OK - I'm a weekend warrior but in excellent general shape and have much more muscle mass than avg cyclist - I had the worst cramping of my life on a humid day in August (think TX) where I had a couple cups of coffee (along with plenty of water). Didn't ride that far when terrible cramps hit (around mile 25) and my other dudes that I always hang with were fine. I got some Endurance caps from Hammer nutrition and it never happened again, coffee or not. I doubt mine was dehydration cause I drink tons of water and ride in heat without problems all summer. The caps were $20 and will last me a year - cheap investment. My brother (genes and looks/build very similar) also cramped bad in spite of everything he tried - except one thing an old retired physician told him - he drinks a small (8oz) of tonic water (w/quinine) about an hour before running and he has never cramped again. E Caps are easier to transport and don't taste as bad as tonic water.