Originally Posted by dutret
Think about forward pedaling. People who spin out while climbing [in dirt] almost always do it in the middle of the pedal stroke and then regain traction when the pedals reach the top and bottom.
This is exactly what Kirk said and I was said by a controled spin. You have to know where your pedal stroke is and what you can do with it at all 360 degrees of rotation. Just like experienced dirt riders have learned to keep from braking traction at 3 and 9 o'clock climbing hills, fixed geared riders...even those that ride on the street have learned that by varying the spin you can have as great of an effect on decelerating, if not better, then if you had a rear brake. By using a rear brake and your legs you are taking away the ability to really control the rear wheel with your legs.
And yes some brakes do have a higher tendency to not allow modulation then others whether U, V, mech, or hydralic, etc....