maltodextrin
went to the "make your own wine and beer" store, and bought a bag of maltodextrin for about $2.00. i put in in my water (it's totally flavorless) and never have a problem cramping. rode monacrch crest this weekend, my legs felt fine the whole time, and afterward as well. maltodextrin is where it's at.
i assume you all know about this or do it, but in case you are unaware of it, try it out and see if it works for you.