Originally Posted by BoraxKid

I've spotted plenty of pros wearing summer base layers under their jerseys at both the tours of France and Spain. That's actually how I discovered summer base layers in the first place: I saw a pro giving a post-ride interview at the Tour de France with his jersey open, and I noticed he was wearing some kind of mesh layer under his jersey. Then I heard the GCN boys mention the importance of a good base layer and how it can help cool you down, and they're pretty much all ex-pros. One of them even rode for the Rapha test team, I believe.