21 Jul Corima MCC 47mm S+ Aero Wheelset
Corima MCC 47mm S+ Tubular Aero Wheelset
If you’re looking for the very best in bicycle wheels and are considering Corima MCC 47mm S+’s you have arrived at the top end of bicycle wheels and at this stratified altitude there are only a few possibilities;
Lightweight, the German carbon wizards with their all purpose Meilensteins.
Reynolds, the innovative Americans with their carbon RZR wheels
Mavic and their ‘Lightweight rip-off’s’ Ultimates
Corima, the little known French wheel specialists that make some very interesting high end wheels.
At this £2000+ price level, you are looking for; very low weight, good aero performance, top end bearings and a certain ‘bling’ factor! All the above wheels deliver in these areas, but some more than others. It makes sense to go tubular at this level as your wheel will be much lighter, safer with none of the drawbacks of clinchers. Here we will look at and thoroughly road test the Corima MCC 47mm S+ wheels.
Corima, like the others, uses a full carbon construction; rim, spokes and hubs. Where they differ from the others is that they use a small number of thicker, stronger, bonded spokes that are not in tension. They simply depend on their stiffness to keep the wheel true. This means that although you have far fewer spokes, (12 in each wheel (Lightweight is 16 and 20)) they are much more substantial, and for this, read, less aero.
Corima modified these wheels in 2015 to make the front spokes bladed as opposed to round. But the rear still has round spokes. Here are the details as regards spoke dimensions;
Spoke Dimension Data
Corima front wheel = 3.2mm thick bladed spoke x 24cm x 12 = 92.16cm2
Corima rear wheel = 4.8mm thick round spoke x 24cm x 12 = 138.24cm2
TOTAL = 230.4cm2
LW front wheel = 2.2mm thick bladed spoke x 24cm x 16 = 84.48cm2
LW rear wheel = 2.2mm thick bladed spoke x 24 x 20 = 105.6cm2
TOTAL = 190.08cm2
As you can see, even though the Corima has far fewer spokes than the Lightweights, they present a much larger surface area, which is important when the wheel is spinning fast. Also, a circular shape has a worse Cd (aero performance) than a bladed or teardrop shape. Many magazine aero tests simply place the wheels in a wind tunnel and measure drag. But what they are NOT measuring is how much power it takes to actually spin the wheels. This is power that comes from the rider, and the more aero your spokes the better. A little test you can do at home is to put your bike in a stand and spin up the rear wheel as fast as you can in a big gear. You can feel the air turbulence around the wheel, like a fan. This is for the most part due to the spokes cutting through and disturbing the air – the rim and the tyre have no ‘attack’ point, they simply have some minimal surface boundary effect. Thus, the deeper the rim the better, not only for smoothing airflow around the wheel, but also to reduce the amount of spoke area.
The Corimas weigh 1143g which is only 20g or so more than Lightweights and comparable with Mavic Ultimates. They have a wider rim than either the Lightweights or the Mavics, meaning that trendy 25mm tyres fit a bit better. The nose profile is blunted and rounded, which is more ‘a la mode’ than the other two. In theory this should help in sidewinds.
So how do they ride? Fitted with Vittoria CX 23mm’s pumped up to 100psi (about 7 bar), (our standard setup for all tubular wheels) first impressions are that they feel very stiff. Indeed, a French magazine recently tested them as being stiffer than any other wheel out there, see here. This translates to a crisp, powerful ride. Every watt of effort that goes in come out unscathed, propelling you forward, faster. You can run your brake pads very close as there is almost no deflection. These wheels would be great for sprinters or explosive riders. The downside is they do transmit the road surface more to the rider. There is very little give or comfort here. Fitting 25mm tyres would no doubt help in this regard.
The bearings are very smooth and the wheels roll well. However, there does seem to be a bit of transmission lash; when you come off the power slightly, the freehub disengages a bit too quickly meaning that there is a bit of clunk. For example, if your pedal stroke is not smooth (like when exhausted at the end of the Etape du Tour!) you may well come off the power enough at the top of your stroke to disengage the freewheel and get a clunk. Less than perfect gear changes also are punished with a bit of lash. The other wheels we have tested do not have this ‘feature’!
Crosswind stability is good but not class leading – we found the Lightweights and the Mavic CCU’s (which aren’t as deep) to be a touch better. In any case, it has be blowing pretty hard for this to be a problem.
Bling factor?! Well, yes in spades! The lack of spokes makes for a truly unique looking wheelset that always draws attention. The graphics are bold and brash too, perhaps too much so?
So to summarize, an excellent high end wheelset, in the Premier League for weight, and absolute top of the class for stiffness. But with small compromises in aero performance and ride quality. These wheels would be a great choice for something like the Etape du Tour – good roads, lots of climbing and relatively low average speed.