There are a lot of claims for the 5100 shocks, and I would like to explain two (what I would call) misconceptions. If you see any mistakes or have any questions, please tell me.

1. Preload

People say when you increase the perch setting you are "preloading" the springs. I don't know if the term preload is just thrown around, but regardless it is the wrong term when it is usually used.

A spring is defined by Hooke’s Law:

F= -kx

This means that with a force (F) and constant spring rate (k) a spring will always compress the same amount (x). When you adjust the perch setting on the shock, you are not changing the spring rate or the total force applied, so the spring will always compress the same amount -- moving the perch only changes the position of the spring seat (making the truck taller or lower), not the "preload" on the spring.

2. Perch Harshness

People claim that at higher perch settings the ride is harsher. We've established that the spring rate doesn’t change as the perch setting moves.

The 5100 is a viscous damper meaning its damping is velocity dependent and not position dependent. In that regard, perch setting shouldn't modify the harshness because the velocity of the shock isn’t dependent on perch height.

My assumption of people saying they feel a harsher ride is a result of new shocks, springs, the truck sitting taller, sway bars effective stiffness, etc.