2016 Mavic Cosmic and Ksyrium Pro Carbon SL Clincher road bike wheels

Photo: Mavic

Last summer, when they launched their all-new hubs and carbon tubular wheels, Mavic started down the road of new, wider Ksyrium and Cosmic clinchers. At the time, though, the prototypes were headed toward an alloy rim bed insert. That design had been their go-to for years, allowing them the look of a full carbon rim but with the security of an alloy bead hook and bed to better resist tire pressure and heat buildup. And, we rode it and it was headed for production.

But, thanks to recent hires and advancing resin technology, they were able to switch gears and develop their first full carbon rims. So, not only are they getting wider, but they’re using an entirely new construction method that builds the bead hook and rim bed as a single piece…with NO need to machine the hook. Fibers remain intact, new resins give them the requisite heat tolerance and a laser machining finish provides amazing stopping power.

As Mavic’s president Bernard Millaud explained at the start of our presentation, “You will now see the second phase of Mavic’s carbon development…”


What does a good carbon clincher need? For Mavic, the answers are the ability to handle the mixed stresses of the tire’s air pressure pushing out, brake pads pushing in and ground impacts pushing down.

Technically, they say carbon is really good at handling pressures in one direction at a time, so getting it to handle all three is a challenge. Then, you add a fourth: temperature. Braking quickly builds up an excessive amount of heat, up to 200ºC (392ºF). They say most resins have a Tg (melting temperature) well below that number.

They serviced about 100 wheels during the 2015 Etape de Tour (a ~140km fondo), with 52 of them being failures and 38 were carbon clinchers that had delaminated or otherwise destroyed themselves.


The rims also have to meet safety standards, which is more than just impact testing. It’s also how the tire fits into the bead hooks and rests on the sidewall, and that is the larger challenge. Molding the proper curves and bead hooks are very difficult, which is why nearly every rim manufacturer overbuilds the sidewall then machines away the inside to create a bead hook. The problem with this method is that it breaks the fibers and creates potential weak spots. This is why Mavic has thus far used alloy inserts inside the channel, avoiding the need to machine the fibers. Those designs also helped dissipate heat, but it wasn’t without its own challenges.

Bonding the alloy rim bed into place was the original plan, but they were getting too many rejects off the production line. The process was just too difficult, and when they wanted to start making wheels in different widths and shapes, it was easier to just do it in full carbon.

All of those challenges went into a development wish list. The result? Carbon Clincher 2.0, in which they’ve found a better way to manage the heat and create the perfect bead channel shape straight out of the mold.


The rim bed’s shape is made from multiple layers to create a one-piece contoured section. The lower body of the rim is laid up separately, then the two pieces are molded together. The rim is full carbon without any post-production machining, shaping or finishing. Only the excess resin is sanded off. They do this by building up the rim bed and bead hook as a single piece, letting that section cure, then wrapping the lower section over it in the final mold. This lets them use the same rim bed section for both the Ksyrium and Cosmic Pro Carbon SL wheels. To form the bead hook, they use a soft plastic mold inside it during the heat molding process, then it’s simply pulled out. The thicker part of the hook (A) is a cord of wound carbon about a pencil lead’s thickness. The other thick section between the upper and lower bodies (B) is a slightly thicker cord. These allow the carbon to be built up to the necessary thicknesses quickly and easily, without requiring a ton of overwrap.


The result is an inner rim bed meets all ISO and ETRTO safety standards right out of the mold and is perfectly smooth. The inside of the rim is formed by using an ultra-thin bladder, which is inflated during the molding process to push the fibers against the metal molds from the inside out. This compacts the fibers and squeezes out excess resin. Mavic started using bladder molding for the Ksyrium Pro Carbon SL tubular launched last summer. Other models still wrap the carbon around a foam core, but one of Mavic’s carbon engineers told us as the rims get wider, the bladder becomes a lighter weight option. And it is light, barely registering in my hand when I held one…which is good because it’s left behind inside the rim as part of the molding process.


The inside width is 17mm for both the Cosmic (26mm external, 40mm deep) and Ksyrium (25mm external, 26mm deep). For comparison, the CC40 had a 13mm internal width, and the Ksyrium was already 17mm internal, but only 22mm external. Before you think “oh, but 17mm is so narrow, Mavic just doesn’t get it”, we let them explain:

First, there are few real standards when it comes to road wheel’s bead hook shape, tire and rim interface sizing, etc. (and even fewer if any for road tubeless, but that’s whole ‘nother story). Mavic’s brand goal is to be an “unbeatable combination of performance and reliability”. That last bit is why they are deliberate with new product development instead of pushing ahead with ultra wide rims and road tubeless offerings. They could do it, but they’re not confident it’s the right solution (which can be read as a hint that they’re working on their own solutions, just at a pace that doesn’t necessarily suit the rest of us). So, these are not tubeless ready.

So, the 17mm internal width is what they need to get the right tire shape to optimize ride quality, handling and rolling resistance. The wider 25mm (Ksyrium) and 26mm (Cosmic) external widths then optimize aerodynamics around that tire size, too. It’s also about safety:

A 25mm tire is the smallest you can use, and it’s the size the rim was designed for, but technically you could safely run up to a 50mm tire. So, running a 28 or 30 is no problem. They do not recommend using a tire narrower than 25mm because if a 23mm tire or smaller is on there and suddenly loses air pressure, it runs the risk of coming off the rim. So kids, bigger tires are better here, m’kay? Fortunately, the 25mm has quickly become all but standard in the pro peloton, and extremely popular among cyclists everywhere.

The extra width comes at no weight penalty, either. The rims are light, coming in at just 400g for the 26mm deep Ksyrium, and 450g for the 40mm Cosmic. Mavic’s wheel product manager says weight savings over the early prototypes with the alloy internal rim bed is only about 5g, because anything they removed in alloy was replaced in carbon.


Regarding aerodynamics, the rim shapes uses the now common rounded aerodynamic profile that’s slightly wider just below the brake track, and these numbers are with a 25mm tire. The drag chart above shows the new Cosmic Pro Carbon SL against it’s predecessor and several competing rims of similar depths. Only one averaged slightly lower drag, but all are close. To be honest, in this day and age, most aero wheels are so close to each other in average drag performance that what you’re looking for is something without drastic swings in drag as the yaw angle changes. A flatter line means a more stable wheel in gusts. The short of it is this: Mavic’s new wheels are aero and, in that regard, perform on par with the competition.


So, if it’s not aerodynamics that sets them apart, what does? Well, there’s the safety aspects of a stronger, one-piece molded rim. And there’s the braking performance, which is nothing short of remarkable.

Mavic developed a proprietary resin mix and curing process to withstand temps up to 200ºC, which they say is at the extreme end of what might be seen in real world conditions. The brake track consistency is also checked, and their molding process produces nearly zero surface variations. That means no grabby spots. Then they use a laser machining treatment on the braking surface to remove the outer resin coating and expose the fibers. This gives it enhanced friction in both wet and dry conditions, particularly when used with their own special blend of SwissStop yellow pads.

They tested with the SwissStop Black Prince pads, too, and performance was slightly better, but those pads were too aggressive for their rims. The laser machining leaves the fibers exposed, and they found the Black Prince pads were causing a little too much wear for their liking. So, it’s a custom yellow pad formulation for production.


Mavic tested competing carbon clinchers’ braking performance in both dry and wet conditions, using the stock pads that are provided with each brand’s wheels. In dry conditions, each performed within a ~5m range. It’s the wet weather testing that showed massive differences, and if these hold up in real world riding, Mavic may have just solved the achilles’ heel of carbon rim braking, providing a more consistent, predictable stop regardless of weather.

Once it was proven in the lab, real world testing is done by riding down the Mont Ventoux and dragging the brakes continuously down the middle section of the mountain, which gives them a 10km run averaging about 10º decline. Heat buildup was measured using heat sensitive decals placed inside the rim bed.

We didn’t get a chance to test them in the rain, but I can say that their dry braking performance is astoundingly good. Whatever hype Mavic dishes out in this regard, the wheels live up to it.

The other part of improved braking performance is heat management, which we’ve already covered and is handled by their new iTgMax resin (i = integral, as in full carbon).


Or, you could just go with disc brakes.


Both will be available with the Center Lock hubs, which also have the new “star ratchet” style toothed rings of the new Instant Drive 360 hubs.



The only difference in the disc brake rims is that they don’t receive the laser machining process, and the decals run right up to the edge.

Other hub details include:

  • Same hubs that were introduced last summer on their All Road and tubular versions of the Ksyrium Carbon SL and Cosmic Carbon SL Tubulars.
  • 40 teeth for a quick 9º engagement, which is a big improvement over the 17º two-pawl system it replaced.
  • 12/15/QR front convertible
  • 142×12/QR rear convertible
  • All parts included, and switching them is a tool free affair. They’ll have a converter kit for 12×135, too. They’ll fit in the Specialized SCS system, too, if you replace the SCS derailleur hanger with the standard version available through Specialized.




The Cosmic is Mavic’s mid-depth “fast and light” wheelset. Retail pricing is:

  • Cosmic Pro Carbon SL C Disc (€2,090 / $2,399.90 / £1,550)
  • Cosmic Pro Carbon SL C (€1,990 / $2,199.90 / £1,450)


The Cosmic gets 18 stainless steel spokes in the front, 24 in the rear. Those spokes have a new elliptical shape that improves aerodynamics, letting it ride just as fast as most 50mm deep wheels but at a lighter weight. They spent a lot of time testing and developing them, then they had to work closely with their supplier to get the manufacturing process right.

mavic-cosmic-pro-carbon-sl-clincher-road-wheels12 mavic-cosmic-pro-carbon-sl-clincher-road-wheels10


The complete wheelset weighs in at just 1,450g, and it comes with 700×25 Yksion Pro tires (front and rear specific) that weigh in at a claimed 210g apiece. Wheels come with custom yellow SwissStop carbon brake pads, skewers, bearing adjustment tool and rim tape. Disc brake wheels also include axle end caps for QR and thru axles.




The Ksyrium is their shallower “endurance” line that’s intended to be the lightest offering. The wheels ship with the same goodies as the Ksyriums and retail for:

  • Ksyrium Pro Carbon SL C Disc (€1,990 / $2,199.90 / £1,450)
  • Ksyrium Pro Carbon SL C (€1,990 / $2,199.90 / £1,450)


The Ksyrium spokes are their flat alloy spokes, which are still using a NACA aero shape and are a little bit lighter weight. Wheelset weight is claimed at just 1,390g, something I appreciated on the thousands of feet of climbing we did during the launch in Nice, France.


The hubs are available with Shimano/SRAM, Campagnolo and SRAM XD-R freehub bodies. (Note: XD-R is simply a 1.7mm wider version of the XD Driver Body for mountain bikes, with the extra width to match up with current 11-speed road freehubs so it’ll fit inside bike frames correctly. Yes, we’re thinking that it opens up room for a 12th cog, too…)

For now, they don’t have 650B or Lefty versions to fit the Cannondale Slate. They’re not saying never, but it’s not on the immediate road map.

Stay tuned for first ride impressions, coming soon.




They’re launching a free worldwide “Riding is Believing” test program through dealers, and you’ll be able to find a participating dealer and reserve a pair online at Mavic.com. The dealer will prep the wheels for you to pick up, and then you both have the opportunity to send feedback to Mavic. Starts April 15 in France and UK, then the rest of the world May 1. At launch, they’re looking to have up to 1,500 dealers on board with the Cosmic Carbon SL, then expand reach and models shortly thereafter.

Mavic Care Plus is the new extended warranty program that replaces their old plan at the end of August. MCP adds a year at no charge, extending the original warranty to three years. Plus, their carbon wheels are now included in the crash replacement program that lets you nab a replacement set for 40% off MSRP if they’re damaged outside of normal warranty issues. Lastly, warrantied wheels will now be able to be dropped off and replacements picked up where ever you want – your home, office or favorite Mavic dealer – in countries where Mavic is sold directly.



  1. Veganpotter on

    I don’t really care what excuses they come up with for a 17mm internal width rim. 19+ provides a significantly better ride than a 17 which is barely competitive any longer. What’s the point? I could see this if it were optimized for a 21mm tire but it’s not. Narrow tires don’t roll as well but 23s tend to be more aero than 25s, even on wide rims. Run skinny up front and fatter out back. 23s fit fine on modern rims that are 19+ internal… even 22s are doable

    • typevertigo on

      It’s Mavic simply conforming to ETRTO rim width regulations.

      As per the same regulations, a rim with 19 mm internal width is a little too wide to fit a 25 mm tire. It can be done, sure, but there’s a bigger chance of the tire unseating itself. The narrowest tire the ETRTO recommend used on a 19 mm internal width rim is 28 mm.

      Currently, 28 mm tires aren’t really in vogue in the pro peloton outside of the cobbled Classics events. 25 mm tires are much more common. That seems to be their main motivation for the 17 mm internal width.

    • gattonero1974 on

      With rim brakes there is one thing that people doesn’t seem to get: tyre clearance in respect to the brake caliper and the frame/forks.
      This is a MAJOR safety issue.
      Wider rims tend to alter the shape of a tyre, making it bigger, thus leaving less clearance with what’s around (brake calipers, frame, forks). When seelling figures are 7-digits figures (or more) one cannot afford the chance to have lawsuits from people that went over the bars due to a leaf stuck in between their wheel and the forks.
      In a nutshell: is still too early to push the road tyres so wide, frames and forks are following this trend but not all the road brakes can fit wide tyres. Better safe than sorry.

  2. Antoine on

    That’s cool and all but seriously mavic no tubeless ? i mean you almost “invented” bike clincher and released bike tubeless long before anyone. Clincher is no good. what would you do once you flat without a “service course”. Whereas with some stan one has almost no more flats.

  3. Corky on

    Yeah, you can bang on about your highly technical construction of your rims but until you start producing tubeless….I ain’t listening. #leftbehindagain

  4. Chad Moore - Mavic on

    Hi everyone, Chad from Mavic. Thank you for these questions and comments.

    Regarding the width of the rims – a 17mm internal width is becoming common for many road wheels – carbon and alloy. Look at Zipp, Stan’s and Enve and you will see the similar specs. We believe that the 17mm internal width is an optimal solution for the road and then you’ll find wider rim specs in on our Allroad wheel-tyre systems (19mm internal).

    Regarding the internal rim width in relation to tyre width. What I hope can be clear is that we’ve made a choice to follow the ISO and ETRTO norms that are established, annually, to recommend the appropriate combinations that ensure consumer safety. Based on these norms, the maximum internal rim width for a 25mm tyre, which the majority of consumers are riding (depending on where you live), is 17mm. Based on the established norms, there is an high risk of failure if you run a 25mm tyre on a rim with an internal width greater than 17mm. Now, take a 19mm (internal width) rim as the next example. The minimum tyre width that is recommended, based on the norms, is 28mm. So, if you run a 25mm tyre on a rim with a 19mm (internal width) rim, you are outside of the norms and again, at risk for failure.

    In the end, our goal is to offer the best solution for consumers in terms of performance and reliability. By following these norms we are also providing the safest solution for rim/tyre combination.

    Regarding tubeless, as Tyler mentioned, it is another story all together. I will say that our Allroad wheel-tyre system is tubeless ready – so you can see that where (we feel) it makes the most sense, we are making that option available. You can be assured that if we don’t believe tubeless is the best solution that we are working on what we think IS the best solution.

    I hope this is helpful – always happy to discuss.

    • Luiggi on

      “But, thanks to recent hires and advancing resin technology…” so you guys are using ENVE’s patentes. Way to take credit for something you just bought off the shelf!

      • Chad Moore - Mavic on

        Hi Luiggi – in fact, the “recent hires” refer to Jean-Christophe Minni who is the head of our Composites Department. He has been at Mavic for a few years now so I assure you we have our own patents and technology in these wheels.

      • Mick on

        @Luiggi, really (?) …the ink is barely dry from the sale of Enve to Amer Sports …business does not move that fast, nor does product development. These wheels have more than likely been in development for a yr or more.

    • TheKaiser on

      Hi Chad, thanks for taking the time to answer questions here!

      I understand Mavic’s stance on sticking to “ISO and ETRTO norms” as a kind of guarantee of acceptable performance, however when this discussion of rim to tire width ratios comes up there always seems to be this kind of blind faith that ISO and ETRTO norms offer optimal performance too. Also there are often a lot of vague assertions about how deviating from their rim/tire width standards can create an unsafe situation. Even in this article, there is reference to how running a 23mm or narrower tire on these rims could cause it to come off the rim during a sudden loss of air, but no explanation of why that would be. My experience is that the ability to keep a tire on the rim while flat has more to do with the tightness of the bead interface, not the carcass width.

      I think anyone with any understanding of the wheel and tire system can see that if you go too extreme in either direction (ie. 4.0″ fatbike tire on 15mm internal rim or a 21mm tire on a 35mm internal rim), but it seems like Mavic is restricting themselves to a smaller than needed portion of the usable spectrum, that may not even be placed in the middle of the sweet spot. The adherence to ISO and ETRTO norms is more the sort of things I would expect people to do in the litigation heavy USA, simply to prevent accusations of making an unsafe product rather than optimal performance, but in this crazy inversion we have Stan’s reinventing rim/tire fit in the USA and a French company being worried about deviating from (possibly sub-optimal from a performance perspective) standards.

      Additionally, why the willingness to go tubeless on the gravel road offerings, but not for pure pavement? There may be more benefits for gravel riders, but some people’s “road” rides, include some pretty crappy roads and so it would be nice to have the option, and if you can make a safe rim for gravel use, surely it could be done for the road too. If it’s because tubeless use could cause rim failure at your target weight then it’s best to just be honest about that, rather than saying vague corporate speak like “we don’t think it is an optimal solution” or “it could create an unsafe condition”, because those same accusations could certainly be directed toward the standard clinchers too.

      Thanks again.

      • Chad Moore - Mavic on

        Thanks for the input TheKaiser

        Regarding the ETRTO and ISO norms:
        They have performed tests on all of the current options available for rim/tyre combinations. The reason we stick to them is that they are the only ones doing the work to establish the recommendations AND that they have seen the failures when going outside the norms. Their testing represents scenarios that are achievable in cycling, so in order to be sure we are offering a safe solution to consumers we feel it is important to work within those guidelines. As those change, you can bet that our technologies will as well.

        Regarding tubeless:
        When we say that we don’t think it is an “optimal solution” it is in reference to both the user experience and design and development limitations. As I am sure you know, tubeless is a chore to setup and getting a flat on a ride and having to get the tyre off to put a tube in can cause the most calm person to throw their bike in a ditch. Of course I’m being dramatic, but again…we don’t want to fully endorse the idea of putting people in that situation. In addition, there are design limitations when it comes to tyre beads that I won’t go into detail on – mostly because I’m not an engineer and I trust our R+D team. However, there are real limitations to what you can do with tubeless tyres in a high pressure situation (such as on a pure road system) that impact the usability and ride quality. That’s partly why on our tubeless ready 30mm tyre, the max PSI is 80.

        I’ll leave it at this for now and hope that you all have a chance to experience these new wheels. Even if they are not tubeless we are quite proud of what we’ve accomplished both in braking and in providing what we truly believe to be the safest and most reliable carbon clincher option on the market to date.

        Thanks all for your comments and support, we appreciate the input.

          • Chad Moore - Mavic on

            Hi Rriedy – since the new wheels are full carbon there is no alloy in order to accomplish the FORE drilling. This technology is only available on the alloy wheels and the previous version of our carbon clincher – the CC40 Elite. Thanks!

  5. Chad Moore - Mavic on

    Hi Luiggi – in fact, the “recent hires” refer to Jean-Christophe Minni who is the head of our Composites Department. He has been at Mavic for a few years now so I assure you we have our own patents and technology in these wheels.

  6. Jdog on

    No tubeless – no sale. All the Enve road wheels will be tubeless within a year. Wake up jokers. Tubes are a liability.

    • Jason on

      Jdog. Please do not try to speak for everyone saying tubeless is the way to go. I am an avid road rider and commuter. I would not want tubeless on my steed.

  7. Ojos Azules on


    Did you know that Mavic development/testing cycle for products is 3-year minimum ?
    If Mavic intend to use some Enve patents or technology for their products, they won’t be out before 2020.

  8. Dirty Sanchez on

    Chad Moore, thank you for the explanation’s. Good luck with all of the arm chair engineers chiming in. You’re a brave man responding to the trolls. How dare you have your own ideas on where tubeless is the best solution and where it’s maybe not? And Bikerumor, I can’t believe you still report on new offerings….Aren’t there any high tensile steel frames to report on?

  9. Tom on

    Looks like really good stuff. Priced a little stiffly, but not surprising.

    Chad Moore – thanks for the thoughtful responses. I was VERY interested to read that there is such a thing as too narrow of a rim for a particular tire width. I for one am hoping that the knowledge tradeoffs go both ways between Mavic and Enve, since both undoubtedly have their strong and weak areas.

  10. Vandertran on

    What’s up with all the hate? 17mm internal is just fine vs 19mm. I doubt you can tell the difference between 1mm on each side of the rim.

    Tubeless road is a messy niche market, in my experience, high tire pressures, low volume, and sealant can cause more headaches than it’s worth. Makes more sense for gravel/off road with bigger tires/lower pressures as Chad mentioned.

    Wheel weights look reasonable and in line with the rest of the market and pricing seems reasonable as well vs ENVE, Zipp, etc.

    Durability is hard to quantify on a new product, but if the marketing hype is true, it would set these wheels apart from the crowd.

    Chapeau to Mavic and Chad for discussing and providing another alternative to the already crowded carbon clincher market.

  11. Joe C on

    Wow. Does Chad have the toughest job in the world, or what? I guess I’m lucky my 25s are staying on my 5 year old Belgium’s, since they’re too wide and violating some standard that is meaningless in the real world.

  12. lorn on

    1. jeez, everyone’s an expert.
    2. who honestly thinks tubeless is the best option for road wheels? saying that it’s tubeless or nothing is totally absurd, imo.

    • mac on

      2. Me. Lots of crap on the shoulders of the roads I ride on. Had many punctures due to little pieces of wire and glass. Went tubeless one year ago and haven’t had another flat. Once more roadies get over themselves and drop this badge of honor thing they cultivate about changing tubes, they’ll find that it’s awesome.

    • CXisFun on

      I too doubted road tubeless, then I went through one particularly rough week of riding over the winter this year with 13 flats in 6 days. In January I went tubeless and haven’t had another since (knock on wood).

  13. ano on

    To have a competitive wheel/rim in todays’ marketplace it really does need to tick all the boxes. No exceptions. Launching a high-end wheel in 2016 and omitting tubeless compatibility is a massive oversight and I have a feeling people will vote with their wallets.

  14. Want on

    @Luiggi Really is amazing that the parent company bought Enve two weeks ago and they already have a new product out of it. Fantastic turn around!

  15. Johnny Cash on

    Chad Moore , you’re in a no win situation on here !! I would forgo the pleasant responses and just let your products do the talking for themselves…. Most if not all of these hacks wouldn’t even be able to true their wheels let alone build and design one! It’s Mavic we are talking about here , I am sure they are capable of building anything! Market hype and me too just isn’t their thing right now maybe they want to innovate in their own way

    • Mr. De Facto on

      I work at a shop too. I would hope you recommend the best solution to your customers. And you know for fact tubeless is NOT always the best solution for a racer, one day a week rider and just about everybody. I’m going to sell the sh*t out of these wheels, thanks MAVIC!

  16. Billy joe on

    Too little too late. Yawn.

    Also the whole internal width thing is bologna. I’ve run 23c on my 21 internal rims with 0 problems.

    • Chad Moore - Mavic on

      Hi Billy joe – you make an interesting statement on which I would like to offer some input/feedback. I’ve discussed it with our product manager, engineers and one of the heads of the ETRTO and ISO norm committee in charge of establishing these safety norms.

      We have no argument that you, or possibly anyone else, may not have had an issue with running a rim/tyre combination that is outside the established safety norms. However, these safety norms exist because there are documented failures, based on the testing of real world scenarios, when using certain combinations. Even if it is only (hypothetically) a 1/1000 chance that a failure would occur, a company like Mavic simply cannot, and will not, put that one consumer at risk.

      With the setup you mention, you are far beyond the safety norms and we truly hope that you never end up having a failure like the ones we’ve seen. The reason we are so adamant about these safety norms is, again, that we will not put any of our consumers at risk by making our own interpretation(s) of the tests and the results.

      • tri4life on

        Chad, I find this whole discussion about safety very interesting. Honnestly I like your new wheels and I find that 17mm internal width is not a big deal, it’s clearly much better than previous wheels like Cosmic carbon 40 CC or CXR 60 which were very very narrow. I may be tempted to ride the GP4000S 700×23 on these new wheels as it is known to be the most aerodynamic tire (+ it is a very good tire other than for its aero properties) but I get that ETRTO 17mm internal width = 25mm minimum tire section. The one thing I wonder though is : what is Amer going to do with ENVE rims in term of safety ? I know you work for MAVIC, not for ENVE, but I think the AMER SPORTS group probably has the same philosophy when it comes to safety and not having custommers take any risk even if it’s only a “1/1000 chance that a failure would occur”, then my 6.7 have a front rim that is a hair over 18mm internal width and recommended for 23mm tires (confirmed to be OPTIMIZED FOR 23mm tires to be exact) ! New 4.5 have a front 4 that is 18.5mm wide inside, recommended tire size is 25mm, again outside of the rules. New 7.8 carbon clincher tubeless ready are even wider at 19mm (also 25mm recommended) ! So again I understand you work for MAVIC, not ENVE, but if the same safety rules apply to all the group’s companies, does that mean you need to redesign all ENVE road rims (or allow people to ride 700×28 minimum on these wheels) to bring them to the ETRTO / ISO standards ? Again, really like these new Cosmic Pro carbon clincher, so congrats on these and hopefully you can answer my safety question as I’m both an Enve and Mavic wheels owner.

        • Chad Moore - Mavic on

          Excellent comments and questions @triflife. Enve, even before the acquisition by Amer Sports, was (and still are) part of the “working group” for ISO revision. Also of note -Trek, Specialized, DT Swiss, Shimano, Continental and Sram/Zipp are all involved. Together, we will evolve the safety norms so that everyone can commit to them and to the highest level of consumer safety and performance.

          That said, at Mavic, we’re also committed to following the existing safety norms that have been established based on the current testing. Based on these norms, it’s true that if you are running a setup that is outside the norms, you are at risk. With a 17mm internal rim width you should run (at minimum) a 25mm tyre. With a 19mm internal width, you should run (at minimum) a 28mm tyre.

          There is one other conversation to be had – aerodynamics. Our goal was to provide the best possible rim shape not just for compliance with the safety norms, but also for aerodynamics. On the Cosmic Pro Carbon SL C, which includes the recommended 25mm tyre, we designed an external rim width of 26mm. If you compare that to the rim width of our competitors you’ll notice that the external widths are very close, but the internal widths are quite different. In order to achieve an optimal external rim width, many of our competitors have widened the entire wheel…including the internal rim width. The problem with this method is that (as we’ve already established) when you increase the internal rim width you begin to limit your choice of tyre width if you would like to stay within the safety norms. In order to offer a wheel-tyre system that allows you to have the best combination of speed, performance, reliability and safety we designed the wheel around an internal width of 17mm in order to allow the ability to safely run a 25mm tyre. If you’re looking for something that is aero, and you have a wheel with a 19mm internal width AND if you want to be within the safety norms, you should run a 28mm tyre. And the facts show that a 28mm tyre is not the most aero option. So, to be within the norms you should manage the relationship between the choices you need to make – desired external rim width + tyre + internal rim width + compliance with safety norms. As you can see, there are a lot of topics to consider. Our first priority is safety.

          In the end, the decision is up to the individual. From our side, since we deliver all of our wheels with their tyres, we are already making a choice that can’t be outside of the norm. This choice is to have a very clear statement on what we want out of our new carbon clinchers for our customers. A performance system that is fast, light, reliable and safe. We truly believe we have ticked all of those boxes based on our clear focus and decisions on what we feel is the best solution for cyclists. This wheel is a shining example of how the wheel-tyre system approach to wheel design can be truly beneficial for the end result.

  17. mac on

    Enve was super late to the tubeless party as well. Mavic should have recognized that mistake instead of following their lead.

  18. Tdj on

    How irresponsible for Mavic to design a wheel with safety as a priority. I think it is hilarious that some of you wont buy these based on 2mm on internal width.
    These look like a fast, stiff and safe wheelset. I would be happy to own a set.

    • Kernel Flickitov on

      Mavic deemed 1st gen R-Sys safe and they blew up all over the place. Tell me, how do you quantify a “safe” wheel set by looking at a photo?

    • Chad Moore - Mavic on

      Totally up to you JBiz. The Moots/Butter CX team in Colorado ran the tubular version of the Ksyrium Pro Carbon SL Disc to great success last year. Either one would be great!

  19. Durianrider on

    What about the crappy cheap freehub bodies that are sloppy out of the box and wear out and can slip over time excessively?

    Why not just copy DT Swiss freehub design?

    Mavic make great looking wheels but the freehubs are absolute rubbish no matter how much you spend.

    • greg on

      “Both will be available with the Center Lock hubs, which also have the new “star ratchet” style toothed rings of the new Instant Drive 360 hubs.”

  20. Dominic Bruys Porter on

    I’m going to throw my hat in with the Anti-tubeless-for-the-road crowd here. Even the Hutchisons only seat first time about 50%of the time. For my money, pinchflat protection is in tubulars, but that’s another topic entirely.

    17mm is actually the inner dimension on the Grand Bois rims, the same company so obsessed with comfortably riding tyres they practically invented 650b.

    Also, why is nobody praising the fact that they finally made a wheelset with actual aerodynamic spokes?

    I’d still really like an aftermarket rim with Exalith for CX but i aint holding my breath.

    • Padrote on

      hutchinson tires are a poor representation of a tubeless tire. which is odd considering how long they have been doing it.

  21. David on

    Using an 8 year old Reynolds DV46C profile that has been out of production for over 3 years. I wonder why? They are correct about the internal width when it comes to retaining ideal tire shape. If you want a more ride comfort you use a wider tire, not a “narrow” tire stretched out on a wide internal channel rim.

  22. B on

    I, for one , will not be riding these wheels as well. Simply because I still have my original set of cosmics from the 90’s running true. D*mn you Mavic and your function over form shenanigans!

  23. Pete on

    I realise that the Ksyrium Carbon pro is not an aero wheel … however, how does the drag profile of it compare with the Cosmic? Would be interesting if the Ksyrium data was added to the above drag graph

  24. Bruce on


    What can you tell us about brake pad wear? All of the reviews applaud the outstanding braking performance, and a few reviews mention faster-than-average brake pad wear. That makes sense, given the softer yellow pads with the new braking surface treatment.

    I completely understand that there are a huge number of variables involved, so there is no single answer to brake pad wear. I am just trying to get a SENSE for how often I’ll be changing brake pads versus my current setup (Ksyrium K10s with SwissStop BXPs). Twice as often?


  25. Leo Aguirre Richards on

    I got a pair of cosmic carbon pro sl about 6 months ago from my local bike shop “Serious Cycling” and I like the wheels very much and ride the Santa Monica Mountains often. I recently descended Tuna Canyon for the first time and I MELTED my rear wheel. I am 6′ 4″ and 180 lbs and have been descending without any issues but this canyon is very long and steep and I had to drag the brakes more than I like to and it seems that I was a bit heavy on the rear brake. I read articles like this explaining the wonders of the brake features and improvements made in the heat management and tests conducted at iconic descents. I cannot imagine that Tuna Canyon could be more challenging on the brakes than the iconic European mountains described in multiple articles. The main difference may have been the rider …. In any case, I took the wheel to Serious Cycling, they contacted Mavic and they replaced the wheel to which I am grateful and I am not planning on descending that Canyon again with these wheels.


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