My dad is 57, and he wants to start mountain biking with my brother and I. He is very physically fit. Strength trains and runs/walks at his gym five times a week. Even so, he is still 57. I was wondering if you think a hardtail would be too hard on his back. He hasn't ridden a bike in forty years. I just dont want his body taking too much of a beating and keeping him from really enjoying the sport. He is picking up the sport to spend more time outdoors and the cardio. No jumping or hardcore stuff. Also, he is wanting to spend a max of $500. Any suggestions from some of you on bikes you have had good experiences with would be wonderful.