On Monday I went to see a bike race in SF. Afterwards I went against the wind as hard as I could for about 2 miles... a single-speed mind you. Turned around and had a sweet tail wind. Then a car, then a curb, now a new wheel set. Just be careful.
I've rear ended cars in the city because I have slicks on my bike. Stopping isn't exactly the high point for the thing, and drivers are ******** (Neither driver noticed... I think). Again, be careful.