On the becel ride for heart charity ride that uses closed off freeways, if I want to go faster, I ride the white line, because it's really smooth.
Aside from the above mentioned surfaces, also watch out for leaves after a rain. Wet and slippery, because the tire will grip the leaf, but the leaf won't grip other leaves or the road too well.
one paved surface that does well with knobby tires, is gravel on paved road, which can be found near construction sites. Yeah, I wiped out on gravel on paved road with slicks while taking a slight turn at 20km/h.
Last edited by AEO; 11-22-10 at 08:56 PM.