Last winter I had this nasty ice patch in front of my house. I flipped the back wheel and put it on fixed. I went over the ice patch clipped in and went down. I then flipped the rear wheel over to freewheel and re-negotiated the same patch while coasting. No fall. I tried using the same speed for both attempts. I was convinced. Sheldon conceded the arguement in his own way. Maybe it just that I have a bad pedal stroke due to a bad left knee.