MAVIC COSMIC PRO CARBON SL CLINCHER – A STRONG, NOISY PERFORMER AT A GOOD PRICE
The following review is part of the post BEST CARBON CLINCHER WHEELS
Despite the growth of a new, high-end wheelset market with the breakaway success of carbon clinchers since the early part of this decade, Mavic went out the back of the pack with its seeming unwillingness to offer a model to compete. The closest they came were wheels with an aluminum insert underneath the otherwise carbon rim in an attempt to absorb heat energy coming from braking. Mavic’s view was that an all carbon wheelset wasn’t totally safe, something that most riders of first generation carbon brake tracks would agree with.
It appears that hiring some new engineering talent a couple years ago has given them an opportunity to come up with some new designs to get back in the bunch with the introduction of their first all-carbon wheelsets, the 40mm deep Mavic Cosmic Pro Carbon SL-C (clincher) for all-around riding and a 25mm Ksyrium Pro Carbon SL-C for climbing.
I had the opportunity to ride these wheels for a couple of days. While I normally like to ride a wheelset 500-1000 miles before reviewing them, I got a good start on figuring out the character of this wheelset with the time I had and the range of conditions under which I was able to ride it.
The first ride was on a beautiful fall day covering 122 miles (196km) and 8802 feet (2682 meters) of elevation on a range of road surfaces from new, smooth pavement to packed dirt and gravel with the typical range of good to cracked but all paved road surfaces most of the ride. The climbing included a good amount of hills (<5%), moderate climbs (5-7%) and a couple 2 mile long roads to peaks, the first which averaged 12%, the second 8% and both with a few of 15-20% segments. Of course with the distance we rode, much of the riding I did was part of a paceline on flat roads and with plenty of time solo as the group broke up and I found my nose in the wind.
The second day, as luck would have it (at least for testing purposes), I did a short recovery ride in the rain.
Based on this riding experience, I find the Mavic Cosmic Pro Carbon SL to be a strong all-around performer. Its versatility is clear as it handled the range of conditions I described above equally well. The Cosmic’s dry braking is clearly its strongest feature, the performance being almost on par with the ENVE and Zipp NSW textured brake tracks on dry roads and when descending mountain pitches. On wet roads, it was notably inferior to both and more on par with the better non-textured carbon brake tracks like the Zipp Firecrest line.
The $1800/£1670/€1860 suggested retail pricing makes it attractive especially when you consider that other carbon wheelsets with similar braking performance will cost you about 1000 US dollars, Euros or Pounds more.
On the flip side, I find the noisy free-hub to be a real distraction akin to the Chris King hub volume at a slightly lower frequency. My personal preference is for a much quieter free-hub like what you get with the DT Swiss 240 but if you don’t mind or even prefer the “here I am world” sound of a freehub, this might be the wheelset for you.
Overall, the Mavic Cosmic Pro Carbon SL clincher has a very solid feel. It is stiff when powering forward or uphill and handles and grips well on the 25C Yksion Pro tires that are sold with the wheels.
I normally test all wheels on known, low rolling resistance Continental Grand Prix 4000S II but since Mavic claims the wheels and tires are a “system” and you have to buy the tires along with the wheels, I rode them this with the tires provided. They ride comfortably on all surfaces. The tires measure 25.5mm inflated at the 85psi pressure I rode them at and about 26.0mm at my benchmark 100psi. This is nearly the same width as the 25.6mm external rim width I measured halfway up the brake track and 25.8mm at the widest point, slightly diminishing their aero performance. Ideally, you want the rim width to be about 1mm wider or more than the mounted, inflated tire width so that the wind coming off the tires will re-attach to the rims with the least amount of turbulence.
Of course, I can’t test the aero performance in a wind tunnel but on the road, they feel fast but not as fast as the Zipp 303 Firecrest or Easton EC 90 SL also reviewed in my all-around post that I linked you to at the top. I don’t know how much of their relative speed is due to this rim/tire width difference, the rim’s U-shaped aero design (usually a plus), the rolling resistance of the Yksion tires (not slick), the friction in the hub or something else.
They roll smoothly and maintain forward momentum well once getting up to aero speeds of over 18-20mph (29-32kph). They also accelerate well but nothing out of the ordinary. As mentioned above, they felt solid climbing, if not any lighter than other all-around wheelsets. Their measured weight of 1574 grams (well over the claimed 1450g weight) puts them at the high end of the range of wheelsets in this all-around category.
A few additional comments on braking. While I put more value on the going fast performance characteristics of wheels than the slowing down ones, several carbon wheels in this review either don’t do well slowing or shriek so much when they do or both. Those are deal breakers for me. Others do just fine slowing and do so quietly but don’t slow you as quickly as alloy wheels on dry roads, less quickly still on wet, and you’ve got to adopt alternate front/back braking techniques going downhill so you don’t warp them.
The latest ENVE and Zipp NSW carbon wheelsets are just as good as wheels with alloy brake tracks in the dry and wet (ENVE) and just a bit off the pace in wet (Zipp NSW) while being quiet throughout. You can almost drag them like you do alloy wheels though I wouldn’t “poke the bear” and tempt fate. I do it for the sake of you, my fellow road cycling enthusiast, and only after making sure my life insurance is paid up.
I’d put the Mavic Cosmic Pro Carbon SL in the mix with the ENVE and Zipp NSW in terms of dry braking performance. I alternated the front-rear braking going down the steepest of hills (10-15%) and dragged them going down the slight less pitched ones (7.5-10%). No heat build up, great performance in both situations though some shrieking after a while when dragging.
In the wet conditions, I found they were really no better than other non-textured tracks. They will slow and they will stop, but you might use up all your fingers on one hand counting the seconds before they do. I’ve read other reviewers say their experience was as good on wet roads as on dry ones. That was clearly not what I found.
The Mavic brake track is what I would call “roughened” rather than textured like the ENVE or scalloped like the NSW. Perhaps Mavic’s doesn’t provide any place for the water to escape. I’m also not wild about the Swiss Stop Yellow brake pads that come with these wheels and that you must use in order to prevent voiding the wheels’ warranty. Besides leaving a yellow film on the rims, I’ve found they are more likely to squeal than other pads I’ve used on multiple carbon rims.
It’s good to see Mavic is in the all-carbon wheelset game now and, depending on the characteristics you value most, offering a well-priced option. The Mavic Cosmic Pro SL clincher aka SL-C is available at Competitive Cyclist, UK/EU Tredz 10% discount with code ITK10, Chain Reaction, Wiggle, stores with the best prices on this wheelset and high customer satisfaction ratings.
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