a 125cc would be good for you just remember mx bikes are a lot diff. than trail bikes. if you go with a 4 stroke you can put and learn how to ride. mx'ers dont really like to put but in the long run, you can ride them for a long time, and wont outgrow them like you might a smaller trail bike. Honda 230 would be perfect for your height, and the suspension would do you ok until you start hittin the track then you'd have to look for something else to ride. and if your pretty aggressive you might get bored with it kinda fast, and wanna start dumpin a lot of money in it. so i agree go with a 125.