Originally Posted by Carbonfiberboy

FAIL!

So I gave the UA Heatgear a try this Sunday on our first 2-pass ride of the year. It was 85° and a light tailwind on the second pass. About halfway up, I realized I was very dehydrated even though I'd been drinking steadily. I took off the soaked longsleeve UA layer and put on my PI sunsleeves and had a much better time from there.

I think what happened is that the heatgear works by making one sweat even more than usual - another layer, right? But if there's a breeze, one feels cooler because more sweat is evaporating. However on a pass climb it doesn't work that way. It just made me sweat more and didn't cool me. I didn't realize how much water I was losing. After I got that thing off, I kept drinking steadily and by the top of the pass my resting HR was down from 120 to 100 and I felt a lot better.

So maybe they're fine for short flat rides, but I'll never wear it again on a serious ride. This one was 75 miles and 5400', which is very short by rando standards. I went through ~90 oz. in 2.5 hrs., which wasn't nearly enough but all I that I had, from wearing that thing.