Originally Posted by
prathmann
This has nothing to do with reaction times. The basic physics of bicycle geometry limits your maximum deceleration based on where your center-of-gravity is relative to the contact patch of your front tire. Fat bikes may be a bit better than typical road bikes, but unless you can first move your weight back from the normal position your maximum deceleration is limited by the tendency of the rear of the bike to lift and eventually toss you over the bars. OTOH, a car's deceleration is just limited by the coefficient of friction between the tires and road.
This has quite a bit to do with reaction times - the faster you can shift your weight and thus your center of gravity to the rear, the more leverage is required to move your center of gravity over the pivot point and thus the faster you can stop. You can do this while decelerating in anticipation of a panic stop, which is what the poster to which you responded was alluding to.