This is my first post. I am new to biking and currently own a Trek 820 mountain bike. Long story short I started running about two years ago and have lost 100lbs and I was recently told by my doctor that I needed to slow down on my running because my ankle was showing signs of stress in the the bone. I was told to start biking. My Trek is about 7 years old. I only have around an hour each morning to get a good cardio workout with the bike and I had a couple of bikers tell me that a Mountain bike will give me a better workout than a hybrid or road bike. I bike on the road and up and down hills and want the best cardio workout I can get so I thought I would ask all of you for your inputs on this question. Does a Mountain bike give you a better workout in an hour than a hybrid or road bike?
Thanks for your help.