Would something like what HED do be an idea: ie alu rim with a carbon fairing.
Also don't Flo Wheels do wide aero wheels with an aluminium braking surface? IIRC they performed reasonably well in aero tests and they sell the rims so you can build onto whatever hub you like.
Also don't Flo Wheels do wide aero wheels with an aluminium braking surface? IIRC they performed reasonably well in aero tests and they sell the rims so you can build onto whatever hub you like.