Are any of you guys in the heat other than when you're on the bike? If not that could be part of your problem. Its been over 100 degrees 37 days so far this summer here and we're all still riding. Our tuesday evening group ride happens at 6:00 and its still well over 100 then. The other thing that you should pay attention to is your diet. Eating a crappy diet is an easy way to feel like trash in the heat.