i am starting to do an exercise bike located in my basement. i did it last yr in the summer and am again starting this summer. i am 15 yrs old, 5 ft 11 inches, and weigh approximatley 150 lbs. how long, should i be on the bike to start out? ( i can adjust the tightness of the pedals either way loose or tight....i think i am oging to start out at 10 min n then increase by 2 min every week or so....but wht time do u think is importnt to me plz n thnk yo 10 pts to whoever answers