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First look review: Mavic Cosmic Ultimate UST wheelset

15 Jun 2018

Mavic’s Cosmic Ultimate UST wheel brings tubeless clincher tyres to the brand's flagship tubular WorldTour wheel

Cyclist Rating: 
An aerodynamic, light and stiff World Tour class wheel finally in a tubeless-ready clincher version
Pricey, spokes can't be tensioned for wheel truing

Conjure an image of a wheel in the Tour de France in any period in the last 25 years, and you may struggle to get the iconic yellow logo of Mavic out of your mind. The brand has been an iconic part of World Tour racing.

For many years, though, the brand’s top wheel has been largely confined to pro cycling. Today we’ve been given the first glimpses of a clincher, tubeless ready, version of the historically tubular-only Cosmic Ultimate.

With carbon spokes and a fully carbon hub shell, the Cosmic Ultimate UST looks every bit the pro level wheel. While it looks like a reworking of the tubular version of the wheel, there have been substantial changes to the wheel.

Old meets new

The Cosmic Ultimate first appeared in 2006, when it was a vision of the future. It had the same deep section carbon and carbon spokes, but was strictly tubular. That was partly down to Mavic policy.

Mavic believed that carbon clinchers were too compromised in braking terms, meaning that when Mavic eventually released a carbon clincher wheel in 2013, it had an internal aluminium rim to dissipate heat and maintain a consistent brake track.

Over the last few years, Mavic has developed considerably in terms of carbon technology, and with the last range of UST carbon wheels had done away with the aluminium internal rim.

Resin and carbon technology has come on substantially, though, and Mavic has also used an innovative means of dissipating heat more quickly - the rim’s foam core. ‘With a hollow rim you have different heat dissipation than with foam,’ says Maxime Brunand.

Profile comparison - tubular Cosmic Ultimate and Cosmic Ultimate UST

The product of that was Mavic’s Cosmic Pro Carbon SL, which came with tubeless tyres ready mounted, but now sits directly below the Cosmic Ultimate, which proves lighter, more aerodynamic and stiffer. But there’s also been considerable improvements to braking performance too.

One intelligent measure to improve braking has been the treatment of the carbon at the brake track. Using what Mavic calls iTgMax technology, the resin which covers the brake track has been shaved off by laser, revealing a rougher pure carbon brake track beneath which better conducts heat and increases friction for the brake pads.


The other challenge of Mavic new carbon wheel range has been the introduction of Tubeless compatibility. ‘The next challenge was to introduce our UST system, which we did last year.’

Mavic’s Cosmic Ultimate has no spoke holes and so has an airtight rim bed, meaning there’s no need for tubeless tape. The tyre have also been reworked to improve Mavic’s holistic offering.

Now being developed in collaboration with Hutchinson tyres, the new Yksion Pro UST uses a completely new compound that offers the greatest balance between rolling efficiency and grip.

‘We actually designed this compound in-house,’ explained Brunard. ‘It is not just a racing tyre, but a strong tyre for training too.’

‘It’s UST ready which means it’s low weight,’ Brunard continues. ‘And it’s protected against most puncture with only 30g of sealant for 25mm tyres. We have it in 25mm and 28mm widths, but have optimised this wheel with 25mm tyres.’

Better, faster, stronger

Mavic’s R2R carbon-fibre spokes stretch a single line of fibres from one end of the rim to the other, laced through the Ultimate’s carbon front and rear hub shells.

That, unsuprisingly makes for a highly stiff wheelset, although there is a hefty disadvantage as the spokes cannot be tensioned by hand. That means that after, say, a crash they will need to be returned to Mavic or replaced.

On the bright side, the weight has also been carefully preserved with the carbon spokes, and the entire wheelset comes in at only 1310 grams. The tyres add an additional 290g. 

While Mavic has not traditionally been associated with the highly aerodynamic brands such as Zipp and ENVE, its engineers claim impressive class-leading aerodynamics for the wheel.

In comparison with industry-leading aerodynamic wheels, Mavic claims that the Cosmic Ultimate comes out on top within a certain range of yaw (-20° to 20° to be specific). See comparison table below:

‘Some wheels are slightly better at lower yaw angles,’ says Brunard, ‘but there are very few differences for our competitors.’ 

Part of that is down to the newly widened tube shape compared to the tubular Cosmic Ultimate and part of it is down to the aerodynamics on offer from the spokes. ‘You can see that the cross-section of the spoke is not just a flat spoke but an ellipse which does a lot for aerodynamics,’ says Brunard.

First impressions

Mavic’s supply of the wheels is currently very tight, but we were able to get a five hour ride on the Cosmic Ultimates in Corsica, at the Explore Corsica cyclo-sportive, through bouts of torrential rain.

The first impression from the wheels is of a stark and rigid responsiveness. The wheels pick up at the mildest input of power and deliver a highly efficient acceleration – aided by the low overall weight.

In fact, I found the wheels almost added an extra sense of stiffness through the entire frame. That helped to deliver good acceleration and also a sense of handling accuracy.

The aerodynamics are not easy to perceive, but the wheels did seem to cruise along happily above 40kmh, holding speed very well.

Users of the older generations of Cosmic Carbone will be most relieved that there’s none of the side-gust force which were common with those wheels, as the new rim shape handles these winds far better.

Braking was a standout success, as even in the stormy rain showers I rode through, the brakes were at times a little soft but always began to bite quickly enough to avoid any momentary scares.

On drier descents, the brakes were consistent and dependable. I found myself grabbing the brakes later and later into corners, and did smell burnt rubber on a few occasions. The carbon of the rim braking surface remained undamaged, though.

We’ll need a long-term test set to draw more in-depth conclusions, however the early impressions are very good, with these wheels exceeding anything we’ve seen from Mavic so far. 


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