Normally, your road bike frame size is larger than your mountain bike frame. Without seeing it, I'd guess a 17" road bike you found is too small for you. If you post a photo standing over the bike that would help. Getting a road bike that fits you and is adjusted right really makes the difference between a comfortable ride, and pain or cramps after riding a while. You'll help yourself by learning the most about how to choose your size in road bikes and then trying some bikes on the road. It would be nice to get some help from friends with road bikes and visit a bike shop that can let you try some bikes that would be adjusted to fit you best. Good luck!