mountain bike all the way. trust me. you gonna want to take this bike out on the trails, jumping things ( pull clutch in for easier ans safer for the motor landings ), running things over, doing the wheelies like a mad man, get the mountain bike. nothing says sweet deal when you are flying down the road at 35mph and do a manual transfer to a trail by drop off right next to the mini van full of kids and a hot soccer mom. i haven't had as much fun on a bike since i was a kid. i have a lot of money wrapped into my bike shop basement ( personal shop, lol) in parts and motors, and gonna do more. once you get into this hobby, it grows like a fungus. slowly taking over. be careful new bike guy, before you know it, you'll have 5 engines sitting on on the build shelves in various forms of coming to life. you'll have jets scattered as far as the eye can see, you'll have NT, RT, CNS, SPEED, and crazy off brand carbs mingling in the file cabinet, you'll have links of chain scattered like peanuts at real western bars, you'll be an addict for making different engines sing a different song. be very careful, and get a mountain bike.