I just got my Polar A5 heart rate monitor and Im having some difficulty setting the low and high range. I put in all the info, body weight 170, height 5'10 and age 31. It calculated that my range is 123 - 160. Well when I ride, I find myself going over 160 without any real difficulty. I right everyday so Im thinking that my cardio is in fine shape, so what needs to be adjusted if anything. I feel as though to keep in the range its at now, I need to really scale back, especially on climbs - which takes me right up to 170/180? Whats the deal?