Hi all - I've been trying to get in shape lately, but I keep getting stuck with a shin splint from the running route so thought I might be better off with a bike or at least having one so I can switch things up and cross train a bit. My question is though - is it a bad idea to buy a mountain bike if I only want to take it on trails occasionally? I would probably ride it on the streets for exercise most mornings. Also I'd like to ride with my dad, who is an avid road biker and generally goes for two-three hour rides. Will it be hard for me to keep up on a mountain bike (other than the fact that I am probably just slow to begin with)? Basically my question is whether it is a dumb idea to buy a mountain bike if I am primarily going to ride it just for exercise purposes on the street.