Okay, my friend, but I am not alone here. If you search the internet on this topic, you will see a very even split between our two positions. Here is one example of entries from another forum: Does a Base layer shirt really work in hot tropical weather? - BikeRadar Forum

Unfortunately I can't find any experimental studies, but as you would expect, there are a lot of these kinds of forum posts.

As long as you and I are both happy with what we are doing, that is all that matters.

I think those are fair questions.


Mesh layers wouldn't trap air, what with there being holes all over them. Also, they're probably supposed to be worn really tight.

Now here is another question as a follow up to the recommendations for mesh base layers. I see in the picture posted a short sleeve mesh base layer. A lot of my sweat shows up on my arms and legs. If the base layer acted to help more efficiently evaporate the sweat off your skin by wicking it out to a high surface area on the outside of the layer AND not heat you up by insulation, why not wear a long sleeve one under a short sleeve jersey? Wouldn't that be even better than the short sleeve base layer? Similarly wouldn't folks wear a full leg length mesh base layer on the bottom too? Wouldn't more of it be better? The improvement in cooling could be substantial...if it is real.

Keeping core temps down is more important than the extremities. The head is a great source of evaparative cooling as well and that's why I wear a Sweat Vac or Head Sweat skull cap.

All the same, there is such a thing as arm and leg coolers.
I'm not saying that arm and leg coolers work or that they are worth it but simply pointing out that what you describe exists.

Well there you go.

I don't care what people on the internet say. I don't need to search for google links. There's no way to tell who stretched the truth about their experiences. I physically wear a summer baselayer, I know what it does and Eddy Merckx couldn't tell me otherwise.

Is Eddy Merckx a heat transfer specialist?

Taken on its own, this is really funny.

Ikr?

I tried a UA long sleeve summer baselayer on a pass climb on a hot day. Halfway up the climb, I realized I was getting badly dehydrated even though I was drinking steadily from a Camelbak. I peeled the thing off: it was so wet I almost could wring it out. I drank a good bit while stopped and continued in my unzipped SS jersey with no further problem. Not recommended.

OTOH, I wear sun sleeves on sunny days, mostly to prevent skin damage which they do very well. They are a little warmer than without but the area they cover is small enough not to be a major contributor to overheating or dehydration. I also wear a light poly beanie to prevent sun damage because I'm bald. Again, the area is so small that it doesn't seem to be a negative thing. I don't wear a sun garment on my legs: too much area and sun screen seems to do the job fine there.

I've done long pass climbs in 100+ temps with unzipped SS jersey and sun sleeves just fine.

And, except for shorts, don't wear anything black.

When hot and sunny and riding...
Tops are better than topless.
Base layers are better than no base layer.
And sometimes - long sleeves may be better than sun on arms.

I like white compression long sleeves for summer.