In my opinion I think that as long as you have common sense you can start off on any bike you want, not counting the money issue. My suggestion is to go sit on all of the different bikes that you think look good and then ask yourself, is this the riding position that I want, can I put both of my feet flat on the ground with the bike stood up, am I strong enough to not drop this 500 + pound Hyabusa at the stop light? Once you find the bike that is for you go ride it! But don't be an idiot and go out and see how fast it can go the first day you have it. almost every sport bike I've ever ridden has about the same amount of acceleration from 1000-6000rpm's so there you go. Get that GSXR 1000 but learn how to ride before you go dipping into the power band! Everyone knows what thier limit is, and I don't see why an ex250 is a good starter bike when you'll want a bike with a real suspension and a real motor and real brakes and tires in less than 6months. This seems to me like a big waste of money. So once again this is my opinion, and it is get the bike you want now, not some rinky dink toy, take a slow learning curve and be safe. If you feel like you still should get an 250-500cc bike go take the MSF beginner course they give you a 250 to learn on and you will out grow it by the end of the 3 day class. not to knock small bikes I have an ex500 but does it compare to a proper sport bike in the twisties NO! But is it a hell of a lot more comfortable compared to my GSXR, and fun to ride around town? You Bet!