Originally Posted by rpenmanparker

But if the increased area is inside the jersey and not exposed to the airflow, how does it function? If the moisture still has to be transferred to the outside of the jersey to evaporate, how does base layer surface area make any difference? And if the jersey is good enough at wicking sweat from the base layer to the outside, why isn't it good enough at wicking it from the skin?

Originally Posted by rpenmanparker

As for summer base layers being too lightweight to insulate, it is the air pockets, not the weight of the fabric that provide the most effective insulation. You see that with "thermal" blankets all the time. They are very lightweight and are made to be used alone on warm nights and under another layer on colder nights. The air pockets trap air between the sheet and the top layer to provide the insulation. It sure looks like mesh base layers would work exactly the same way. I'm not saying that is what is actually happening with them, but it seems natural to apply a standard way of looking at things to this discussion.