The Mavic Cosmic Pro Carbon SL UST is an update of the Cosmic Pro Carbon SL C, Mavic’s first medium depth rim brake wheelset using only carbon fiber and resins in its brake track.

In going from “SL C” to “SL UST”, Mavic widened the rims, put on new hubs, and built it to their new UST tubeless standard.

The result? The new Mavic Cosmic Pro Carbon SL UST is a more comfortable, quieter, and more tubeless-ready wheelset. It’s clearly an improvement over the SL C it replaces and that I reviewed with the headline – A strong, noisy performer at a good price.

The SL UST is 2mm wider than the SL C, now 19mm across the inside of the rim (measured between the bead hooks). I could feel the added comfort in the ride. This is especially so with the Mavic Yksion Pro UST 25C tubeless tires that are included in the price of the wheels and come pre-installed. These are also better tires than Mavic supplied with the wheels before.

Compared to the much-heralded Schwalbe Pro One tubeless tires, the new Yksion rates equivalent in rolling and puncture resistance (see tubeless tire ratings here). In my experience, these tires also have a better road feel and their aerodynamics are better for this wheelset (and many others). The mounted and inflated width for the 25C tire is a mm narrower than the Schwalbe and closer to the wheels’ 25.5mm external or brake track width.

Mavic Cosmic Pro Carbon SL UST Rear Wheel

The Mavic Cosmic Pro Carbon SL UST hubset is also new but, according to the word out among shop mechanics, is a knock-off of DT Swiss 240 hubs used on many other carbon road bike wheels. Whatever the hub’s heritage, the new Mavic hub is smoother and quieter than the noise created by the SL C hubs while retaining the distinctive Mavic freewheeling sound.

This is real progress if you care about freehub buzz. We’re talking about going from it’s really annoying; don’t buy it to something like it’s acceptable if you like to hear your freewheel spin.

Mavic continues with the same version of their textured brake track on this Mavic Cosmic Pro Carbon SL UST wheelset that was used on the SL C. At the speeds I ride (18-20mph on an average training or group ride), I found it gives you good braking on dry pavement but is not very good on wet roads.

My fellow tester Nate rides considerably faster (23-26mph) and challenges wheelsets a good deal more. He was unimpressed with the braking power and heat dissipation of these wheelsets down long, steep alpine descents. We both noticed they squeal after warming up.

While these new Mavic Cosmic Pro Carbon wheels climb well enough, this kind of braking seriously dulls the reward you’ve earned from climbing when you are looking to cash in doing a long downhill. They do handle well in the crosswinds you often find in high mountain passes or those coming across open spaces.

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While they are clearly stiff when you want to turn up the speed or head up a ramp, they aren’t lively. There’s no snap and little giddy-up when you want to accelerate or get out of the saddle.

They do hold their speed well once you get moving but nothing out of the ordinary.  The same can be said for their handling – solid but not inspiring aggressive riding in the corners.

Over the year or so that Mavic improved these wheels, other well-established wheel makers like Zipp, Bontrager, Roval and DT Swiss were also improving the design and performance of their hoops with new or updated wheels in this carbon clincher wheelset category popular with serious roadies. Lesser known brands and those sourcing and selling carbon bike wheels designed and made by others have also pushed further into this category at the same time.

The market price for this wheelset of around $2,100/£1,700/€2,000 puts it in a tough spot as it doesn’t match up against others in a similar price range. You can find and order it using these links to my top-ranked store Competitive Cyclist, at recommended store Planet Cyclery, and at other recommended stores at Know’s Shop.

You don’t have to spend a whole lot more to get much better performance and you can spend a lot less and get performance nearly as good. If you don’t have the budget for better performing carbon road bike wheels or if you value Mavic’s extensive dealer network and aren’t going to ride them as hard as a Group A rider like Nate, this solid wheelset will work for you.


This review appears alongside reviews of similar wheels in the post THE BEST CARBON ROAD BIKE WHEELS



First published on August 23, 2018. Date of the most recent major update shown at the top of the post.

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  • Christopher Titus

    Interesting review. I appreciate your in depth reviews in general but, as an owner of these wheels , do disagree with some points. Coming off Mavic ksyriums these seem to have plenty of snap and get up and go so to speak and have found the braking to be adequate. Cleaning the pads helps keep the braking more reliable I’ve found. I realize you are comparing them to other carbon wheels however. I tried a set of Enve wheels last year which for what they cost vs. ride/perfomance meant there was no way I was going to buy them. I am curious how the new Zipp 303’s campare to these Mavics however but I am very happy with these wheels so far. Thanks for the reviews!

  • Thanks for doing the work on reviewing these Steve. Was looking forward to hearing your thoughts on this set, a bit disappointed, was hoping it would be a bit more positive. Solid but boring doesn’t sound like fun. Hard to settle for when it’s such a big expense.

  • Few months ago I tested this Mavic wheels, and I had the same conclusions that you got.
    For me another disappoint it’s the max pressure of 6bar, I think It’s too low, in particular for the heavy riders.
    I must admit that, there’s many cheaper wheelset equally performing.

    I can sugget to you to consider anothere element in your evaluation? The weight of the cyclist. Many of us are overweight and these may cause as big a change of the reaction of the wheelset.

    • Mauro, thanks for your comments. Moose is our heavyweight tester (about 200lbs/90kg) and had a similar reaction to these wheels. Steve

  • I don’t see any mention of the depth of these wheels ?

  • Stephen – per my measurements: 40.4 mm deep,19.1mm inside, 25.5mm outside, 1533 grams. Steve

  • Steve,

    How would you rate these wheels in the disc version which negates the rim braking negatives?

    (FWIW I have the 2016 version of these wheels with same rim braking surface and find they work very well in the wet providing the recommended pads and braking surface are regularly cleaned. I do this whenever I clean the chain by using fine grade sand paper / file on the pads and a baby or degreasing wipes on the braking)

  • Steve, It seems Mavic have released a updated disc version of this wheel which is now 45mm deep and 28mm wide.

    Wiggle and others are now selling off the 40mm which I think is the disc version of the wheels reviewed here.

    Has this new wheel come across your workshop and do you have any intel?


    • CA, Not yet but I’m trying to get a hold of a set. I don’t expect the rim brake model to be updated from the one I reviewed above anytime soon. Disc and rim are on different development paths at most of the better wheelset companies now. Steve

      • After looking at this further, I’ve learned that the wider disc brake version you linked to will be replaced by one with a 21mm internal rim width (as is the new Ksyrium Pro Carbon SL UST Disc) at some point rather than the 19mm internal rim width it has now. So, I’ll wait to review the new one whenever it comes out rather than the one you linked to. The rim brake version reviewed above will stay a 19mm internal width rim. Steve

        • Steve – thanks for the update and well spotted… Was about to order the new (now it seem old) 28mm wide (19mm internal) for a good price as part of a new bike build. I saw the wheel in the flesh yesterday and the 25mm tyre seems well integrated and aero.

          What is the downside of the 19mm vs 21mm internal rim assuming everything else is the same? I really fancy the mavic tubeless system and support in France. Will be keot in a small mountain village and used for endurance event in the Alps – I am a steady climber 800 – 1000 VAM on long climbs and not an accelerator up hill – more yak than goat.


          • PS. As reference I find my 2016 Cosmic Pro Carbon SL quite acceptable for my needs – I believe this is the first generation of this wheel.

            Open to alternatives including the new new ksyrium Pro Carbon SL

      • Charles Custodio

        Hi Steve.

        Would you recommend the Mavic Cosmic Pro Carbon (non-SL) UST or even the previous-gen Mavic Cosmic Pro Carbon SL C wheels over the Zipp 302?

        I don’t plan to go the tubeless tire route anytime soon.


        • Charles, I wouldn’t. I tested that earlier SL C and found them quite average. Similar to the SL UST but with a louder (annoying) freehub that didn’t seem to maintain momentum or brake nearly as well as the 302. Steve

          • Charles Custodio

            Got it Steve. Will check on the Zipp 302 prices from your suggested online retailers.

            Thanks for your reco!

  • Great review as always Steve! What are your thoughts about the Cosmic vs. mavic ksyrium pro carbon ust disc. Any advantages of the Cosmic over Ksyrium?

    • Ahmed, can’t really answer that question without some context about what you. Best if you look at your goals, riding profile and budget. See here to help you figure it out. Also, Mavic’s has Pro Carbon UST and Pro Carbon SL UST in its Cosmic and Ksyrium lines which are different wheels. Very confusing names. Bottom line, you can do better than Mavic for most (all?) categories of wheels and I would urge you to look at other brands for wheels that suit your goals, profile and budget. Steve

  • You mentioned that you can get a much better performer for not much more money. Please provide some suggestions. I’m 5-10 and 142 lbs so weight is not an issue but out of the saddle climbing or just hard efforts is. I have found that many carbon wheels, especially Reynolds Assult and the new AR41X flex way too much.

  • Hi Steve – this is one of the few wheels that is available as a rim only. Mavic CXP Pro Carbon UST Disc Rim (19mm inner, 28mm outer, 45mm deep). It ‘looks’ to me like the rim is following the aero philosophy of Zipp, but hard to say. It seems the criticism of the wheel isn’t in the aero performance, but the build. A custom built wheelset would be half the cost of an ENVE set. With nice disc hubs and quality lacing, maybe the wheels would be more lively.

  • Hi Steve

    An online retailer has the non sl Mavic Cosmic Pro UST for £699 at the moment.

    I think they use a different hub and weight a bit more at 1650g.

    Are they worth considering at this price point (40% off). There’s not much branded available for the money.


    • Tom, That’s like the prior model that, for whatever reason, they still have in inventory. I also reviewed that wheelset and replaced it with this when it stopped being made. I liked it even less than this one. The hub wasn’t great and was very loud and the wheelset didn’t perform well compared to wheelsets from other brands of similar depth. It was Mavic’s first all-carbon wheelset. Personally, I would put that amount into a better wheelset rather than spend it on one you probably wouldn’t be happy with. Steve

      • Hi, it was this set here, UST but not SL. They are a 2020 model but different hub I think. Still wide internally and were down at possibly a fairer price point

        • Tom, Thanks for the added info. Sorry, I don’t know that wheelset but if it looks like a heavier wheelset than the SL with a pawl mechanism hub vs the better ratchet one on the SL. And it’s £969, an 11% discount not £669. So I don’t imagine it performs as well as the SL, which I thought was only an average performer in the first place and is not much of a deal. Steve

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