"It's counter-intuitive, but a well made base layer is cooler in the heat despite the extra layer."

Maybe it is, umd - for you.

Even if true, though, "cooler" is a relative term. How much cooler? Enough to make a difference is sensation, in performance, etc?

As for full-zip jersey's they're great. But they aren't so easy to find – I have just one out of the many jersey's I own – and they are often more expensive because of that very feature. Yes, they would be cooler on a hot ride; but again, "cooler" is a relative thing. Somehow I manage to survive on 3/4 and even 1/3 zippers.

And I'm not ruling out that spending $50 on an base layer doesn't lead to some confirmation bias on the part of the purchaser.

Without hard evidence, all we are left with is anecdotes. For you and Botto and others, a base layer works in the heat. For me, it doesn't. I'd like to see some scientifically tested results of what does happen to the human body in and out of a base layer. Then I might find out that the one with confirmation bias is me!


(For now, if the guys below don't need a base layer, neither do I.)