I have Nokian W106 studded tires front and back, the rear one is a bit bigger...
Im going down a pretty steep slop, and theres a mirror sheet if think ice (and its +3c - +5c).
And im turning (really slow), and a split second later im on the ground.
I fell down so smoothly that i just stayed on the ground cause i wasn't fully aware wtf happened.
I try to get up...uses less, no friction at all... so i slide over to the side of the road and get my feet in to some old snow and pull the bike over, and pretty much walk the bike around this ice patch.
I have pictures of the marks left in the ice, but i cant upload off my phone (vista) atm.
Just saying, there not totally ice proof...