I can't get rid of this knee pop

Hi Jmartus, walk cycles are hard.  And dealing with knees is even harder.

To solve knee issues you need to figure out what the cause is (there can be many), but basically if the knee goes form straight to bent (or vice versa) too quickly, it will pop.

It could be that the head is too low, or you are raising the heel too much, or that the hip is too far away from the foot, or the foot is too far away from the hip.  Or a combination of them.

With your example, there's a few things going on, however, you can't fix it yet until you solve the bigger issues with the animation.

The 2 main issues are:

-The head up and and downs (not smooth enough).  It pauses at the top and then drops down.  The movement is too linear

-The feet are sliding.  

When the feet are on the ground they need to move at a constant rate.  I can see that the foot is being planted in front but it is staying in the same spot while it goes from the contact to the down position, while the back foot is still moving backwards.  This means that the front foot is actually sliding forward as he walking.

Try planting this foot further out in front, and then it should move backwards right from the first contact.

Hope that makes sense.

Anyway, once those this are solved, you will probably have new issues with the knees, but that is when it is time to solve it ;)