I'm having a problem with my calf cramping up: When I stop, I prefer to just put my left leg down and prop myself up by by tip toes (my butt stays on the saddle). I find that it is easier to take off from this position than unseating myself and putting my whole foot down.

For some reason, whenever I do this now, my left calf muscle starts to immediately cramp up. Is there a particular exercise I can do to prevent this from happening?

Thanks for any suggestions...