I've done a lot of research on this because I have cramping issues several hours after extremely demanding rides. Screaming on the floor, muscle fluttering cramps. The research says to try potassium, magnesium, calcium, post-ride stretching, and voodoo, but in point of fact the sports-medical world does not know what brings on or cures cramping. There certainly is more than one cause of cramps and more than one kind. Some folks get them while riding, others, after exercise and the symptoms vary. Do some research and learn about the appropriate amount of supplements that can help. I found none of the above to be entirely effective and that's also not uncommon - that nothing really works. Hopefully you'll find something that works for you. I'd try potassium, magnesium and calcium supplements in appropriate amounts to start with.