Fit and function is just right. I wear this under my cycling jersey most morning rides. It doesn't add a lot of warmth, you can really feel the wind coming into the sleeves. Just enough to take the edge off on the warm up and not too hot for the interval rides. I wear it in the mid 50's with jersey and vest or no vest depending on high or low 50's. The build quality and stitching looks to me like it'll hold up well. I've worn/washed maybe 30 times and it's still as good as new.
When the heat index is between 90-100 degrees you may not think of adding another layer until you try this base layer. Then you look for it each and every hot weather ride. This micro thin layer absorbs sweat and then the convection cooling that keeps your core temperature down is enhanced. I now have two of them even though they quickly dry after hand washing to get the salt off. I also bought them for my hiking wife. I am 5 feet nine inches tall and between 160 pounds. A medium size fits just
fine.
If, like me, you aren't waiting for the "perfect" weather to ride you'll be surprised to find yourself ordering this 'base layer' again after using it on a 90-degree day. This base layer is a micro thin sweat wicking layer that allows your body to keep your core temperature lower. While it doesn't replace drinking massive amounts of fluid when the heat index is over a hundred degrees every little bit helps. I am 5'9' inches , 164 pounds and wear medium. My 5' 1"' wife who hikes a lot has two in size small. If you ride frequently having a second set is nice though I have hand washed mine and they dry almost instantly.
I've ridden these a lot on rides where the temp goes well over 100'. Keeps you cooler than just a jersey, that's for sure. You wouldn't think they would but they do. You don't even notice that it's there except that you're cooler than without it. If I had to make a complaint, it's that sunscreen stains the neck after a while. But nobody ever sees these when you're riding so who cares, right? They go on sale every so often so keep an eye out.
