Wicking shirt or bike jersey. I also work outdoors a lot in the summer and find that cheap duofold t's from campmor on sale for under $10 work great. On the bike though I like a bike jersey for the pockets. For long rides I usually carry 2 bottles filled with electroyte drinks, and a light weight hydration pack with plain water. My cellphone goes in the pocket of the hydration pack as I have been known to kill them with my persperation.