Originally Posted by
noimagination
I agree with wolfchild. Unless you're riding at a very easy pace, you're going to sweat faster than the breathable fabric will "breathe". For warm weather, just get wet ("technical" fabrics will absorb less water, which has other advantages, but you'll still be wet). For cool/cold weather, focus on blocking the wind to keep the sweat/rain mixture from evaporating and chilling you.
+2. Other than during relatively short commutes, I am usually wearing rain gear when I am touring and thus on the bike for often long periods. If it's cold/cool out and I am working at moderate level or above, I count on my rain gear to keep me warm not warm and dry by the gear "breathing."