I was doing some suspension research and came across this. Moss didn't bring up "top out springs" or how to correct for them in any of his videos, and I don't remember seeing them mentioned anywhere else either. This guy says the rear has them too. This makes things more complicated! (if he is correct)

Ask the Geek: Fork Top-Out Springs
Your abnormal guide to things abnormal
From the October, 2010 issue of Sport Rider
By Andrew Trevitt

I recently purchased a 2008 ZX-14. I had no problems getting the shock set up but when it came to adjusting the fork I was completely puzzled by the results I was getting. By running the adjusters through the extremes of adjustment my useable range of sag was between 42mm and 56mm. Typically, I set sag to 30mm front and rear. I have set sag on the numerous sportbikes I have owned over the past 26 years and have never encountered anything like this. I searched the Internet and the only real information I found was on Race Tech's site. The info leads me to believe I have encountered what's known as "top-out" springs. I have read the Race Tech tip "Sport Bike Relaxed Preload" but it is still unclear to me how I go about setting up fork sag properly on this bike. Race Tech says the bike has a long top-out spring and "this requires 20mm relaxed preload minimum". Does this mean I just deduct 20mm from my calculations to get the correct sag? I am not sure how to go about setting the fork sag on this particular bike, could you enlighten me?
Dan Forest
Goffstown, NH

Yes, the ZX-14 has long, soft top-out springs in the front fork, and that does make it difficult to set sag properly. Originally, top-out springs were intended to provide a soft buffer for the fork to fully extend against when - for example - the front wheel came off the ground. But over the last few years, other advantages have been found by using long, soft top-out springs in both the fork and shock. The chart shows how the overall spring rate in a fork is affected by the addition of a top-out spring. The rate near full extension changes as the top-out spring compresses, effectively working against the main spring's extension. The advantage can be seen here: with a conventional setup, it takes a significant amount of force (20kg in our example) to compress the fork at all. This means that as you accelerate out of a corner, if there is less than 40kg of weight on your front wheel (20kg on each fork tube) the suspension won't budge. This leads to the front end skipping over bumps and potentially causing headshake. A fork with long top-out springs will move with any force applied at all, making it much more compliant over small bumps accelerating out of corners.

Race Tech defines relaxed preload as how much the spring would be compressed when installed if the top-out spring were to remain fully extended. But the top-out spring compresses when the main spring is installed, meaning you would have to disassemble your fork to make these measurements and check. How the main spring and top-out spring interact depends on the rate of each, so there is no set rule to use when setting sag. You will certainly want more than 30mm to account for the top-out spring, but not necessarily 20mm more.

In these cases it's best to set sag based on how your bike handles. Put a zip tie on a fork tube to make sure the fork is not bottoming, and experiment with front preload settings to see how your bike reacts to the changes. Pay particular attention to its behavior exiting corners, as the other danger is that the fork will still top out under acceleration. Record your sag numbers as you go, so that if you start to make internal changes you'll have a baseline to work from. Note that your ZX-14 also has a top-out spring in the shock; the same concept applies to the rear shock under braking, when the rear wheel is skimming over the pavement. You may want to experiment with your rear sag setting as well.

BS! Look, sag is weight on the spring. If static weight has been established, then the springs are going to sag under that pre-spring tension in the fork. Why would this guy take apart the fork to find a fully extended spring? Is not sag the compression of the spring and now set the sag to your sagging the bike down? Now, tighten/loosen set sags?

I set sag front and rear as soon as I had all the crap off the bike. I don't use clothes because they can hardly push the spring down you bag your clothes and set it on the back seat. Say a 60lbs dog might move some spring, but not 6-8 pounds of jeans and shoes.

All that bounce Moss does, you rather pull the frame up and let it drop. That pushing up and down is one way, but a simple drop will set the weight down and of you are consistent with the same procedure and the same person calling the numbers off the tape measure, you static drop the frame and what is that number? Sit on the bike. What is that number? You're still bouncing the bike and for what?

There are your two numbers and now find center. Set sag in the middle. From there you go tight/loose; for your other sets are for speed returns up and plunges on the speeds down. If you want a stiffer ride, go half turns or full turns and test. I set mine to the softer settings. If I ran hard, I'd run stiffer numbers. But @ 65 mph speeds or less? I like it soft for the sad ass infrastructure around here.

Don't ask me if that front end leaves the hands because of the spring tension as he states. It is more a flick of the hing no matter how stiff of soft you deflected the front end. The bike rolls over bumps pretty plushly. The same hole I hit using the same line and forgetting about that spot in the canyon I sink myself into; I always look around at the front end to see if I bent that front rim? The rear going over is seems less harsh.

Do I hear the front bottom or top out? Nada! I hear a good initial noise of all that was a good smack to the front end. But to hear that traditional top/bottom tap-out?

I don't think I have had to worry about bottoming out either, but sometimes I notice that smack on the front end when hitting the most humble of driveway approaches. Before painting my front fender I also had a spot on the top where it was brushing against the fairing under the light assembly. Sport/touring bikes have always been made soft from the factory. I never felt sag was that complicated to finger out though.

I dialed in more preload and such when I retuned my suspension after getting all the GIVI luggage etc.

I'm heavy, my gear is heavy, and she doesn't wallow or bottom out on me when I travel. She is a little squirrely in real twisty stuff with all the kit on, but once you figure her out she goes through just fine.

All forks and shocks have "sag" in them if they have springs, thats just the nature of springs. But a) the engineers understand that and design accordingly, and b) it isn't enough to merit discussion.

But we will anyway. :)

I'm not sure why this got my brain spinning. Progressive springs have been around a long time. Just needed a slap or 2 to snap me out of it. Thanks guys!

Hub; "I don't use clothes because they can hardly push the spring down you bag your clothes and set it on the back seat."
So you set your sag naked? Way too much info!