Originally Posted by
gregf83
But the base layer only gets the moisture halfway. It still has to get through the jersey and it's not clear to me how the extra layer helps that process.
Sweating doesn't cause cooling, it's the evaporation- turning from liquid to gas- that does it.
If the sweat runs onto a loose-fitting jersey, & evaporates there, it cools the jersey, but not as much the skin.
By keeping the evaporation right at the skin, the base layer produces more cooling with less sweat.