This is probably the same old question but here we go anyways. I have never riden a dirt bike before but i am going to get into it. I was wondering what everyone thought. I like to go fast. I will mainly be riding in the desert and trails but i live 15 minutes away from the dunes so i will probably be hitting them every once in a while. I want to buy a bike that I am not going to grow out of so i was wondering if i should just get the 450 or stick with buying the 250. Keep in mind i am a fat dude (6' 215). Is a 450 going to be to hard to learn on?