dissect the plot line. But in the case of the Venge ViAS Disc Expert Ultegra, what you see on the cover really is what you get, and there are few surprises out on the open road.
The Venge ViAS is billed first and foremost as an aerodynamic machine, so as you’d expect, it’s at its best when cruising quickly on smooth tarmac: head down, back flat, pedals spinning furiously, quads firing in metronomic rhythm. Its aggressive geometry promotes an efficient body position with its long reach and low stack, the bulbous chassis feels as rigid as it looks, and the handling is quick and immediate with fast reflexes that reward an attentive rider.
This sort of seatstay-seat tube junction was once only found on time trial bikes, but it’s become increasingly common.
Overall, there’s a certain directness to how the Venge ViAS conducts itself, with minimal filtering between surges at the pedal and changes in speed, or inputs at the bars and changes in direction — in other words, it’s a race bike, through and through.
That directness translates to the bike’s ride quality as well, though, and there’s little give either in the chassis or the wheelset to temper any road imperfections. Some aero machines try to counteract the unyielding nature of those deep-section frame tubes by incorporating some sort of mechanical devices to provide cushioning. Trek’s Madone uses the company’s unique IsoSpeed pivoting seat tube design, for example, while the Felt AR uses a novel, ultrathin seatpost construction with an elastomeric head. Similarly, the Cervelo S3 seeks to accomplish the same goal with pencil-thin seatstays, while Canyon and Scott go with truncated airfoil frame tube shapes that are naturally more prone to fore-aft and vertical flex than full-teardrop tubes.
The head tube sports a pronounced hourglass shape that’s just wide enough in the middle to let the steerer tube pass through.
The Venge, meanwhile, pairs that deep-profile seat tube and down tube with a an aggressively shaped carbon fiber seatpost to match. At more traditional tire inflation pressures (90+psi), the ride is undeniably rough, even with the supple casing construction of the stock S-Works tires. There’s the usual damping associated with carbon fiber, but even with the generous seatpost extension provided by the sloping frame profile, there’s no discernible flex happening when you hit a bump. That chassis harshness doesn’t just affect rider comfort, either. Without the benefit of any built-in give, the bike sometimes skitters nervously through corners, struggling to maintain grip if the road isn’t at least reasonably well paved.
Dropping the inflation pressure down to 75psi helps immensely, but there are practical limits with how low you can go before risking pinch flats on the stock 24mm-wide clincher tires with inner tubes. That said, there’s plenty of room in between the stays and fork crown for higher-volume rubber should you so desire. Depending on where you measure, there’s 40-45mm of clearance on my 52cm sample, meaning you could easily run smooth-treaded 30mm-wide tires with little issue. Paired with 28mm-wide tires and a new-school, ultra-wide aero wheelset like the Enve SES 4.5AR Disc, the Venge ViAS Disc becomes quite the intriguing proposition.
Specialized bucks the trend of truncated trailing edges with sharp tails on the Venge ViAS seat tube and seatpost.
Regardless of tire pressure, the Venge chassis may be stiff and efficient, but it’s also a bit lifeless and dull with minimal road feel and a somewhat robotic personality overall. Riders who seek a proper tool for a specific job probably won’t take any issue with this fact, but those that place a higher priority on a bike’s intangibles like “springiness” and “liveliness” might be disappointed.
I conducted no objective aerodynamic testing during this review, but the Venge certainly looks the part, and independent tests conducted by other outlets — namely, Germany’s Tour Magazine — at least confirm the speediness of the rim-brake Venge. If you take Specialized’s word at face value in terms of how closely the disc version mimics the rim-brake version, this latest Venge certainly stands among very premium company when it comes to aerodynamic efficiency.
In addition to improved braking performance, the switch to disc brakes on the Venge ViAS Disc creates heaps of additional tire clearance. 24mm-wide tires come stock, but there’s 40mm of space, at minimum, in between the stays and fork crown for higher-volume rubber.
Many riders will be just as equally concerned with how well the Venge performs in terms of crosswind stability, though, and I’ll admit to being pleasantly surprised. It was much easier to hold a line in blustery conditions than I had expected, given the generous frame surface area.
Keep in mind that some of that stability comes as a result of the wheels Specialized has specified on this particular build. While the DT Swiss R470db aluminum clinchers ride pretty well and are decently light at 1,640g for the set (actual weight), they’re not the best match for the frame’s primary design goal with their shallow 24mm depth. Specialized says the wheels were chosen so as to help keep the price point reasonable, and in fairness, this Venge comes fairly well equipped for the money. Nevertheless, fitting non-aero wheels to one of the most aerodynamic chassis on the market feels like an odd choice.
The stock 24mm-wide Specialized S-Works clincher tires are fast, supple, and grippy. The DT Swiss R470db wheels to which they’re mounted are a curious choice here as they’re not particularly aerodynamic, but their 20mm internal width puffs the tires up to an actual width of 26mm.
Specialized also provided a supplementary set of its new 32mm-deep Roval Rapide CLX 32 wide-profile carbon clinchers (a separate review of those is pending). I tested the bike with both, and the carbon clinchers’ reduced weight and more streamlined profile made for quite the tangible boost in speed. Granted, it isn’t reasonable to expect such an upgrade to be included without greatly increasing the cost of the complete bike. But other companies selling aero road bikes in this price range still manage to fit less-expensive aero wheels to suit, and it would have been nice to see that here, even if it were to come at the expense of something else on the spec sheet.
The rest of the componentry is straightforward with as-expected results all around.
Rear shift performance from the Shimano Ultegra transmission was as precise and consistent as always, and chain movement up front wasn’t far behind, held back only somewhat by the substitution of an FSA SL-K crankset in place of the matching Shimano one, which offers stiffer and surer-shifting hollow chainrings.
The latest version of Specialized’s OSBB press-fit bottom bracket shell now uses permanently bonded-in aluminum cups, but still with narrow bearing spacing. When paired with a wide-format 30mm-diameter spindle like on the FSA SL-K crankset used here, the extra room is filled in with spacers that only add to the potential for creaking.
Meanwhile, the R685 hydraulic disc brakes provide gobs of power with pinpoint control to match. Kudos to Specialized for specifying a larger 160mm up front to supplement the 140mm rear one, although it would have been nice to see Shimano’s finned Ice Tech rotors for better heat dissipation. Braking was pleasantly quiet at both ends regardless, at least in the dry; wet conditions elicited the usual howl typical of Shimano disc brakes, but similar performance nonetheless.
Much has already been written about Specialized’s novel-looking Power saddle with its curiously clipped-off nose, and there are no new revelations to discuss here. Despite the odd appearances, I found it to be as comfortable as ever, especially while in the drops.
Speaking of which, the S-Works Aerofly carbon aero handlebar was a pleasant place to spend time with its agreeable bend and reasonable wrist clearance. Aero-profile drop handlebars often compromise comfort for better wind tunnel numbers, however, and that trend continues here. The tops of the Aerofly may very well be speedy, but the trailing edge is annoyingly sharp, and the broad surface is sometimes a challenge to grasp even with large-sized hands.
My biggest complaints on the Venge ViAS Disc Expert Ultegra lie not so much with the words on its pages but rather the subtlety and nuances in between the lines — and more specifically, how those details occasionally make themselves known audibly.
Specialized has used its subtle proprietary press-fit bottom bracket concept for many years now, and while this Venge ViAS Disc frame uses the same long-standing “OSBB” tagline, it’s not the same as OSBB frames of yore. Specifically, aluminum cups are now permanently bonded into the carbon shell from the factory, and bearing cartridges alone are then replaced as needed. In effect, it’s now a BB30 shell instead of the PF30 ones used earlier. Either way, those narrowly spaced bearing cartridges support a wide-format 30mm-diameter crankset spindle, with the extra real estate filled in with aluminum spacers. It’s the worst possible combination in terms of creaking potential, and indeed, I did get some intermittent groaning down below.
Unfortunately, the permanently bonded-in aluminum cups make it more difficult (but not impossible) to use a thread-together, wide-format bottom bracket that would do a better job long-term of preventing creaking.
Normally, problematic BB30 and PF30 shells can be remedied by using a bottom bracket made with cups that thread tightly to each other, such as from Enduro, Wheels Manufacturing, and others. However, while Specialized’s latest OSBB treatment uses a common bearing spacing, the bonded-in cups (and, more importantly, their integrated inner flanges) will make it harder to find an aftermarket option that will work. Short of that, should creaking eventually be a serious issue, the most likely fix at that point would be press new bearings in with either green Loctite or two-part epoxy.
I heard some occasional creaking from the seatpost and its wedge-type binder, too. Unlike traditional slotted arrangements, the Venge’s seat tube looks cleaner, but can’t wrap around the post when the bolt is tightened. Instead, tightening the wedge pushes the seatpost harder against the back of the seat tube, relying on the closeness of the fit elsewhere to discourage movement under load (which is the fundamental cause of creaking). In this case, a generous application of friction paste did the trick; fingers crossed it was enough to keep it that way.
Likewise, I’ve generally been a fan of Shimano’s latest hydraulic brake/shift lever shape, but I’ve also noticed over the years that they’re prone to rattling. The ones on my test bike proved no different, and while I’ve figured out various ways to squelch the noise, a proper fix is long overdue.
Specialized claims the move to disc brakes on the Venge ViAS hasn’t come at the expense of weight or aerodynamics relative to the rim-brake version.
Both ends of the frame feature wheel-hugging cutouts, which are now more visible without the rim-brake version’s bulky calipers.
The seatstays join lower on the seat tube so as to reduce frontal area. The small hole in the seat tube provides a visual reference for the minimum seatpost insertion.
The flat-mount disc caliper interface is admirably clean and tidy. Repositionable DT Swiss thru-axles are used at both ends.
Specialized tops the aero seat tube with a similarly profiled carbon fiber seatpost.
Take one look at the Venge ViAS frame, and it’s little surprise that it’s stiff under power. There’s a lot of surface area in play here.
The down tube features a close cutout just behind the front wheel, but it transitions to more of a U-shaped profile as it approaches the bottom bracket shell.
The fork crown flows smoothly into the surrounding structure.
Whereas the rim-brake version of the Venge ViAS has proprietary calipers tucked in behind the fork crown, the area is pleasantly open and clean on the disc-brake version.
It’s a shame these housings are flapping about in the breeze up here, as the head tube area is otherwise quite tidy.
Bigger bottom bracket shells don’t automatically equate to stiffer frames, but the additional cross-sectional area certainly doesn’t hurt.
This brake caliper certainly doesn’t look at all aerodynamic, but Specialized contends that it’s actually the rotors that present a bigger issue in terms of drag.
Specialized specs a 160mm-diameter rotor up front, but a smaller 140mm one out back. The smaller rear rotor helps save a bit of weight, but it also makes sense since the front handles the majority of the braking duties.
The frame is prepped for electronic drivetrains should you decide to make the switch. Laser-etched aluminum water bottle bolts are nice finishing touches.
The wedge-style seatpost binder looks clean and holds tight, but it takes a healthy coating of friction paste to keep the area silent.
Specialized’s frame designers have certainly made full use of the available real estate afforded by the OSBB bottom bracket shell.
Specialized says the built-in rise on the S-Works Aerofly handlebars is more aerodynamically efficient than traditional headset spacers if a higher hand position is needed. That may be, but the aesthetics are definitely polarizing.
The tops of the S-Works Aerofly handlebar aren’t particularly comfortable with their sharp trailing edges and very broad surfaces. The forward angle to the tops does provide plenty of wrist clearance when in the drops, though.
The drops feature a pleasant bend and are quite comfortable.
The FSA SL-K carbon fiber crankset definitely saves weight over a Shimano Ultegra one, but it doesn’t shift quite as well.
The Shimano Ultegra transmission was hard to fault, offering clean, consistent, and precise shifts. We’re guessing Ultegra will soon see the same improvement debuted on the latest Dura-Ace R9100 groupset, too.
The clipped nose of the Specialized Power saddle certainly raised more than a few eyebrows when it first debuted a couple of years ago, but the shape definitely works for most riders willing to give it a try.
Are disc brakes the future for aero road bikes? It certainly seems that way.
Specialized acknowledges the real-world power outputs of its customers, including a wide-range 11-28T cassette and 52/36T chainrings on the Venge ViAS Expert Disc Ultegra.