Is it worth it? I don't mean thermal layers like what you'd wear in the colder months, but a lightweight breathable moisture wicking layer. Practically all my jerseys have moisture wicking capabilities, in some degree, but I'm wondering if it is beneficial to have an extra layer when the humidity skyrockets.

i wear casteli sleeveless mesh during socal summer. when i open my jersey zipper, air feels cool on the mesh.

why should we wear base layers in the summer? i never quite understood why we pay 200 dollars for a jersey just to put a base layer underneath.

I have always worn a base layer. I don't like bib straps on bare skin for one thing. The other is if you fall, it is far better to have a base layer on. I have some light wool base layers that I've been wearing this year. I also use polypro, seems to work just as well.

I have a fancy mesh castelli one that I wear on long rides, but 90% of the time, I don't bother.

A summer base layer top is thinner, flows more air than the average jersey and is skin tight unlike most jerseys. It keeps your $200 jersey from getting soaking wet and your skin hot and clammy. Now, if you're paying $200 for a jersey then that's your fault.

if the jersey is loose fitting, how will the sweat evaporate from the base layer? doesnt it need air flow to dry?

I wasn't a summer base layer person until last year. I have some sleeveless mesh baselayers and they actually work pretty well, i.e. I feel cooler wearing a baselayer than not wearing one.

I mostly use the Craft sleeveless base layers, but do have a couple of similar Specialized ones.

The base layer isn't really supposed to be dry. It transfers moisture from your skin and soaks it up. Works sort of like evaporate air conditioning systems houses in the desert have. It soaks up your sweat and the air flowing through gets cooled by the moisture so your skin gets cooler. All you really need to know is you will feel cooler and your core body temp will be lower if you wear a baselayer. If you're looking for even more scientific stuff I can't help you.

Which is great....if the dewpoint isn't so skyhigh that the sweat in your baselayer actually evaporates, and doesn't just become yet another sopping wet rag on your body for you to stew in.

Not in Houston. Evaporative cooling kind of fails in our humidity. Less clothing, the better

I don't know why, but it works for me. Protection from the bib straps is a significant plus. Easy enough to try one and see if you like it.

What are bib straps? That is another garment feature better left out of the Houston summer cycling wardrobe. The fewer layers, the better. But I already said that.

I feel your pain! Fortunately I don't have to live in Houston.

It still wicks sweat away from your skin. It works and I live with higher humidity than you. We started wearing Under Armor baselayer tops in the army on misson in serious heat with ACU's and full body armor on. We managed to get our unit to buy them for all the boys. Much better than having a soaking wet t-shirt.

Doesn't hurt to try it.

Initial purchase a couple of summers ago, was a Nalini sleeveless.
Fit was ok, but way too long.

That recently wore out, so I purchased an Assos summer sleeveless from the same shop.
Way better fit/length, but more thicker than the Nalini. But I love it.

Assos has 3? sleeveless models, depending on the season.

I suppose the main reason I wear them is to keep the sunburn away.
Although my summer jerseys are rated UV?50, I need all the protection I can get, due to my light skin, and riding in up to 45 degree summer temps.

Do you actually burn under a non-UV protective garment?

Just this year, I too have begun to wear a Castelli sleeveless mesh base layer during the Norcal summer.
When I open my jersey zipper, the air feels cool on the mesh.

It is like a car radiator grill, and cools me down way faster than bare skin.

Bib straps get tucked inside the waistband. Presto ... shorts !
And no base layer either. Maybe a base layer makes sense somewhere, but the fewer layers the better here when it's hot.

Can you explain the difference? I understand that the jersey protects your skin from the direct solar rays. But otherwise it seems like what you want is to get sweat from the skin to the outside of the jersey where air flow will evaporate it. It seems like making the sweat go through the base layer, transfer to and through the jersey, and then evaporate is just going to slow down the evaporation, compared to just wearing a jersey that wicks moisture as well as the base layer material.

A baselayer top is not a heat insulator. It's not going to make you hotter.

Never used to wear a base layer, now wouldn't consider without.. bib straps one reason, but generally just more comfortable. Columbia "Quickest Wick" base tops are great for the price.. eg.
Columbia Sportswear Quickest Wick Base Layer Top - Sleeveless (For Men)

That is just plain wrong. In drier climates the surface evaporation efficiency may trump the heat insulation, but not in a humid climate.

That's a pretty good price, especially when compared to other cycling specific apparel. Thanks for the link!