I am 18 and live in Nashville suburbs but fairly close to the city. I have a car but it is broken and I am facing the fact that I will never be able to fix it. I live with parents and live a 3 mile hilly walk from the closest bus stop,.... which carries bikes to the next location. Everyday I walk the 3 miles home from the stop after school and I am really sick of the extra 30 to 60 minutes is adds to my day, I used to be an avid biker when I was really young and still own the bulky kids mountain bike and when I've gotten it out recently I tire quickly on it and I am wondering if it is the old tiny bike that is almost heavier than me or just me. I thought it was just me for awhile but the fact that I can carry my books for 3 miles everyday without tiring, walk everywhere, and last long after kids in chain gangs in mosh pits is making me think maybe it is the bike. I am looking into buying a road bike or a hybrid to add more time to my day and help me have a mode of transportation besides the bus when I leave my house for good.... which I am hoping is soon. I just don't want to put in the money only to have the same result on that bike too. Help me out here. I need to know if I should go for another bike... I know I need more exercise but I do not believe I am so unfit that I can't go a couple miles without being about to collapse on a bike... would a road bike help me out? Remember that I am 100 pounds and my bike at the moment is 80 pounds. I also would like to know what type of bike I should get and if getting one at a thrift store and having that fixed up would work just as well as a new one. thank you.