I don't know about the shoes, but it could be your saddle placement. Have you been fitted by someone who was aware of your cramps? You might try moving it back a bit (and also down a bit, to preserve the distance from your pedals). Someone advised me to set my saddle way forward, when it turned out that my problem was really that it was the wrong shape. It just gave me terrible cramps not only in the calves but in the tibiales anterior, too.
And, when you say "electrolytes," are you including magnesium? That's almost always the culprit when I get cramps.
Not to say it couldn't be the shoes, too, I'm just not aware of that being a problem, at least not with stiff cycling shoes.