Agree with the theme of the posts above (you'll probably be just fine with the Bonnie) but if you have the time and the resources, you can't go wrong with starting smaller. I started with a 250 v-star, and then a yamaha 650, and then the America..... Only did about 300 miles on the 250, and got rocked by the wind, but it's also a great first bike to learn to throw around, and its harder to make mistakes on it if you mis-handle the throttle or do other things that can occur when you are first learning. My wife and I bought a used virago (v-star) 250 and sold it three months later for the same price, all on Craig's list. Maybe I didn't need it, but it helped increase confidence and build experience while moving up. Since the 650 my wife moved to a vulcan 900 and now an HD Softail deluxe, and I love the America. But I appreciate the 1000 or so miles I did on the 250 and 650 to get here...
Ernie
