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Mavic Cosmic Carbon 40 wheels



Excellent durability & stiffness and top-notch braking but not light and quite pricey

At every product is thoroughly tested for as long as it takes to get a proper insight into how well it works. Our reviewers are experienced cyclists that we trust to be objective. While we strive to ensure that opinions expressed are backed up by facts, reviews are by their nature an informed opinion, not a definitive verdict. We don't intentionally try to break anything (except locks) but we do try to look for weak points in any design. The overall score is not just an average of the other scores: it reflects both a product's function and value – with value determined by how a product compares with items of similar spec, quality, and price.

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Surprisingly, the Cosmic Carbon 40 Cs are Mavic's first ever carbon fibre clincher wheels. They're fast and stiff, with dependable braking performance, but the high price is hard to digest and they're not especially light.

There's a huge appetite for carbon clinchers these days; people want the looks and speed of carbon deep-section wheels, but with the convenience of clincher tyres.

Alloy and carbon fibre construction

The biggest issue though with carbon clincher wheels, and all carbon wheels for that matter, is heat generated when braking. Drag the brakes long and hard enough, and you'll soon heat up the carbon and resin mix to the point that they could fail. And that doesn't tend to happen without fairly catastrophic results.

Mavic has a novel solution. Where the likes of Zipp, Enve and Reynolds use a 100% carbon fibre rim, Mavic has developed an alloy extrusion wrapped with a carbon fibre shell, and injected the cavity with foam. Mavic has lots of expertise with alloy rims, and knows that aluminium is better at dissipating heat than carbon, so felt this was the best approach.

Very simply, this alloy rim bed insert acts like a sort of heat sink, drawing the heat away from the carbon braking surface. That's not all. The alloy rim core adds structural integrity to the rim, which leads to a truer rim that should avoid the pulsating that can sometimes occur with one-piece carbon rims. Durability and stiffness are other benefits of this manufacturing approach too.

This alloy core is wrapped with a 40mm carbon fibre rim. The brake track is then finished with Mavic's proprietary heat treatment process, involving two types of resin in the braking surface. It calls this TgMAX technology, and claims the Tg point (glass transition temperature is the point at which the resin gets hot enough to revert to its liquid state) is able to exceed 250°C. They tested this with a 100kg rider on a 10km downhill.

Not only does Mavic claim this creates reliable and consistent braking performance, and shorter stopping distances, in the dry, but it also claims much better performance in the wet, too.

The 40mm deep rim has a V-shape profile with a 19mm wide rim bed. Mavic's Fore technology uses threaded inserts at the rim, there are no spoke holes in the rim bed, and bladed aero double butted spokes connect the rims to carbon-bodied hubs. There are 20 radially laced spokes (2-cross on the rear driveside) in each wheel.

No hidden nipples mean you don't need to remove the tyre and rim tape to adjust the spoke tension here. The hubs aren't anything to get excited about, they're the same as used on other Cosmic wheels in their range. Inside the hubs are Mavic's QRM+ bearings. The bearing preload can be adjusted without taking the wheels out of the bike.

Mavic continues to push its concept of a wheel-tyre system, and supplies the wheels pre-fitted with a pair of its own tyres, Pro Griplink on the front and Powerlink on the rear, front- and rear-specific tyres. I've been impressed with Mavic's own tyres and these are pretty good, but there are better aftermarket tyres available.

The wheels weigh 1,596g (front: 687g, rear: 882g) on the scales that don't lie. That's a little more than the claimed 1,545g. Look at the competition though and the Mavic wheels, it has to be said, don't fare so well: a pair of Zipp 303 Firecrest wheels is a claimed 1,475g. However, the Mavics are significantly cheaper than £2,300 retail price of the Zipp wheels. Or you could throw in the recently reviewed Reynolds Aero 58 clincher wheels, with a 1,601g weight and £2,100 price.

The ride: Fast and consistent braking performance

To put the wheels through their paces, I've been riding them constantly as everyday wheels over the past six months or so, racking up thousands of kilometres on them. Riding them in the pouring rain, down muddy tracks, bashing through potholes. And through it all, they've not put a foot wrong, they've been solidly reliable and durable. I'd half expected a few blemishes to be revealed in that time, but no, nothing.

As for the braking performance, well it's very good. I've yet to ride a carbon fibre wheel that has amazing braking performance, it still feels just too much of a compromise. While I don't think Mavic has nailed it, they've produced a wheel with more consistent, predictable and reliable braking than a lot of carbon clinchers currently available.

There's plenty of bite when you pull hard on the lever. You can slow down on a steep descent pretty quickly if you need to, but like most carbon wheels, you do need to plan ahead a bit more than you don on alloy rims. When you really need to, the Mavic's quickly scrub off speed, you can rely on them, have confidence in them.

The best aspect of the braking performance is they are smooth and progressive, there's no snatching or pulsating feedback through the brake levers, and in that regard they feel a bit like an alloy wheel. Mavic claim they're good in the wet, and they are, but there's the same drop off in retardation you get from most carbon wheels in the wet.

In my testing they do deal with heat well. I have more confidence dragging the brakes or working them hard on a descent if I really have to, compared to other wheels I've ridden. That testing hasn't included a trip to the Alps or anywhere with a really long descent, though.

As for speed, well put simply that is hard to draw a conclusion on. doesn't have a wind tunnel for me to do some comparative testing, so I'll just leave you with my impression that I found them nippy and quick. Clearly they don't have the on-trend wide and bulbous rim shape that seems to be prevalent in the wheel market, but they felt fast compared to other carbon wheels and against a regular alloy wheel, but the differences we're talking about are marginal at best. You're not suddenly going to travel 5kph quicker by bolting these wheels into your bike.

While they don't have that sensational sense of speed that some deeper section carbon wheels give a bike, the upside of the 40mm rim depth is that they handle a range of cross-winds without any adverse effects. They're very stable with a direct side-wind. I'm a light rider and really notice cross-winds and I usually fear riding deep-section wheels in windy conditions, but in the recent storms I have been fine on these.

What they might lack in speed, they make up for in responsiveness. They respond far more keenly than most deeper section wheels, there's none of the lag or flex that some deep section carbon wheels exhibit when being pushed hard. Sling them about the road, get out of the saddle and heave on the bars, and they track sharp and clean. They noticeably lifted the handling performance of every bike I tried them in too.

They're a delight to push through corners as well, where that stiffness really comes into play. Happily, they're quite controlled over rough roads and didn't produce a harsh ride at all. They're also a very quiet set of wheels; some deep section carbon wheels can create quite a backdrop of whooshing noises. These didn't, though they were a bit noisy during braking at first, but that soon disappeared.

A slight drawback that will be of more concern to some people is the 19mm internal rim width, which is narrow compared to what a lot of the other wheel manufacturers are leaning towards. They're not designed with wide tyres in mind, but I had good results with a 23mm tyre fitted.


Great wheels with excellent durability and a very high level of stiffness contributing to a responsive ride, and the braking performance is top notch too. Not the lightest and certainly not cheap though. test report

Make and model: Mavic Cosmic Carbon 40 Wheelset

Size tested: n/a

Tell us what the product is for, and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?

The best combination of reliability and lightweight for the most versatile aero wheelset. Thanks to the exclusive TgMAX technology, Mavic's carbon clincher solution is the most reliable and dynamic clincher wheelset ever.

Tell us some more about the technical aspects of the product?

Dimension: 23-622 (700x23c)

Front and Rear Tread: Dual Compound

Max. Pressure: 9 bar / 130 psi

Casing: 127 TPI

Breaker: Strong Nylon

Link: GripLink

Link: PowerLink

Yksion Pro Griplink (front) & Powerlink (rear) - 190g

Count: 20 front and rear

Lacing: radial front and rear non-drive side, crossed 2 rear drive side

Material: steel

Shape: straight pull, bladed, double butted

Rate the product for quality of construction:

Impressive construction

Rate the product for performance:

They're not the quickest, neither are they the slowest.

Rate the product for durability:

They're bombproof; I've tried to break them, but they just won't have it.

Rate the product for weight, if applicable:

Yes, here they don't score so well, but some of the lighter carbon options are more expensive so that's got to be taking into consideration. Against an alloy wheelset, it's no contest.

Rate the product for comfort, if applicable:

I was impressed with how well they deal with rough road surfaces, they're not harsh or skittish at all.

Rate the product for value:

They're clearly a lot of money and there are many carbon clincher wheelsets for a lot less than the Mavic RRP, but they pack a lot of technology and the stiffness and braking performance is better than a lot of the cheaper carbon wheels.

Tell us how the product performed overall when used for its designed purpose

Very well.

Tell us what you particularly liked about the product

Stiffness, great handling, durable, good braking performance.

Tell us what you particularly disliked about the product

Don't feel especially quick, and they're not especially light either. A tough sell.

Did you enjoy using the product? Yes.

Would you consider buying the product? Hmmm

Would you recommend the product to a friend? Hmmm

Anything further to say about the product in conclusion?

As good as the Mavic wheels are, and I've been very impressed, they just don't feel amazing and joyful to ride, and I can't help feeling that an alloy wheelset can be had for the same weight, or less, with a hefty saving, and not really be a great deal slower. If you have your heart set on a carbon clincher these are a good option for your shortlist. You won't be disappointed. But you might not be blown away either.

Overall rating: 7/10

About the tester

Age: 31  Height: 180  Weight: 67

I usually ride:   My best bike is:

I've been riding for: 10-20 years  I ride: Every day  I would class myself as: Expert

I regularly do the following types of riding: road racing, time trialling, cyclo cross, commuting, touring, mtb,


David worked on the tech team from 2012-2020. Previously he was editor of and before that staff writer at RCUK. He's a seasoned cyclist of all disciplines, from road to mountain biking, touring to cyclo-cross, he only wishes he had time to ride them all. He's mildly competitive, though he'll never admit it, and is a frequent road racer but is too lazy to do really well. He currently resides in the Cotswolds, and you can now find him over on his own YouTube channel David Arthur - Just Ride Bikes

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mike_ibcyclist | 9 years ago
1 like

I got these yesterday and set them up for a morning 60km club ride today. Overall impressions are that these are really solid wheels. The rims don't have that hollow feel of my Campagnolo Boras or my previous Mavic CC SLR's. No idea if thats good or bad, but I gave the brake surface a touch after a couple of steep fast decent and they didn't generate anything like the heat I get from my Boras. Climbing wise they felt good, not amazing. No flex out of the saddle. Impressive given I'm 93kgs riding these on their limit.

Regarding setup. Mavic instructions are awful. In the booklet it suggests I need to use a spacer on their ED11 cassette for Campy 11. That is wrong for newer wheels like these. They also include a lockring, but don't say why. Apparently this is because the Campy 11 tooth cassette locking doesn't fit the Mavic ED11. Bizarrely nothing regarding this in the booklets I got with the wheels. For 12 tooth smallest cog, just use the Campy lockring.

BTW - I got these for approximately GBP1100, thanks to the fact that I exported from the EU (save 20%) and took advantage of a sale. I luckily paid no import duty into Australia because customs for bike parts is in my experience sporadic at best. Even so that would have only added about 10% to a great price. Shipping is included in my numbers.

As for the brakes. The usual new brake noise even though I toed them in. Beware the yellow pads leave residue on the surface. I cleaned what I could with some rubbing alcohol, but it's not perfect. I've seen some suggestions about sand paper and scotch Brite pads in forums, but I'm not going there. I used the same alcohol to clean the pads themselves and finished by wiping with a damp cloth.

If you're new to Mavic's top end wheels you've got to keep in mind that you need to service the free hub every month or so. Failure to do this will cause wear on the rear axle as happened to me with my CC SLRs, and you'll have to buy a repair kit to extend the wheel life. It's an easy process, takes about 15mins max once you know what you're doing.

mythbuster | 10 years ago

Alloy extrusion covered in carbon fiber is hardly novel, or Mavic's invention. Several smaller manufacturers have been using this technology for at least 5 years now.

David Arthur @d... replied to mythbuster | 10 years ago
mythbuster wrote:

Alloy extrusion covered in carbon fiber is hardly novel, or Mavic's invention. Several smaller manufacturers have been using this technology for at least 5 years now.

It is novel compared to the popular mainstream wheel choices, examples of which I included. I didn't say it was their invention. Care to mention these manufacturers?

ourdave | 10 years ago

I would also love to see a review of the new Reynolds Assault SLGs. They look to be a relative bargain!

Oh, and the term you are looking for is heat 'sink'!  3

Jez Ash replied to ourdave | 10 years ago
ourdave wrote:

I would also love to see a review of the new Reynolds Assault SLGs. They look to be a relative bargain!

Ahem. Watch this space. For a little while.

allez neg | 10 years ago
1 like

Would it be beyond the capabilities of a wheel company like Mavic or Shimano to make a wheelset with an alloy rim, and then a selection of rim fairings of varying depths that could be fitted to give the aero benefits?

Not for the pros, but us normal bods.

700c | 10 years ago

Seems like a lot of compromise just to make clinchers out of carbon that won't melt or explode down steep descents..

If you're going to spend 1800 quid I still think you'd be in the market for tubs, which would be lighter and probably ride better.

That said, I do quite like the way the tyre profile is flush to the rim -having seen a pair on sale at the w/e. I suspect that alone gives some aero advantage..

flexcamp | 10 years ago

Planet X 40mm or 50mm carbon clinchers, Dura Ace C35 or even Mavic's own Cosmic elite? oops, the the Elite aren't carbon! but they are reasonably light, very strong and super stiff...and silly cheap!

Metjas | 10 years ago

how would these compare to the new Reynolds Assault 41mm carbon wheels at 1475g and around £1200?

TheFatAndTheFurious | 10 years ago

£2000 = "quite" pricey?  13

I don't fit the target demographic for this one!

Got any sub £300 wheelset reviews coming up?  105

JimboBaggins | 10 years ago

£2000 doesn't seem quite right - isn't RRP £1800? Most shops give you at least 10% off. I bought mine for £1530 and am very happy with them...super-stiff, great braking, "feel" aero (I have Zipp 303 tubs too, and these don't feel slower on the flat, although they are heavier up hills). And they come with tires, tubes and bags which some competitors don't. I am sure you can get very good wheels for lots less, but sometimes a treat to yourself is OK, right?...

notfastenough | 10 years ago

Granted re the Maserati, but why wouldn't I pay half this price for a pair of Dura-Ace C35's? That would also get me an alloy braking track, with the only penalty (notwithstanding any differences in aero performance, which I can't assess) being a whopping 31g weight increase.

russyparkin replied to notfastenough | 10 years ago
notfastenough wrote:

Granted re the Maserati, but why wouldn't I pay half this price for a pair of Dura-Ace C35's? That would also get me an alloy braking track, with the only penalty (notwithstanding any differences in aero performance, which I can't assess) being a whopping 31g weight increase.

exactly, nobody is holding a gun to your head to buy them.

never get why the hoooooooooow much!!!!! brigade comment on every single premium product.

people buy what they can afford and makes them happy

i run a set of 50mm handbuilt carbons that cost £500 ish, im happy with them and they are likely at least as good as these(lighter for sure!)

but some people like to stick to brands for whatever reason suits

im not a mavic fan but thats my choice, i dont go slagging people off who do choose to run them.

laterrehaute | 10 years ago

It would be interesting to see a comparison between these and say Planet X CT45 for quality, durability and stiffness.

DeanF316 replied to laterrehaute | 10 years ago

Easy to compare Mavic make their own in own factory sold with a UK based service back up and 2 year warranty and the others are made by unknown i in the far east.

morethansonglyrics | 10 years ago

Seems like a rip-off. You can get cheaper, lighter carbon for a quarter of this price.

ajmarshal1 replied to morethansonglyrics | 10 years ago
morethansonglyrics wrote:

Seems like a rip-off. You can get cheaper, lighter carbon for a quarter of this price.

You can get absolutely anything cheaper in any walk of life if you look hard enough (to a degree), but that's not the point is it? A Kia may be cheaper and more reliable than a Maserati but I want the Maserati.

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