Originally Posted by
VegasTriker
If you go to the Gore website they have an explanation about how Goretex works and about breathability of Gore fabrics. Really strenuous exercise can produce enough moisture to overwhelm the ability of the fabric to pass water vapor molecules through it. Then you get wet from the inside.
I have one of the Gore Windstopper neon green visibility active shell jackets. It really works to stop wind from wicking heat away from you. If you ride in a low humidity environment when you do get even a little damp the wind can really be chilling. I use wool sweaters of various thicknesses underneath it as it cools down in winter. I bought mine at a garage sale for a couple of bucks so I have no reason to complain about anything. It was a good buy.
Gore-Tex and other breathable fabrics are nice but they're not magic. Nothing is going to keep you dry if you'd be wet even with bare skin. Likewise, they all require vapor pressure to work -- if the temp inside the jacket is the same as the temp outside the jacket and the relative humidity is 100%, nothing can evaporate.
This stuff is windproof, but if you ride in a low humidity environment, you might be happier with a windbreaker since they're generally lighter, cheaper, and breathe better. But the newest materials can get you a jacket that is as light as a windbreaker, will compress to the size of an orange, and be fully waterproof/windproof.
What works best depends a lot on how you ride. Generally speaking, the lighter your effort, the more things that will work for you.
These materials let vapor rather than water pass through, so they're not nearly as effective when you have sweat directly in contact with the garment. This means that if you use a waterproof breathable layer like Gore-Tex, you really need a base layer of some type for it to work properly. I tend to use a thin technical layer when cycling unless it's really cold in which case I add a thin merino layer. I use that same combination for mountaineering and kayaking.