Originally Posted by
mrvile
To all of those who thing riding fixed will improve your pedal stroke, I have to disagree. A fixed drivetrain actually hides many imperfections in the pedal stroke because the momentum of the wheel will keep the cranks going, whether you're putting power down or not. And when you start to really do work, it gets hard to tell when you're moving the cranks or when the wheel is doing it. So what seems like a smooth pedal stroke on a fixed drivetrain may not be. The only thing riding fixed is good for regarding spin technique is that it will force you to really move your legs once the speed leaves your comfort zone, and you'll know when you start bouncing all over the saddle trying to maintain 35mph @ 75GI.
I personally think that the best way to improve your stroke is to just gear down and spin. Keep your butt still. The rest will come over time.
The only time that the wheel will be moving your cranks is when you stop putting any force on them. You will be aware of this because of the unusual sensation of the pedal pushing on your shoes instead of the other way around. Similarly you will be aware when you are coasting on a freewheel because you hear that clicking noise. During normal riding, there is no difference in how the force is applied.