One time when i got a flat close to a friend's house but not close to a bike shop, I borrowed my friend's girlfriend's bike which was a SS rather than fixed. Since i had not ridden a non-fixed bike in 2 years or so it was very disconcerting not to feel the pedal force its way up. However, I didn't experience the feeling when i was spinning, it was only when i was, say, coming to an intersection and normally am applying minimal back pressure except that with the SS the freewheel was spinning and my feet stayed basically still. But when i descended or spun or whatever, i noticed no problems... maybe this was a misdiagnosis of the sensation