I REALLY worry about pitching over the top of my handlebars. Seems to me like riding a fixie would have a lot more opportunities for that to happen one way or another. My commute route is pretty flat, just an extended bump or two in the way of 'hills'. It feels so exciting looking for a new kind of bike to ride and yet so terrifying. Just saw a beautiful one with rear brakes in neon yellow and green. Fantastic stuff.