Hey you have my exact same duathlon cramping problem! try 2xu compression tights or compressport calf guards, try stretching much more before the race, try increasing your cadence at low effort 1min before dismount, make sure your diet is ok, also make sure you haven’t taken on too much nutritionally…you should only need one lucozade sport on your duathlon assuming you emptied your innards prior to the race and were fully carbed up and hydrated beforehand. Or just go a little bit slower or practice a little bit more!! Good luck with number 2.
via Journey to 5150