i have just got into mtbing and triathlons and dual-athlons this year. my question is that when i am at a resting heart rate it is around 48-54 which i think is pretty good. when i get riding my heart rate just goes through the roof it is hard for me to keep it below 175. i think this a little high but not sure at that rate i still fell good but dont understand y it is so high. the reason for asking the buddy i ride with heartrate at resting is in the 60 but when we get riding he is in the 150-155. his max is 163 mine was 187. dont seem right to me just wondering if anyone has some input for me. thanks kyle