Looking for advice with an ongoing nagging issue. Seems after I hit the 40 - 50 mile mark, my hammies start to cramp up. Yesterday I did a 70 mile cookie ride and had to stop and walk every mile the last 10 miles, to stretch my legs. I'm drinking plenty of fluids (gatorade), taking GU and cliff bar, and have even tried salt tablets. It's becoming frustrating because I'm moving at a pretty good clip and then WHAM!, the muscles start to cramp.