I'm usually the person to tell people not to go out and get a 250 ninja, however I also don't know if a Kaw 636 is the best first bike, it can be done but make sure you get comfortable on side roads and parking lots before hitting the road. If everything you do on a bike isn't reaction instead of thinking your not safe. With a powerful bike like this you can definately get used to the power quickly with practice but if you get in over your head out in traffic and get nervous and give it too much gas your in a world of trouble. THat also seems a little steep. Not telling you to get something smaller but the Suzuki GS500 is an awesome starter bike and a great stepping stone to a GSXR if you want one down the road. YOu can also pick one up for very cheap, if you get last years model unueed just one that hasnt been sold at a dealership it will probably be around 2900. If you get one a few years old even cheaper.
