As I've studied more about the bike fitting process, I begin to notice "things" as people ride there bike-especially if I'm riding behind them.  One of these "things" is the knee wobble. 

A common pedaling style that I have noticed is that on the down stroke, the knee will buckle to the inside.  Then, on the upstroke, the knee will go back to "normal".  If you assume that most people ride at approximately 90 revolutions per minute, this is 5,400 times a hour this occurs.  This side-to-side wobble is highly inefficient and can lead to knee problems.The reason this happens is that most people have a slight tilt in the foot.  For most people, there is a small gap on the inside of the foot.  A good way to illustrate this is to stand on one foot and then bend at the knee.  Watch as your knee buckles inwards.  This happens because the floor is flat and there is a gap between the foot and the floor.  As you apply pressure, the foot rolls to meet the flat surface.

 Now, imagine that the floor is your shoe that is locked into a flat surface (your pedal).  Your foot is inside the shoe and as you pedal, your foot is rolling until it makes contact with the bottom of the shoe.  Then, when you begin your upstroke, it's returning to neutral.

The Bike Fit Wedge takes care of the problem.  The wedge fits between the bottom of your shoe and the cleat.  The wedge angles the cleat ever so slightly and helps fill the gap so that there is no space for your for to roll.  As a result, your knee travels in an up and down plane.  This leads to less knee pain and more efficiency in the pedal stroke.  More efficiency, means less wasted energy.  This, in turn, means more power to the pedals.

So, for a quick $24.99 you can help increase power, increase efficiency and decrease knee pain.  Each packet contains 8 wedges, so depending on how many wedges you require (most require only 1), you could get 4-6 years of use out of each pack!