The first sag was 25 miles, ate a whole banana, 1 hard boiled egg, a few crackers & cheese, a couple apple slices and a piece of bagel with peanut butter. Hmmm.......maybe I overate?

Well, looks like lots of possibilities. After reading the replies, I now believe the cramping is related to inadequate fitness. I just haven't ridden enough this year or put in enough hard rides in. It's strange though, since I wasn't pushing or riding hard. Never felt like I was winded or hurting before the cramps set in. It was a real bummer, realizing I needed to ride slow to even finish.

Thanks all for the replies, much appreciated.