hamstring pain on right leg

I am a relatively new and inexperienced rider. My husband and I have been training for a tandem ride in El Tour de Tucson in November, my first century! I have been having some pretty painful strain in my right hamstring, particularly when my cadence is high without high resistance or gear. I stretch before and after and I am not finding that I have pain unless I am on the bike (no pain after I am off). I had a really stressful ride on the spinning bike at the gym yesterday. Anyone have any thoughts or pointers? Thanks so much!

January

Check you saddle height or better yet get a fit (a tandem fit would be pretty interesting I would guess) - even a little tiny bit too high can cause this type of pain.