Cuben Fiber Adhesion to Metal

I don't see why it'd be a problem. Just think of it as mylar, because that's what you're actually bonding to.

If the cuben you're using has really thick film, you could roughen it and the metal surface first. I've found that contact cements (like 3M 4693H plastic bonding cement) has good peel strength but lackluster shear on cuben, whereas urethanes like Hysol U09fl have good shear strength but poor peel. What about mechanical fasteners, like rivets?

The mylar would be glued to a mavic cxp-33 aluminum rim. There still has to be enough room left to have a good braking surface.
Who can afford a 1500$ carbon fiber disc wheel anymore?
I had a jdisc as my first disc wheel 25 years ago and loved it. There are some still around, but they are probably all 7-speed. The old mylar on these wheels is not near as nice or strong as the thick cuben. If you can see one pic the the mylar is actually a little floppy. The standard fix was to take a hair dryer and warm the mylar slightly to tighten it up.
A good disc can save significant time over a 40k time trial. I just need something to help me run faster..

So, did the old mylar J-discs have a seam in the mylar? Was it cut so it would form a shallow cone, or just stretched a bit to form the cone? I guess my only concern is that cuben is anisotropic, while mylar alone is (much closer to) isotropic, depending on the degree of biaxial orientation in the film. It might be easier to get the plain mylar tight as a drum with the hair dryer for this reason. Cuben can be shrunk with heat, but not predictably like plain mylar. I've found that cuben wrinkles and deforms in crazy, unexpected ways when it contracts at high temperatures. You might find it very frustrating to get and maintain a smooth, low drag surface with cuben.

Also, on a small scale, cuben has a wavy surface due to the fibers, whereas mylar is very smooth, although this is not likely to make any difference in drag that you could detect.

Colin, thanks for your responses.
I was thinking that the thicker stuff might be stiffer and want to lay flatter. The old discs did not have a seam but were glued to the hub and the rim. I didnt think of the effect that heat may have on the multi-directional nature of the inner fibers. It may not be worth it, but I will probably give it a try anyway after a little more research on adhesives.