The worst experience of cramping I had was probably due to dehydration. But the cramping I'm more concerned about now is the knotting up of my quads which happens in the final (steepest) kilometers of a 42 km climb (around 3 hours riding). It's been interesting reading this thread because if, as CFB would say, the cramps are due to overuse, then endurolytes won't solve the problem. I just managed to obtain endurolytes yesterday and am planning to use them on this ride in 9 days time. I was looking at the bottle of capsules with great expectation!