Tubeless and tubed: Specialized revamps its S-Works Turbo tyre range
Tubeless and tubed: Specialized revamps its S-Works Turbo tyre range
2022 has been a pretty healthy year of wins for both Quick-Step Alpha Vinyl and Bora-Hansgrohe, and along the way, you may have noticed them on some tyres that weren’t in Specialized’s pre-existing catalogue. Our sleuthing from February had us confident that Specialized was looking to correct its marketing misstep concerning tubeless (a dead horse we’re exhausted of flogging), and the company has since released the updated line of tubeless-ready Roval road wheels with an explanation of the issue. Now the accompanying tyres are ready to put Specialized back onto #teamtubeless.
Specialized has announced three new models of S-Works Turbo tyres. There’s the S-Works Turbo RapidAir tubeless tyre specifically made for racing, a tyre that has already racked up a few wins at the Giro and Vuelta. Meanwhile the S-Works Turbo 2BR Tubeless is sure to have the most interest as it’s a performance tubeless offering built for everyday use. And then there are the tubed (clincher) versions of the new S-Works Turbo and lower-cost Pro. And before you Turbo tyre loyalists get anxious, just breathe – the Turbo Cotton clincher will remain in the line-up unchanged.
As expected from the Big S, these new tyres come with a lot of brand-provided hype. However, having spent the past few weeks on the two new tubeless models, it seems that hype may be somewhat justified. And the bigger picture here is that Specialized’s approach to tubeless safety is one we hope becomes the industry norm.
These tyre releases also coincide with the Roval Rapid CL II wheelset being made available for aftermarket purchase.
New compounds for the Turbo range
At the centre of the new Turbo tyres is a wholesale revamp to the rubber that contacts the road – the first update since the introduction of Specialized’s original “Gripton” a decade ago. Now the S-Works Turbo range features a new dual-compound Silica-based rubber tread that’s claimed to be grippier, more cut-resistant, and more durable, while offering lower rolling resistance.
Before bikes, Specialized’s first ever product was a tyre, and the category remains lucrative for the company today. So much so that Specialized runs its tyre research and development facility in Germany (tyres are contract manufactured in Thailand) with easy access to emerging technologies and its sponsored teams.
According to Specialized’s tyre product manager, Oliver Kessel, there have been some big advancements in rubber compounds in recent years. Kessel attributes these developments to the competitive race among those developing electric vehicles. Here, increased vehicle weight, greater motor torque, and a focus on distance efficiency between battery chargers have all led to fresh research in the space.
For Specialized, the compounds in its road tyres follow a path rolled out by its latest mountain bike tyres with a self-defined scale based on rubber rebounds. The gravity-focussed mountain bike tyres (T7 and T9 compounds) offer slow rebound and tacky rubber that’s designed to grip onto wet rocks like a snail, while the road rubber (T2 and T5 compounds) prioritises a fast rebound that absorbs less energy.
These proprietary rubber compounds came about through testing both the rebound and the elastic hysteresis losses. The rebound test is a rather simple one that involves a weighted pendulum: the less the pendulum bounces back, the more energy is absorbed, and therefore the slower the rubber will be. Meanwhile, the elastic hysteresis test focuses on heat build-up within the material during compression. The more heat a rubber takes on for a given load, the more energy it has absorbed, and therefore, the slower it would be if used in a tyre.
Those tests were combined with lab-based cut and abrasion tests to find rubber compounds capable of balancing low rolling resistance with real-world requirements. The result is arguably not revolutionary, with a more springy and faster “T2” compound in the centre of the tread, with a slower rebounding “T5” compound on the shoulders of the tyre where traction is most desired.
However, in chatting to Kessel, his constant references to trade-offs and real-world usage stood out most. Specialized’s new tyres are indeed faster than before, but won’t likely be the very fastest in drum-based tests (something Specialized also has access to in-house).
Perhaps the best example of this is the fact the tread is carried far around the tyre’s casing; further than is usually seen. It’s a design decision that Kessel openly admits adds weight and hurts the rolling resistance figure. So why do it?
Rims are only getting wider, and increasing the tread width helps ensure the contact patch with the ground is solid. Wider rims or not, criterium or road racers will be familiar with wearing the sidewalls of certain tyres when leaning hard through fast corners, and the wider tread needs no explanation there. Meanwhile, that rubber gives additional puncture resistance to the otherwise exposed sidewall.
Speaking of tread, Specialized has kept the Turbo’s synonymous micro dot pattern on the shoulders, intended to offer more consistent grip across imperfect road conditions, allowing that raised grip to more easily build heat for improved traction. The pattern has been tweaked, but the claimed benefit remains the same.
Tubeless safety
Specialized had previously spent plenty of time and energy promoting the future of road tubeless before it hit a snag with its first-gen Rapide and Alpinist wheels. Now they’re back singing the praises of tubeless, with rather impressive safety requirements to go along with it.
The two new tubeless-ready tyres, the S-Works Turbo RapidAir and the S-Works Turbo 2BR, fully comply with the recently revised ETRTO standards related to hookless (aka Tubeless Straight Side or TSS) and hooked (aka Tubeless Crochet TC) rims. More importantly, the tyres go well beyond the required 110% safety margin related to maximum pressure – a safety issue we discussed with Josh Poertner (owner of Silca) on the Nerd Alert podcast.
Specialized’s internal tests require that the point of tyre blow-off occurs at no less than 200% of the maximum recommended pressure. In the case of hookless rims and the usual maximum recommended pressure of 72.5 psi, Specialized is confident its tyres will stay on the rim if inflated to double this (although the maximum recommended pressure remains at 72.5 psi). Meanwhile, on hooked rims, such as Roval’s road wheels, the tested burst pressure is closer to a whopping 260 psi, which is a fair way above the 110 psi max recommended pressure.
All of these results are theoretically worst-case scenarios, with the testing conducted on specially made rims sized to be the smallest dimensions allowed by the ETRTO standards.
At the opposite end you may notice that even the widest Turbo tubeless tyre has a minimum recommended pressure of 65 psi – a figure that’s a fair bit higher than what Silca and Zipp’s pressure calculators may spit out. Kessel states that these figures are based on a number of factors, including impact testing where lower pressures leave the rim vulnerable to square edge impacts (such as a pothole). In gravel and mountain biking it’s common to run pressures far lower than the recommended minimum, and while it seems Specialized can’t legally recommend as much for its road tyres, it’s surely the path many will take here.
Like what Continental has done recently, the American company has also taken further steps to add some needed nuance around its fitment and usage recommendations. Specialized goes against the ETRTO standards and states that its smaller 26 mm tubeless tyre isn’t recommended for use with 25 mm internal width rims. Meanwhile, Roval tubeless road wheels now come with varying pressure guidelines based on the width of tyre used. It may be more information for a user, but it’s exactly the sort of use-specific nuance we’re keen to see more of in the road tubeless space.
Kessel also spoke to CyclingTips about improvements in the manufacturing process and tooling, which provide benefits in air retention (and reduced weight). The sidewall of the tyres now features a far smoother and more consistent covering of rubber with manufacturing venting greatly reduced straight from the mould (so fewer of those little rubber spikes that poke out from the sides of the tyre). As a side benefit, the tyre has a shimmer that looks higher-end, too.
It’s worth noting that both of these new tyres are tubeless-ready, meaning liquid sealant is recommended to ensure great air retention. Specialized recommends its own high-pressure-specific RapidAir sealant, but in reality, any sealant designed to handle higher pressures will do just fine.
S-Works Turbo RapidAir
Like the original RapidAir, the new and premium-priced S-Works Turbo RapidAir (US$90 / £65 / AU$140) is intended to be Specialized’s racing-focussed tyre. The general goal remains unchanged from the original: to create a tyre as fast and light as the Turbo Cotton clincher but with improved grip and flat protection.
The general construction is unchanged from the patent-pending approach of the previous model, with a somewhat minimal two plys of a 120 tpi (threads per inch) nylon casing that meets an ultra-strong tubeless bead. Specialized offers this model in a single 700 x 26 mm size, which measures an actual 27 mm on the 21 mm-width Roval Rapide and Alpinist rims found on Specialized’s own bikes and as used by its pro riders. And surprise surprise, it just not-so-coincidentally happens to be the aerodynamically optimised tyre size for the Rapide’s front rim profile.
According to Kessel, the new RapidAir is one watt faster than the previous version (measured at 40 km/h, 100 psi tyre pressure, 45 kg load for a single wheel) and is a close efficiency match with the Continental GP5000 S TR. It also matches the rolling resistance of the company’s Turbo Cotton clincher tyres run with a latex tube. And it’s now a few grams lighter, with my samples weighing 238 and 240 grams.
Specialized sought to benchmark the rate of air loss against a tubular, with the RapidAir (and 2BR model) losing about 15 psi in 24 hours while the tubular (built on a latex tube) would lose that pressure over just six hours.
Our experience with the original RapidAirs was that of a grippy and super fast tyre, but one quite prone to cuts. Specialized claims a 12% improvement against punctures in the new tyre from the combination of its new rubber compounds and revised breaker beneath the tread.
Meanwhile, Specialized makes no small claims related to durability, boasting an approximate 1,000 km increase with an average lifespan of 4,000 and 3,500 kms, front and rear, respectively (based on its in-house abrasion tests and correlated to real-world use).
I’ve only had a few rides on the new RapidAir, so I’ll keep my opinions brief. Fitment was snug, especially so on Roval’s own Rapide wheels that had me reaching for a tyre lever after my thumbs alone had failed. However, it’s less of a fight than a Continental GP5000 TR, and I was able to get the RapidAir on a new Shimano 105 carbon rim (review to come) without tyre levers. Regardless of the wheel it was mounted onto, I was able to inflate the RapidAir with nothing more than a regular floor pump.
I’ve yet to do any practical comparative testing with this new tyre. Still, general riding provides a wonderfully smooth and rather effortless feel that you’d hope of from a premium and race-focussed tyre. However, what stood out to me most is just how secure in traction this tyre is, and there was never a sense or sound of it not staying stuck. In this sense, it’s a tyre that feels better than most when committing to a corner.
S-Works Turbo 2BR
If the RapidAir is made for racing, then the Turbo 2BR (US$80 / £55-£60 / AU$125) is Specialized’s answer to an everyday performance tyre that’s still good for pinning on a number. This tubeless model doesn’t stray too far from the RapidAir, but adds more to the durability and puncture protection metrics at a small trade-in rolling resistance and weight.
Compared to the RapidAir, the 2BR gains a third layer of 120 tpi casing and a tweak to the puncture-resistant belt. As a result, the tread section is approximately a millimetre thicker (measured at 3.23 mm), and the weight and rolling resistance are said to be more comparable with where the old RapidAir sat – about a watt slower and 10 g heavier. My 28 mm tan-walled samples weighed 271 and 274 grams, while Specialized quotes 260 grams for the 26 mm version.
That more everyday purpose also comes with a bunch more options in terms of available sizes, and yes, colours. Specialized will offer the new Turbo 2BR in 26, 28, and 30 mm sizes, with a black or tan-wall sidewall. Like the RapidAir, the smallest 26 mm size can only be used on rims 23 mm wide or less, while the wider options are good for up to 25 mm width rims. And what about a 32 mm tyre size? Well, nothing yet, but it sure sounds like something is in the works.
Where the RapidAir is claimed to last 4,000 and 3,500 km of use, the 2BR ups those figures to 6,000 and 5,000 km, front and rear, respectively. According to Kessel, Specialized’s in-house testing shows the 2BR to outlast the Continental GP5000 S TR. Two small dots in the tread serve as a wear indicator to help you prove Specialized right or wrong.
I’ve been testing this tyre’s 28 mm tan wall version over the past few weeks, and early impressions are positive. My only criticism is that this tyre was marginally harder to install on Roval’s Rapide CL when compared to the RapidAir, but that perhaps says more about the slightly oversized Rovals than it does about the tyres.
Otherwise, it’s all positive. There are no signs of unwanted tread nicks or cuts. As expected the grip closely matches the feel of the RapidAir, but that extra casing thickness does result in a vaguely less supple feeling. I’m a fan of the Continental GP5000 S TR, and it seems Specialized has created a comparable all-rounder.
S-Works Turbo (clincher) and Pro
Specialized is well aware that not everybody wants the sealant upkeep and increased user complexity of road tubeless. For those riders, the new S-Works Turbo (US$70 / £45 / AU$100) is the tube-specific equivalent of the S-Works Turbo 2BR. And yes, it’s easier to install.
This clincher tyre gains the same new dual compound tread and puncture breaker as the tubeless models (which can also be run with tubes, if you wish). In the smallest 24 mm size, this tyre is claimed to weigh just 200 g a piece while offering an 8% increase in puncture protection over the old version. This one isn’t quite as quick-rolling as the company’s Turbo Cotton clincher, but is intended to offer improved grip, durability, and puncture resistance.
Meanwhile, there’s also a more affordable Pro version (US$TBC / £TBC / AU$85) of the clincher tyre. The Pro version cuts cost with a sturdier 60 tpi casing and uses the slower-but-grippier T5 rubber compound across the whole tread. We expect wear rates to be better with the S-Works version, given the T5 is a softer compound.
For those seeking a tubed version of the RapidAir racing tyre, that would be the Turbo Cotton that remains in the range unchanged.
Time will tell
Early impressions point to Specialized producing a competitive product in the road tubeless space. Only time and community experience will tell whether the tyres meet the claims.
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