Mavic Cosmic Carbone 40C Carbon Clincher Road Bike Wheels Review
The carbon/aluminum hydrid rim.

They aren’t first to the carbon clincher market, but Mavic believes they have solved the heat issue that plagues the segment.

By mixing the best properties of aluminum, carbon and resin, the French wheel maker says they have finally been able to create a carbon clincher that meets their standard. As usual there is a lot of talk about special resins and proprietary technologies, but as always, the proof is in the riding. We got to take a pair for a few days before they needed to head out to Sea Otter for some initial testing. Read on to find out our first impressions…


Mavic Cosmic Carbone 40C Carbon Clincher Road Bike Wheels Review
Rolling along at high speed.

Carbon does a lot of things well, but the resin that holds it together has one crucial flaw- heat dissipation. Every manufacturer has had to deal with this problem, and each touts their own way of solving it. Mavic has come to the table with a mix of what has become industry standard procedure and their own new methods.

First, like many others, they have a proprietary resin treatment, called TgMAX, that they claim dissipates heat better than the competition. These claims are all but impossible to substantiate. It’s what’s under the carbon where Mavic departs from most others. Mavic uses an aluminum tire bed and bead hooks, called the spine, as the core. The carbon is then affixed over that core using more proprietary technology. Mavic PR man Zack Vestal did say that the process is chemical and purportedly strengthens over time. This combination of aluminum, carbon and TgMAX is claimed to provide heat dissipation properties that others can’t match.

Additionally, the entire rim is structural, which should enhance overall stiffness. Vestal also pointed out that the aluminum core provides better tire fitment, holds air pressure better and resists pulsing.

Of course a wheel is more than just the rim. The 40 C is meant to be a one wheel solution. With that in mind, the rim is a middle of the road 40mm deep with a slightly blunted shape.  Mavic keeps it narrow at 19mm. The hubs are the same carbon/aluminum ones found on high end models. The steel spokes, 20 front and rear, are laced radially except the 2-crossed rear drive side. Like all carbon rimmed wheels, special brake pads are needed, in this case they’re classic yellow SwissStop pads.

So what does all of this weigh? Surprisingly, the front is 670g and the rear comes in at 875g for a total of 1545g. The competitor most referenced by Mavic, the Zipp 303, comes in 70g lighter.


Mavic Cosmic Carbone 40C Carbon Clincher Road Bike Wheels Review
A quick break from the twisty descent.

All of this sounds great, but the big question as always is does it work?  Unfortunately, between the spring snow and these wheels needing make their way to Sea Otter, I only had four rides on them, so my review was limited. We are hoping to get a set for long term test, so the following is just a start:

I threw the 40 C’s on a demo bike that was equipped with 105 level brakes, so my stopping power was already slightly compromised. Not willing to lay it all out on the first ride, I chose the flat roads of east Boulder for the first miles. With the first pull of the levers it was obvious this was more about merit than marketing. Initial bite is solid but not overly so. The power comes smoothly without any grabbing or dead spots and was more than adequate to bring me to halt quickly. Of course many wheels do well on flat roads, where the heat build up is minimal. For the last rides I did get into Boulder’s foothills. I meandered up Left Hand Canyon to Lee Hill, then bombed back into town along the twisty road. On my last ride I took the wheels up and over Old Stage, a notoriously steep but short climb. Both times I wanted to push the limits, but with sand on the roads and colder weather, a true test was not to be had. Still, coming down and hitting speeds over 40mph, I had every confidence in the wheels’ braking abilities. At no point was I grasping for more lever or “coming in hot”.

There is however, one very noticeable drawback. The noise. These wheels let out a high pitch shriek. From ride one it was present and it persisted throughout my time on them. Initially, it was only the front that screamed. Then, after a few corners and trying to lay on the brakes harder and longer, the noise abated. But shortly it returned, and this time it both wheels were screaming. If you were in a group ride or race, you would certainly get the stink eye. When I mentioned this to Vestal he noted that toeing in the brakes seems to help. This is something a long term test can hopefully confirm. Another issue I found was yellowing of the brake track. According to Vestal, the track is treated in some fashion (he couldn’t say exactly how), and that seemed to be wearing the Swiss Stop pads. You could probably get this coloring out with some good ol’ scrubbing, but that would be a continual task.

It’s important to note that these wheels do perform in other areas. Getting up to speed is not an issue – they spin up quickly. They also exhibit very little lateral flex. When sprinting in the drops I could not get the rims to hit the pads no matter how I tried. This stiffness also translates to crisp handling. In cross winds they are solid, though they aren’t as solid as those with the fully blunted shaped. In terms of being a one wheel solution, I would say that is an accurate claim, though I can’t fully speak to their durability.

We are hopefully going to be putting more miles on these wheels. While initial impressions are very favorable, testing these under more severe conditions is needed before giving them the full stamp of approval. If the 40 C is a solid as Mavic claims, it could very well be another wheel to consider.

The Specs

  • Rim Material – 3k Carbon with Aluminum Reinforcement
  • Brake Track – Carbon with TgMAX
  • Rim Depth – 40mm
  • Rim Width – 19mm
  • Spokes – Steel Bladed Straight Pull, 20 F/R
  • Hubs – Carbon Center w/ Aluminum Flanges, Sealed Bearings
  • Weight – 670g F/ 875R – 1545g pair (claimed)


  1. Not sure about these wheels after reading this. An overall wheelset at 40mm with a rim profile that doesn’t take into consideration of the latest technology to reduce cross winds, a 19mm inner width, really bad brake noise and a yellowing of the brake surface that you constantly have to clean doesn’t add up to me as a great overall wheelset. Oh and they aren’t exactly lightweight either. Price wasn’t mentioned in this article but for what I have been able to read elsewhere they aren’t cheap either. ZIPP can sleep easy…

  2. narrow, heavy, expensive. never mind advancing your product and listening to consumers, stick with what you know right?

  3. “The carbon is then affixed over that core using more proprietary technology. Mavic PR man Zack Vestal did say that the process is chemical and purportedly strengthens over time.”

    I can substantiate Mavic’s claim that “the process” strengthens over time: it’s called galvanic corrosion and it’s the reason I’ll never be able to extract my carbon seat post from my road bike’s aluminum seat tube.

  4. Isn’t galvanic corrosion the process when two metals (e.g. aluminum and titanium) have an electrical potential between them causing different rates of corrosion which leads to unintentional bonding?

    I think your carbon post is stuck because of good old fashioned aluminum oxide buildup.

  5. I’m unclear as to why 105 level brakes are a “compromise.” I suppose I have two initial reactions, the bike snob in me who wrenches on bikes for a paycheck since 2000 wants to say ‘well, naturally they’re a compromise, they’re not made in Vincenza, Italy (read: Campagnolo).’

    But that is largely in jest, I’m more interested to know how the 105’s are considered a weak link, after all, didn’t this same website give high praise to a Shimano SLX crankset recently for being a high return on value crank at a relatively modest price? By extension doesn’t the 105 groupset occupy the same level of proverbial polish or ranking in the road side of Shimano hierarchy for XC components? to wit: XTR, XT SLX and Dura-Ace, Ultegra, 105 from most ‘high-zoot’ to midrange. What is just so terrible about 105 brakes, please clarify.

    On another note, which is a grip against all pre-built wheels in general, not just Mavic; couldn’t you have your local shop hand build you a set of wheels that will meet your individual specifications better than any pre-made wheelset. I’m a pretty big guy in both height, weight, and riding style – I simply fail to see how the current trend towards super low spoke counts in a good thing. Wheels become harder to true, proprietary spoke wrenches and replacement parts only complicate this issue further.

    If you broke a spoke on a typical hand built wheel you can drop by almost any descent bike shop and ride home, rather than have to wait on a special order from a single distributor for a what should be a relatively simple, albiet annoying, repair.

    I run 28hole Hed Belgium’s laced to 2x to DT Swiss 350 hubs on my road bike and 36hole Ambrosio’s laced 3x to Dura-Ace hubs for CX, a 32hole Alex rim laced 3x to Formula hubs for commuting, 32hole Hed Belgium’s laced radial front 3x rear to All City New Sheriff for track. Rather than a one size fits all standard that so many companies seem to favor I just believe that every rider would benefit from wheels built for them by their local mechanic who is in touch with their customers needs, not just their desires.

    I mention the previous because I’m 5-11, and almost 100 kilos (221lbs) and am pretty sure that a 20 spoke wheel, even laced to a 40mm rim would simply have to much side to side flex to be useful under me. My point being that it’d be nice to see some data on the review themselves. If the person who authored this weighs 165lbs and stands 5-6 with a super lean physique and has a Cat 2 road licence who regularly races on Sram Red complete groups that info puts lots of clarity to a reviews take on components. This also plays into my above comments questioning why the author seems to look down upon the 105 brakes. Also of importance is where the wheels are used, what are the local road conditions like and did the reviewer ever take the wheels onto a hardpack gravel or dirt road or did they never leave asphalt. To be sure this is an initial review / impression article and the reviewer did state they had limited ride time on this particular product, so good on them for that.

  6. Thanks for the quick review. More than enough info to know to stay away from these wheels! Clearly no threat to Zipp or Enve. Mavic seems to be consistently 5 years behind the times.

  7. @Chris C: there is indeed galvanic potential between aluminum and carbon fiber, and a very significant potential at that.

  8. “They also exhibit very little lateral flex. When sprinting in the drops I could not get the rims to hit the pads no matter how I tried.”

    Stiff rims hit brake pads. Flexible rims don’t.

  9. Evan, what a strange post. Don’t buy them if you’re fat and break wheels all the time. I don’t think that the author should even have to state that.

  10. They look great, and I’m sure they’re durable, but once again, there’s the question of what slot this fills in a crowded market segment. Enve prices, Ksyrium weight, and sounds like inferior braking to both.

    Evan-105 brakes are not as good as Ultegra or Dura-Ace brakes. They’re better than Sora or Tiagra brakes. I believe that’s what AJ meant by compromised. Gravity’s right, you’re probably not in the target demographic of these wheels, and that’s ok, but it shouldn’t necessarily be held against the product.

  11. Gravity; well… I lift 4x times a week and have a pretty good APFT (Army Physical Fitness Test) score. I’ve also repaired many a wheel trashed by lightweights to include Roval, Stan’s No Tubes, Mavic, Bontrager, Kinlin… the list goes on.

    Your reply, while amusing fails to discuss the merits of wheel strength, stamped vs. extruded spokes, eyeleted rims, spoke count, spoke lacing theory, spoke wind-up issues, straight pull vs. J-bend spoke design, and well… the list goes on.

    Riders break wheels / spokes / bend rims all the time based mostly on their personal maintenance schedules and riding location I’ve found. For example, I never broke a spoke on Spinergy Spox wheels (jump with me in the way back machine to the early 2000’s) and I never took those outside of downtown Chicago from before the days of bike lanes and cycling aware drivers. For that matter I’ve never broken a spoke on any of my wheels ever, to include a set of Specialized Roval Fusee SL 25’s, which I was well over the weight limit for and I’ve had customers who weigh about forty, fifty pounds less than me break spokes on them to the extent we sent the wheel back to Specialized for repair rather than work on it ourselves (older generations of Roval wheels required that you de-tension the entire wheel in order to replace a broken spoke and / or nipple). I believe this backs up my preventative maintenance theory seeing as we both rode in the same region at the time he broke them.

    Furthermore, I know a Cat 2 roadie with a lean physique who’s Alpha 340 requires constant attention despite a 32hole 3x drive side 2x non-drive setup. Power output drives (no pun intended) the majority of spoke pull-through breakages due to spoke tensioning. His high power output simply puts to great a demand on thin rims who’s spoke bed isn’t thick enough. Yes, this is on a 2nd gen Alpha 340 rim with the thicker spoke bed as well, Stan’s redesigned the rim in 2011(?) for reasons I am unaware of, but presume due to the high number of failures it had, they also introduced a Alpha 400, i presume, to create a more abuse worthy rim as it has additional bracing at the spoke bed as part of the extruding process.

    The lower the spoke count, the higher the tension needed on the spokes – ergo the increased force on the nipple and rim drillings along with the flange on the hub. similarly radial lacing puts excessive stress on the hub flange, this is why many hubs have their warranties voided if you do so.

    To the eagle eyed reader; you’ll notice I’m running a 32 hole All City new sheriff laced radial on the front wheel as mentioned in my first post. All City states that their hubs will have their warranty voided if the wheel is constructed as such, to which… QBP didn’t have the spokes in stock that I needed to build it up 1x, so I said ‘screw it lets see what happens’ and built the wheel all elbows out / heads in (on purpose). This increases the effective diameter of the hub flange and thereby increasing the side to side stiffness of a radial wheel at the cost of increased stress on the hub flange (read: reduced life).

    So, I’ll buy your ‘to fat’ argument if the wheel fails on me when I do intervals in traffic. To everyone else; hope you’ve picked up on some of the finer details of spoked wheel construction and some understanding of the merits of different lacing styles and philosophies.

  12. Given that Evan T’s comments are completely irrelevant, it’s hard to see Mavic’s strategy here. Between the weight of the wheels, the price, the narrow rims, and the comparatively shallow (with respect other aero rims), it’s tough to see who exactly is in their target market.

  13. i think MAVIC can afford to produce a wheelset like this. Its really amazing to me to think of a “one wheelset/do it all” when aiming at this market segment. I suppose if there was ever such a thing, it would be a kin to an aluminum 30mm wheel, like Williams System 30, CXP 33s, etc…

    I suppose somewhat contrary, its really hard to beat a set of Ksyrium SLs. While obviously not the best TT wheel, they really work in a group, and if its time for a kick, they spin up pretty quick, taking a flyer in anything other than perfectly still conditions… I’m always amazed how effective Ksyriums can be.

    Cosmics in the day, where awesome. they still continue to be a good wheel, its just that the competition has closed that gap on buzz saw wheels, and arguably there is a learning curve to driving aero wheels. Albeit, these days, most experienced cyclists have had a fair taste of the allure of deep dish carbon.

    I think coming out with a wheelset like 40C is great. someone will buy them, obviously the segment begs for evolution. With that said, I would guess, MAVIC is loosing the high end carbon aero market to its competitors.

    After over 2 decades of using MAVIC stuff, its really hard for me to not be a fan of their product. But… it seems there are better offerings for certain things.

  14. Devo-

    Ksyriums are great, as are most Cosmics, but Mavic is not infallible. See the first R-SYS, Mektronic, their pedals, their computers…

  15. I think it’s set-up sounds right for an everyday boutique wheel where one is trying too balance weight, aerodynamics, braking and road feel.

    At under $2K, I think they would have a winner. Not sure if their pricing strategy makes sense given the competition and its benefits.

    Mavic is stuck with a less sophisticated shape than its competitors (Enve, HED, and Zipp), but perhaps novel approach to addressing the safety downsides of carbon clinchers.

    Personally, I’d probably opt for the Zipp 303s given roughly equivalent pricing.


  16. plenty of mfg have had their ups and downs. I’ve been fortunate to live in Monterey, Ca, where once upon a time VelTech was once located. MAVIC, not so happy with that big plastic (derelin or whatever it is) bushing that is used in their freehubs. Crazy happy with? when CrossMax Tubeless came out, in the day it was a huge change for me. thank you MAVIC and Hutchinson.

    another no like of MAVIC that I was glad to steer clear of, was the initial Heliums. Seemed like every set that crossed social paths, had some kind of issue.

    MAVIC, not perfect that is for sure.
    Caveat emptor

  17. I think I prefer my Reynolds CC’s. I have the 66mm for my road bike and 81mm for my tt machine. I’ll be upgrading to the new wider Aero 72mm and 90mm this year.

    Mavic, in my opinion, don’t make products that are ground breaking. They have a huge following in Europe and people just seem to buy their stuff. I think in general, those of us in the U.S are more technically savvy when it comes to our choices in equipment.

  18. Why would anyone buy these?
    They’re NOT cheaper than the competitors, they weigh more, they’re not a deep as others and they’re NOT a full carbon wheel.
    It’s an aluminum rim wrapped in carbon?

    A waste of time even thinking about them.

  19. Hey Gang,
    I’m going to take a big risk here and jump in with a comment. I’m the PR guy referenced in the story. You also may know me from my prior occupation at VN. If you already hate me, I am sorry I did or said something to offend you. I fully expect your wrath and displeasure, but I would invite you to engage in open dialogue if you are genuinely curious about these wheels.

    AJ didn’t get a good test ride period, but I will try to address some of his comments and yours.

    For starters, here’s how I answered some questions and concerns of a similar nature over on the weight weenies forum:
    I can address what’s been a recurring theme: what’s so special about 40mm carbon clinchers, with weight per pair over 1500g? And, why bother to use carbon at all, going to all the effort when alu is ususally better?

    We would address that by emphasizing the following points, which in total contribute to wheels which are not just cosmetic but actually bring some really nice ride characteristics.

    – Mavic took great pains to quantify braking performance, and if you take a chance to ride the wheels, you’ll note that dry braking is exceptional and doesn’t fade. Wet braking is like no other carbon clincher – it’s revolutionary. I don’t know how they did it precisely, but when you feel the sidewall you will feel a surface that’s unlike most others. Coarse, raw, like that.

    – wheel weight per pair is not heavy, in fact when you measure competitors with the rim strips that they’re required to use, the weight of 1550g is actually in line with wheels in category. It’s below Reynolds and only 20g over 303.

    – taken alone, the rim weight is 50-60g below that of competitors, who are typically measured without the rim strip (which they in fact require!). So with lower rim weight, Mavic has made a wheel with the characteristic “Mavic ride feel”: stiff, rapid acceleration and low inertia.

    – lateral stiffness on the bench test (measured in mm deflection per Newton load) is better than competitors, and has been tuned for minimal movement at 180 degrees (no rub at the brake pads). In fact by this measure the CC40 is better than almost all competitors.

    – aerodynamics are good – better than CC SL/SLE/SLR (which are 12mm deeper). Almost (but admittedly not quite) as good as 303. Zipp 303 measures lower drag at 10 deg, but more after 13 deg. So the CC40 will offer more predictable handling with less variation in drag across a full yaw sweep.

    – the carbon wrapped up the sidewalls of the aluminum tire bed is 100% structural. The tire bed insert is too thin on its own to support tire pressure and impact resistance.

    – The advantage of the aluminum insert is precise tire fitment. No chance of the Stan’s or MF tire blow-off that is relatively well documented. In fact, Mavic has taken GREAT pains to respect the ETRTO standards for tire bead dimension and fitment. Both for rims AND for tires, too. Imprecise tire-rim tolerance, especially on the tire side, is responsible for more failures than you would even imagine…. Hence, the WTS “MAVIC tires included” program that Mavic is adament about. It’s one more measure of tested, proven, known and trusted performance and QC by the rigorous lab and field protocols in Annecy.

    – You’re right if you say that carbon and aluminum have much different rates of thermal expansion. I do not know the precise nature of the bond between these two materials in the CC40, but I’m told it is chemical and in fact it grows stronger over time.

    – regarding the width, it’s clear that wide rims improve aerodynamics but that wasn’t the #1 goal with CC40. Good all around performance and handling was the key, and the width is in line to deliver that. Perhaps in the future, different widths can be explored but for now proving the durability and maintaining the brake performance were paramount.

    I think the take-home on Mavic’s side would be this: if you’re looking for a carbon clincher, for whatever reason, you should consider safety and reliability first. Then, look for exceptional ride characteristics: braking, accelerating, stiffness. That’s what the company did, and we think if you ride the wheels you’ll actually notice the effort that was made.

    Now – regarding specifics in AJ’s story, I can add the following:
    – brake pad noise – diminishes significantly with a little brake adjustment and a little time bedding in. Also, the brake pad residue on the rims does wash off.
    – long term durability – whether a blessing or a curse, Mavic is measured to a standard established by the Ksyrium wheels introduced over 10 years ago. Many riders report them needing not a single spin through the truing stand for upwards of 7 years. This is the level of strength and durability built in to all the wheels, and the CC40 are no different. For this reason their weight (and Mavic weights in general) will be competitive but rarely outright lighter by wide margins.

    I would encourage you to test ride the wheels some time. I can be reached by private message on weight weenies. best regards and happy rides- zack

  20. Do not underestimate the Mavic. The time that it has the racing experience is greater than the length of Companies all togheter…

  21. I just purchased this set. SOO excited about these. I’ve ridden Mavic wheels for years and absolutely love the old Cosmic wheels I’ve ran. We ran Zipps for some time but the braking on our downhill descents just wouldn’t hold up to what we do. We lost three Zipp wheels last year.

    I should have them shortly and will have some good solid real world data. We’ve been waiting for these for some time. Really excited!

  22. I am seriously considering these wheels, I currently ride Reynolds Attack & Assault and had the attacks rebuilt last year only to blow another spoke last night. I did a major climbing ride on the attacks 3 weeks ago (3 Mountain 3 State) and nearly shat myself cause of poor breaking in the rain. I have a friend who rides them and loves them and can stop in all weather. Admittedly his wheels were crazy loud setting in but overall he loves them. Am I crazy, If not these wheels, what other options?

  23. These are great wheels. Very fast and surprisingly awesome in crosswinds. Not super spunky climbing (to be expected) but all around great. They brake every bit as good as the alloy wheels (Mavic & Shimano) on my other bikes even on big 40mph+ descents.

What do you think?