Some pedal systems such as SPD couple the concepts of float, release angles and tension. They use tension to determine engagement. Other pedals such as Time ATACs, Speedplays and Crank Brothers decouple these concepts and treat them seperately. On my Time ATACs, I select release angle by positioning of the cleat much like the Crank Brothers system (actually Crank Bros. borrowed this idea from Time) and I have free float of +/- 5 deg angular and +/- 3mm lateral (side-to-side) before I start hitting spring tension. The tension is effective at that point until I hit the release angle. The tension in my pedals is not adjustable although the springs can be changed to change the feel. The newer Time ATACs work in the same manner but have an adjustable spring setting that allows the user to determine how much threshold tension there is beyond the allocated float range. The release angle and float are still independent of the tension. My roadbike pedals (Speedplay Zeros) allows me to independently adjust inboard and outboard the float range as well. This also does not effect release angle or spring tension. A decoupled system like this is generally regarded as superior because it doesn't force you into a compromising disengagement thresholds for leg positioning and ride comfort or vice versa. This is especially important in say mountain biking where you may want to have the ability to move the bike around you without accidently disengaging. This is also important for people who have knee problems and require free-float.