Cosmic Carbone C40: should you buy them?

I have been waiting for a chance to have a look at the new Cosmic C40 since last spring. Mavic seems to have nailed the carbon clincher technology for Joe the average Mamil. A resin with a higher glass transition temperature that does not delaminate upon extensive braking  (can take up to 171°C it says on the sticker) and a carbon rim reinforced with an aluminium alloy bed to withstand higher pressure. They are also light, tipping my scale at exactly the 1540 grams declared by the manufacturer and they don’t need rim tape, as the rim bed is not drilled. Upon handling, the rims appear very stiff, just the kind of rim every builder would love to have available at a reasonable price (heard that Mavic?).

The spokes (275 mm straight pull bladed steel spokes with a 0.9 mm section and 3.2 mm wide) are all the same length, to save the trouble of having to source different lengths for front and rear DS/NDS. They are screwed onto the rim with the well established Mavic technology, whose acronym I can’t recall. They look truly amazing, I have to admit they do and if I was an investment banker with no knowledge of wheel building I would probably just jump on the boat. But I am neither…

The reason they are here is because the guy bought them second hand, hence any warranty claim on a set of wheels worth close to 2,000 pounds is not valid and the usual tedious dealer-Mavic Service Centre procedure does not apply (not for free at least). The front wheel is out of dish and the previous owner must have played with the spokes, as one is slightly bent as a sign of an attempt to true the wheel without using the aero spoke holder. I also need to swap the freehub, which is a straightforward job, involving 1 x 5 mm allen key and a 17 mm cone spanner.

I am not quite sure why the “screw on nipples” appear to have been randomly tightened along the rim, but the wheel is true (except for the easily sorted front dish), the tensions are correct and the vertical offset is near perfect.

Unlike other models, like the R-SYS and SLR, here there are no nonsense carbon spokes, no lethal radial spoking on the drive side and given decent availability of spares (yeah, right… ) everything is easily fixable if you can afford the bill. You can even use after market spokes, like DT aero speed straight pull (275-276 mm), as long as you find the brass washer that fits the thread and the alloy screw on nipple.

So, should you buy these wheels?

I guess Mavic target customer is the wealthy cyclosportive rider, who wants a light and fast carbon wheel, safe to ride down the Galibier and without the hassle of having to carry spare tubulars or silly latex spray. It ticks all these boxes… it also retails in excess of a well specced full carbon bicycle (including wheels) form the likes of Planet X. If money is no object and you are after a set of fast wheels for next year’s Marmotte that trump on looks your mates’ Zipp, then you should definitively buy them.

If you are thinking of buying them for racing, then refrain: they are not the lightest carbon wheels on the market, they are probably not the fastest and they are certainly not low maintenance. You can have a set of 38-50 mm carbon tubulars built on the best hubs money can buy with the best spokes money can buy at a fraction of the cost. The red and yellow stickers are indeed very pretty, but I suppose you can have your own personalised stickers with all sorts of acronyms printed on the highest quality material for probably 40 quid, if that’s what you are after.

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