Effects of External Shock Adjustments
I am making this page for everyone to be able to see what is actually taking place when they make external adjustments on there shocks. And for those that want to make a spring change, they will now be able to see what is actually happening and exactly where in the travel there changes are taking place. Also for those that want to change crossover heights you can see what is going on here too!
First of all I need to define some terms. There are up to 4 springs that are available on a shock. (See fig. 1) I will refer to the main bottom spring as K1, the next tender spring up is the K2, the top spring on a triple rate shock is the K3 and on the Elka Long Travels they have a K4 Spring. Under the each spring other than the K1 spring there is a Crossover (see fig. 1). There are many different crossover heights available and these tell each tender spring when to crossover to the next stiffer spring. So the crossover behind the K2 spring I will refer to K2 Crossover.
Preload effects on Suspension
This is by far the most asked question that I get when someone is trying to set up there shocks. "I increased the preload and it helped from bottoming out as bad, but know it is riding rough in the initial part of the travel, what is wrong? Increasing the preload effects the entire spring rate range from beginning to end, but not a drastic difference. As you can see in the graph below it has about a 50 lb. gain everywhere with a 1/4" change in the preload on the springs. This is the reason that it helped with bottoming some, but now you have a harsher initial ride.
Changing the K1 Spring Rate
Some customers want to change there primary K1 Spring. As you can see below the 25 lb. change in the K1 spring increased the bottoming resistance of that shock by 100 lbs. And it was a gradual incline throughout the suspension curve. As that shock moves through the travel it gets stiffer than before. All of the dots on each line represents where the crossovers bottomed and as you can see by changing the spring rate it did NOT effect the position where these crossovers bottomed out.
Changing the K2 Spring Rate
As you can see below, changing the K2 spring rate is rarely done and now you can see why! The only reason that it would be changed is if there was a tremendous change in rider weight and a different A-arm setup that would most likely be so far off that a new set of shocks would be much cheaper to purchase. You can also see that this had no effect on the K3 crossovers, but with the different K2 spring rate it did change where the K2 crossovers bottomed out.
Changing the K3 Spring Rate
Here I have increased and decreased the K3 spring rate by 50 lbs. each way. As you can see, it has only affected the beginning of the travel. The only reason I would change this is if you have your preload set way down and the bikes ride height is too low.
Changing the K2 Crossover Height
Now I will show the changes of increasing or decreasing the height of the crossovers. As I've always said before, this is the most drastic EXTERNAL change you can do to a suspension. And now you will see why. First I will start by increasing and decreasing the K2 Crossover heights by 1/4". As you can see this changed not only where in the travel the crossover switched off from the K2 to the K1 spring, but it also changed the overall bottom out poundage by 50 lbs.
Changing the K3 Crossover Height
Changing the K3 Crossover height is going to change the spring rate curve earlier in the travel than if you changed the K2 crossover height. Although, it will also changed the overall poundage required to compresses the springs by 50 lbs. also.
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