When you guys figure out the definitive, absolute solution, I'll pay you handsomly for the secret. I haven't cramped yet this year, since the weather turned cold last winter, but did cramp a whole lot last year. As with others, about the 40 mile marker. For me, it seems to be related to how hard I ride that first 35-45 miles. If I'm really, really pushing it, I'll tend to cramp in the calfs; only once in the thighs when I put on a massive burst of power in a situation that called for it.

Doesn't seem to be fitness related as I can easily ride a double-metric century. Well, maybe not "easily", but certainly do-able on a weekly basis. Also doubt it is a hydration issue. Might be, but I highly doubt it. Not a nutrition issue either.

I wish I knew for sure, but for the past three-four months, with my daily vitamin/medicine routine, I've been taking a capsule of Potassium and another of Magnesium. Don't think my level of effort has lessened this season. Only once, near the beginning of taking the Potassium and Magnesium did I get a hint of the calfs wanting to cramp up. I backed off for awhile and all was well.

Who really knows what's going on and what's the cause. Nobody knows for sure, and what works for one persone doesn't work for another. Guess it's just one of those life's mysteries.