The biggest question regarding braking in dual suspension bikes is whether or not 4-bars rear-brake better then mono-pivots.
There is a very well established myth (well-propagated by the magazines) that mono-pivot shocks will lock under rear braking. This is known as “Brake Induced Shock Lockout” or BISL. We have demonstrated this to be false.
We have also demonstrated through experiment that mono-pivots do not significantly extend or compress under braking.
We have even demonstrated that certain 4-bar designs, such as the Jamis Dakars and the Psycle Werks Wild Hare, should brake almost exactly the same as a mono-pivot with identical main pivot location. We have seen many "Dakar and Wild Hare reviews" from Mountain Bike Action, Bicycling, and several other industry magazines. That none of the reviews mentions BISL in these 4-bar designs is a good indication that it does not actually exist.
Most 4-bars extend from natural sag under smooth-surface braking a bit more then equivalently main pivoted mono-pivots, establishing a new equilibrium position and rate. Some, such as the Yeti AS-R, compress under smooth-surface braking relative to equivalently main pivoted mono-pivots. In addition, changing frame geometry through travel, due for example to bump compression, may cause the braking effect to change, further altering the effective suspension rate of a 4-bar.
But again, none of this leads to the conclusion that 4-bars brake better then mono-pivots in general, since a mono-pivot could well have (and some probably do) the same rate under both braking and pedaling as most 4-bars under braking.
The biggest consideration is the relation of the rider's body mass to the wheels and what it will do under braking. This author believes that between most of the designs, the differences are just not enough to merit a general statement.
Some people find 4-bars to brake better, but others do not, though we have seen no double-blind tests. In the end, the small differences between some designs may be significant enough for some people to feel a difference. But in general, we suspect that this is again just a case of the very well established psychosomatic phenomenon. This would not be the first time that people have been told that something is so and many have experienced what they expect (this is why placebos cure illness). Or perhaps it is again a little of both.
We also have no doubt that the BISL myth has been propagated by some in the interest of selling more expensive 4-bar designs. We see no $ 2,000 mono-pivots.
In the near future, we hope to do a double-blind experiment to see once and for all if there is a difference between 4-bars and mono-pivots, under braking. We will publish any results in subsequent editions of this work.
In any case, our advice here, as always, is to make your decisions through testing the bikes, if possible.
What we have stated above regarding 4-bar linkages also applies to floating rear brake systems, since a floating brake will give a bike the same rear braking character as a 4-bar with the linkage geometry of the floating brake. Imparting the character of its linkage geometry is the only thing a floating rear brake does, for good or ill. This will, for example, give a typical mono-pivot suspension the tendency to extend under braking, rather then its inherently neutral character.