Originally Posted by
carpediemracing
Wouldn't a wet base layer simply be a net-zero gain of weight? The moisture is from sweating so the body already had it. Even if it's from dumping water on yourself you were carrying the water in the bottle.
Well, the base layer is going to impede evaporation and runoff. If it was going straight to the jersey either it would be evaporating sooner, or the jersey would saturate faster than base layer + jersey, and sweat would start dripping sooner. So, while you did have it in you, once it's not, the base layer keeps it with you longer.