Try Hammer Endurolyte capsules! It might sound like a commercial, but it really has worked for me when sometimes muscle cramps have been debilitating for me. I suffered greatly before trying this.

Also, coconut water is great, and I will drink some prior to a hot workout. Even better, try a bottle of 'elete electrolyte' add-in. You just squirt a little into your water bottle. Both coconut water and the electe product are a bit of an aquired taste, so it doesn't hurt to squirt something more flavorful in as well.

Both products can be bought at Scheel's or probably other large sporting goods stores.

A big difference with both of these is that they include magnesium, which is not often found in other sport drinks. They also have b vitamins that I am guessing help it become easily ingested.

Anyway, I have literally been stranded with muscle cramps while riding, and this has eradicated the problem for me. Best of luck to you