The only geared bike I have is a 3-speed, my primary ride is a fixie, and I also sometimes ride a SS MTB with a coaster brake. I definitely run into funny moments when switching back and forth. On the 3-speed, I always have an instant where I want to slow down and forget that I have to use the hand brakes. On both freewheeling bikes, it takes me about 20 minutes before I remember that I can stop pedalling if I want to.