I seemed to fatigue/cramp in my hamstrings during a long ride (70+). I'm drinking plenty of water/sports drink so I don't think hydration is the issue. My seat position is a bit back from the "ideal" position as determined by plum-bobbing from just below my kneecap to the spindle of the pedal - I do a lot of climbing and this seems to give me a better position for climbing power. Anyway, with the seat back a bit I do seem to accentuate the hamstring part of the pedal stroke. Has anyone experienced or heard of a sore hamstring issue associated with the seat being positioned to far back?