Originally Posted by
vaticdart
Yes, it's a pipe dream.
No fabric exists, as of yet, that is breathable enough to be truly waterproof and provide enough ventilation for the kind of sweat one produces on a bicycle while keeping a good pace. I have an Endura waterproof cycling jacket that does decently, but I can only wear it, even with just a lightweight athletic T on underneath, when the temperature gets decently below 40 degrees F. The eVent stuff is supposed to be more breathable and that might be true, but I doubt they're breathable enough.
I sort of agree with you in that nothing will be truly waterproof, but how about a jacket with eVent front, back, shoulders and outer arms, and open mesh everywhere else? It would do in a bit of rain and the open mesh would allow air to freely move. Sure water would get in, but it would avoid getting soaked right away...