Originally Posted by
colnago62
I have always felt that a base layer holds your sweat closer to your body which helps regulate cooling. You do see a lot of riders who do not use a base layer when it’s hot. I wonder if it doesn’t make a difference.
It was either a podcast with the lead technologist from Pearl Izumi or a VeloNews tech podcast where the point was made that most cooling comes from sweat evaporation due to the large energy required to evaporate water. Therefore, having water evaporate as close to the skin as possible rather than clothing is best. A base layer transports water from the body to the outer jersey layer and so reduces cooling. That’s good in cold weather, bad in hot.