I don't know much about Texas, but 70 degrees isn't all that hot in Florida. 20+ years of living here has thinned my once-hardy Yankee blood to the point that I'm a weather wimp, and at 70 degrees, you'll find me still cycling in my knickers and maybe a thin long-sleeve top. I like this one from L. L. Bean: Fitness Tee It's very lightweight cotton, treated to have wicking properties, and with a nice zip-neck. If I get hot mid-ride, I just scrunch the sleeves up above my elbows. I find that my legs are still comfy in knickers up to about 75 degrees, depending on humidity.