What age are you? Try this and see if it helps, get some high dose calcium tablets or chews 500-650mg. As soon as you feel any sign of cramps take two of them. I take two 600mg soft chews and it does wonders, no more cramps. I asked your age because you mention 15 years cycling with no issues. As we get older and remain active our bodies require more calcium. Give it a try it will only cost you one trip to drug store. I've tried all the pickle juice etc but sports Dr. Said take calcium and it worked for me. Good luck!