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by James Huang
June 21, 2017
Photography by Mavic
Hutchinson and Shimano brought the concept of tubeless road clinchers to the mass market almost ten years ago, and the list of tire and wheel/rim manufacturers who have followed suit has grown considerably since then. Mavic is hardly averse to the idea of tubeless bicycle tires – it introduced the first mountain bike tubeless system all the way back in 1999 – but save for a single model released just two years ago, Mavic has stubbornly stuck by conventional inner tubes for the road.
Mavic’s position has always been that it wasn’t willing to offer a system it didn’t feel was fully refined for consumer use — and in fairness, there’s some merit to that position. But now, after a long, long, wait, Mavic has debuted a more user-friendly tubeless road clincher wheel-and-tire system across its entire 16-model range, with more on the way.
Mavic has long been aware of the potential advantages that tubeless clincher road setups can provide. When done well, they often roll faster and allow for lower operating pressures, are more resistant to punctures, can provide better security after a puncture, and can be lighter than tubed setups. But according to Mavic, existing tubeless road systems have been too difficult to set up at home or in the shop, even more difficult to service on the road, and offer an inconsistent quality of fit between different wheel, rim, and tire manufacturers that can be frustrating at best, and potentially dangerous at worst.
“At that time, we weren’t satisfied with the user experience,” said Mavic product line manager Maxime Brunand. “It was super hard to assemble the tires because you had to use carbon (fiber) beads, and the rims and tires were pretty narrow. So we said we didn’t want to back it up. We wanted to improve the user experience. It was always difficult.”
Unlike Hutchinson’s original tubeless road tires, which used carbon fiber beads that were prone to breaking if mishandled, Mavic’s new Road UST tires use conventional aramid beads.
Mavic’s new Road UST (Universal System Tubeless) design, on the other hand, supposedly retains all the benefits of current tubeless systems, but with none of the usual hassles.
Mavic has developed Road UST in-house with some additional assistance from fellow French company Hutchinson, who helped developed the rubber compound and will manufacture compatible road tires under the Mavic label. Mavic promises that the tires can be easily mounted and removed, and that the beads can be seated with a standard floor pump or even roadside with a mini-pump. In the event of a catastrophic loss in pressure — say, from a sliced sidewall — Mavic claims its Road UST system can be safely ridden while flat without fear of the tire peeling off of the rim.
Mavic has long resisted entering the road tubeless fray, but is now jumping in with a new concept called Road UST.
Even with the recommended 30mL of latex-based sealant, Mavic claims a weight savings of 40g per pair relative to a comparable tube-type setup, while casing construction and rubber compounds have also been crafted to offer “the best balance of grip and low rolling resistance.” Best of all, Mavic says ultra-tight tolerances for the rim and tire dimensions will make that the case for every one of its new Road UST wheel-and-tire setups.
“It’s easy, it’s safe, and it’s fast,” said Brunand. “It’s the only standard in road tubeless.”
While I can’t comment firsthand on how well Mavic’s new tubeless system stays together on the road when flat, I can attest to the ease-of-service claims. During a demonstration at the company’s headquarters in Annecy, France, I had no problems mounting a Road UST tire onto its matching rims by hand — as in, no tire levers required. Afterward, I seated the tire using nothing more than an everyday, low-volume floor pump, and both beads fully seated at around 60psi without the dramatic (and sometimes startling) “pop!” that often goes with tubeless setups.
More impressively, I was able to slowly peel the deflated tire back off the rim afterward, again with no levers required.
Mavic’s new Road UST design will find its way into the company’s entire road range, from entry-level aluminum all the way up to premium full-carbon aero clinchers.
Whereas Mavic only dipped its toe into the tubeless road waters in 2015 with the Ksyrium Allroad, the company is now so confident in its Road UST system that it will be offered in 16 wheelsets for 2018, covering the gamut from entry-level aluminum models to premium full-carbon models for both rim brakes and disc brakes — a price range of roughly US$450-1900 / €450-1900, with availability spanning between now and September.
In a first for the industry, all of those wheelsets will be sold exclusively with Road UST tires pre-mounted for tubeless use; all that’s needed is to inject the included sealant, inflate, and ride.
Save for some Europe-only models, all of the wheels and rims will measure at least 17mm between the bead hooks, with some puffing up to as much as 22mm; most will be a healthy 19mm — a far cry from the 13mm internal widths Mavic offered on some wheels even just two years ago. There will also be compatible standalone rims, such as the redesigned Open Pro that debuted earlier this year.
Mavic is also offering Road UST on standalone rims for custom builds, such as the new Open Pro. Photo: James Huang.
A cursory inspection of the rim profiles Mavic is using for its new Road UST system will reveal nothing particularly extraordinary. There’s a semi-circular channel down the middle of the rim, conventional hooked edges, and raised lips to lock the beads in place. But according to Mavic, it’s the precise dimensions that make the system truly user-friendly and consistently safe.
Mavic says the central channel’s depth and radius were chosen so as to not only provide a sufficiently deep well for expletive-free tire installation, but also to produce a reliable initial seal for easy inflation and seating. Those raised lips and modest hooks firmly lock the tire beads in place, but not so aggressively that they can’t be removed roadside.
While the general layout of Mavic’s Road UST rim profile doesn’t break any new ground, it’s the precise dimensions that supposedly lend the system its impressive ease of use and security.
The key, says Mavic, is the very precise dimensions dictated for both the rims and tires, as well as unusually tight dimensional tolerances for all of the key components — more stringent than what Hutchinson uses for its own tires currently, and with less variance than what Mavic had previously deemed allowable for its own wheels and tires.
For example, Mavic says it has historically held its conventional road rim diameter tolerances to 621.95mm +/-0.5mm, but Road UST-compatible models will now vary by only +/-0.35mm; tires are being held to 619.6mm +/-0.2mm. As compared to pre-UST rims, the total variance in rim diameter thus drops a scant 0.3mm, from 1mm down to just 0.7mm. That may sound insignificant, but keep in mind that that small change in rim diameter yields a much bigger difference in rim circumference, and when coupled with the variations in tire bead diameter, can mean the difference between a secure fit and a loose one if any of the components are allowed to stray outside of those parameters.
Those tightly held dimensions apply not only to rim and tire bead diameter, but also how much the tire beads can stretch under load — something Mavic says no one is consistently measuring at all, to the point where the company had to develop and build its own test fixture. All Mavic Road UST tire beads will be made of conventional aramid fiber instead of carbon fiber, too, meaning they’ll be less likely to break if tire levers are used.
Mavic developed its own test fixture to measure not just tire bead diameter, but also how much tire beads stretch under load — a critical component to guaranteeing a proper and consistent fit between tubeless rims and tires. Photo: James Huang.
Keen-eyed readers will note that Mavic’s stated rim diameters are fully compliant with existing European Tyre and Rim Technical Organisation (ETRTO) standards, unlike some tubeless-compatible rim and wheel manufacturers that intentionally go slightly oversized for a tighter fit. According to Mavic, those ETRTO guidelines are soon set to be revised with more detailed information on how tire widths should be matched to rim widths, as well as maximum recommended pressures for specific combinations, and Road UST will comply with those as well.
“The system is completely redesigned to improve the user experience and guarantee safety in all conditions while maintaining the benefits of the technology, like low rolling resistance, good comfort, and good ride quality,” said Brunand. “It’s the only reliable road tubeless system that is easy to use and 100% safe.”
“Ease of use and safety are like grip and rolling efficiency; it’s very difficult to reconcile both,” he continued. “If it’s easy to use, that means the rim is small and the tire is big or stretchable, but that’s unsafe. That’s why the user experience today is more toward the safe side of things because it’s hard to mount.”
Even if you take all of Mavic’s claims at face value, one can’t help but wonder why it took Mavic so long to release its own tubeless system. After all, Mavic — in cooperation with another French company, Michelin — was already heavily invested in its own tubeless system in 2008, to the point where prototype setups were already being tested by some of its professional riders at various high-profile races.
According to Mavic head tire engineer Jeremy Queffelec, the problem was pressure — not consumer pressure to bring a system to market, but rather air pressure.
“Pressure is the key,” he said, “and higher pressure is a big problem.”
Essentially, the core issue was that the very high pressures and small air volumes that were ubiquitous 10 years ago produced so much internal force that it was challenging to safely hold a tubeless system together.
Ironically, what has finally allowed Mavic to embrace tubeless wholeheartedly on the road was the recent move from 23mm tires and 15mm (internal width) rims to the substantially wider setups that Mavic initially resisted. The associated lower operating pressures and higher volumes not only reduced the forces working to literally blow tubeless road wheels and tires apart, but also provided more room inside the rim to maneuver the tire around during installation and removal.
Mavic has been decidedly tentative when it comes to tubeless road wheels and tires, only dipping its toe into the waters two years ago with the original Ksyrium Allroad model. However, new developments in rims and tires, not to mention changing consumer preferences in rim and tire sizes, have changed the landscape.
“As long as we were using narrow tires and narrow rims, it wasn’t so easy,” explained Brunand. “But now it’s become much more acceptable to ride [wider tires] at lower pressure.”
In addition, Mavic was only proficient in one half of the wheel-and-tire puzzle 10 years ago. But today, the company possesses much more experience and investment on the tire side, including dedicated tire engineers and rubber chemists whose resumes include years at Hutchinson and Michelin.
In typical fashion for Mavic, an expansive bank of tests also slowed down the process. More than 50 prototypes of a single tire model were produced during development, varying everything from bead diameter and size, to rubber compounds, casing construction, and tread designs using dedicated machines in-house as well as field testing — an exhaustive, but necessary, process, according to head test engineer Esteban Deronzier.
Mavic will hold the Road UST rim dimensions close to its chest for now, reserving the design for its own wheels, rims, and tires for the first year. After that, however, Mavic says it will allow any and all companies to access and mimic its rim bed dimensions — all in the hopes of improving tubeless road tires’ ease-of-use for more riders.
That scenario is the same as what Mavic proposed when it first launched the original UST design for mountain bikes, back in 1999. Many companies did subsequently adopt the patented rim and tire dimensions, and some, like WTB, even today still adhere to those original UST guidelines. It wasn’t long, however, before non-compliant designs emerged to challenge — and eventually, outsell — what was initially intended to become an industry-wide benchmark for tubeless performance and safety.
Mavic’s new system certainly seems like it could legitimately be the long-awaited holy grail of tubeless road setups, but there’s no way to predict with certainty if it will maintain that position once fully released into the marketplace. Innovation never rests, after all, and invariably, there’s always another brand that believes they can do it better.
Road UST also won’t be easy to incorporate into another wheel or tire company’s product range as it would not only require wholesale redesigns of all compatible components, but would also require that those companies hold their products to the same ultra-stringent dimensional tolerances as Mavic — all of which costs a lot of money.
There’s even the question of certification. Will Mavic allow compliant non-Mavic products to use the Road UST label and logo? Who will be responsible for certification and testing? And who will pay for it?
Mavic instituted a certification program for its mountain bike UST standard back in 1999, and many other companies signed on at the time. That cohesion has faltered in the years since, however, and it remains to be seen how things will go with Road UST.
The prospect of a tubeless system that offers all of the current designs’ benefits in a format that’s much easier to use is invariably appealing, and consumers stand to benefit even more from the concept of universal, industry-wide acceptance of known standards and dimensions.
Whether that actually happens remains to be seen, but Mavic’s new Road UST system seems very promising regardless. One can only hope.