IanB should chime in here. Just sitting on his ST13 and my ST11, the ST13 feels a bit more top heavy. Don't know why that should be as the ST13 is lighter, and has quicker steering geometry. The ST13 has better brakes and the adjustable screen if you have the right model. But then I have only ridden the test bike at the Snowy Ride, and they are always faster :)