1st Shock on left is just sitting there, no weight on it. The preload is just enough to hold the shock in the center of travel.
2nd shock has a weight is placed on it. It compresses the spring and drops the shock and weight down. In this drawing it's bottomed out. Rough ride.
3rd shock has that weight, but the preload adjuster is screwed upwards, lifting the load and centering the shock travel. The spring compression is exactly the same as shock #2.
4th shock is has the preload adjusted just like the 3rd shock. But this one has a much smaller weight, like a smaller rider. Now the shock is topped out and the spring is less compressed. This is what happens to many little riders on a stock Harley shock btw.
5th shock has had the preload way over adjusted, raising the shock to the very top even with the heavy load on it. In fact, it's compressed the spring even more. The shock is topped out and rather unwilling to move because of the excessive preload.
It will not compress down to 4 inches if there is an inch (100lbs) of pre-load applied. If you apply 200lbs, 100 will be required to overcome the preload and the other 100 will compress the spring 1 inch.
YES! THAT'S IT! YOU GOT IT! YOU AGREE WITH ME! You just didnt' do the simple math to realize you agree with me.
The spring is 5 inches after there is one inch of preload. The first 100 pounds just overcomes the preload. Then the 2nd 100 pounds only compresses the spring one inch. How big is that? How much is one inch less than 5 inches? Say it! Say it!
Last edited by Durango Dave; 02-24-2016 at 10:40 AM.
So I guess you're saying the motorcycle suspension will feel exactly the same to the solo rider when it has been sag adjusted for 2 up as it did when adjusted for solo. It's just higher. That's not my experience.
Your experience is correct, it will NOT feel the same in the initial travel where we spend most of our time; larger hits however will be the same. I found a good explanation below.
Spring Pre-load and spring rate - CHANGING PRE-LOAD DOES NOT CHANGE SPRING RATE. You don’t get a stiffer spring by adding pre-load. Rather you change the weight point at which the spring starts to move. Once the spring starts to compress it will move at its spring rating. Example: Using a 100 pound linear-rate spring, preloaded one-quarter inch, would take twenty-five pounds of force before it would further compress. In effect the spring will not compress until 26 pounds of force were applied. The spring rate however has not changed, even though it initially takes 50 pounds of force to move the initial one-quarter inch, it would continue compressing one-quarter inch for every additional 25 pounds of force applied throughout the active length of the linear-rate spring, until the coils touch each other (bind).
Dave , you are not correct but I'm tired of trying to explain it to you so you win by default because I'm not posting after this , you keep trying to explain to me what I already know and admit , the spring rate never changes , it can't that is consistent, yes weight is what compresses it when standing still , I never said it didn't , that's how you set the sag , however once the bike is in motion going down the road hitting bumps and holes the shock moves up and down because of terrain differences , not weight , this is the job of the shock , adding preload will cause the shock to give more resistance which will make it ride stiffer , technically the spring IS NOT stiffer , it can't be , reality because you've add preload it will ride stiffer , trust me I should run my shock with about 1" of sag , I run it with 3/4" of sag , not only does the bike sit higher , it rides much more firm or stiff what ever you want to call it , if you add preload and say your bike doesn't ride firmer or stiffer you are lieing
YES! THAT'S IT! YOU GOT IT! YOU AGREE WITH ME! You just didnt' do the simple math to realize you agree with me.
The spring is 5 inches after there is one inch of preload. The first 100 pounds just overcomes the preload. Then the 2nd 100 pounds only compresses the spring one inch. How big is that? How much is one inch less than 5 inches? Say it! Say it!
Say what exactly? That un-preloaded the system will deflect 2 inches compared to 1 inch for the pre-loaded system when 200 lbs of force is applied. You are aware that if you've consumed some spring deflection with pre-load that it isn't then available for suspension travel, right??
Seeing your fondness for internet wisdom, take a look at their example of why it takes 50# to deflect a 100# spring by a quarter inch after pre-loading.
Your experience is correct, it will NOT feel the same in the initial travel where we spend most of our time; larger hits however will be the same. I found a good explanation below.
Spring Pre-load and spring rate - CHANGING PRE-LOAD DOES NOT CHANGE SPRING RATE. You don’t get a stiffer spring by adding pre-load. Rather you change the weight point at which the spring starts to move. Once the spring starts to compress it will move at its spring rating. Example: Using a 100 pound linear-rate spring, preloaded one-quarter inch, would take twenty-five pounds of force before it would further compress. In effect the spring will not compress until 26 pounds of force were applied. The spring rate however has not changed, even though it initially takes 50 pounds of force to move the initial one-quarter inch, it would continue compressing one-quarter inch for every additional 25 pounds of force applied throughout the active length of the linear-rate spring, until the coils touch each other (bind).
Looking at the above picture you adjust the preload when the cycle is unloaded. For that reason the shock is extended as far as it can go (it is topped out). If it has a preload of 100 pounds then that needs to be overcome before the suspension moves at all. If you put a small child on your cycle the shock will still be topped out. If an adult sits on the cycle it will compress the suspension. Once the suspension starts to move it will move at its spring rating. In other words the preload affects when the suspension will top out (and bottom out). The spring rate will apply all the time your are riding. As the link above states after the preload is overcome the spring will compress one-quarter inch for every additional 25 pounds of force applied (that's the spring rate of 100 pounds per inch) So if a very light person were to ride your cycle or if the preload was misadjusted then the suspension would be topped out and feel very firm. and your cycle would be high. So yes the preload can make your ride hard but only if it is missadjusted too far one way or the other. Your weight must overcome the preload or you need to readjust your preload. They say your suspension should be compressed only 25% to 30% when sitting still. That gives only about 25% decrease before you top out and 75% increase before you bottom out. Keeping the preload set like this makes sure that your suspension is riding at your spring rate.
On the other hand progressively wound springs (also called progressive spring rate) do have one one spring rate until the suspension is about to bottom out then the spring rate increases for that last bit of travel. Preload does not do anything of the sort. http://sonicsprings.com/catalog/prel...ch_article.php
All suspension springs have preload. When they build a shock at the factory the spring must be preloaded to install it on the shock. What if we had zero preload? They could build a shock so long that the spring would fit on it without compressing it at all. This shock could be installed on a motorcycle. When you ride this cycle it would ride exactly like the ones that have preload except it would never top out. The only difference is when you go to work on the cycle, you would jack it up and up and up before the back tire would come off the ground.
So you can see a shock without any preload rides like one with preload. Once the preload is overcome the spring rate is what determines the suspension.
But now what if you were to load down this motorcycle that has special shocks and a passenger were to get on. It would bottom out. Now what if you were to add preload? As the experts say you would "change your ride height and your sag". The bike would ride higher and prevent bottoming out. But I don't want to do that. Adding preload might add that magical spring stiffening force above and beyond the spring rate the tj316 keeps talking about. Without adding any preload we could just increase the travel before the cycle were to bottom out. With that much travel the cycle would sit high like a dirt bike when unloaded.
It is very important to realize if you increase the preload without loading more onto your cycle the spring will not be more compressed as you ride. At the risk of sounding like a broken record the experts say you would only "change your ride height and your sag". Since you have overcome your preload the amount the spring will be compressed depends entirely on the spring rate and the weight on the cycle. Look at the above picture and think about that statement. When you move that preload ring up or down the all the weight is still on the springs (unless you are topped out or bottomed out).
Good discussion. Foxtrapper has helped with his posts and drawings. As all the experts say "Preload is the most misunderstood facet of suspension tuning." It is not intuitive. "All it does is change your ride height and your sag."
Since this is not the way you would intuitively think preload would work I don't mind questions from anyone other than tj316 and Bmusg. I'm getting tired of those two saying things like "the spring wouldn't compress down to 4 inches. It would only compress one inch less than 5 inches"
Do you want to learn? When your understanding is so different than the experts than someone must be wrong and I don't think it's the experts.
Last edited by Durango Dave; 02-27-2016 at 11:05 AM.
If you want to learn call a shock expert and talk to them , Durango Dave is an idiot and totally doesn't understand a single thing he is reading or posting. Better yet you don't even need shocks , you can replace them with two steel rods bolted on the side of your bike , because according to Dave NOTHING will compress a shock other than weight , therefore once your preload is set and you sit on your bike you can ride up and down the road and the shock will not move because no weight has been added , oh and so you don't think I'm name calling Dave I've shown your ramblings to a few shock experts and they said this guy is an idiot and doesn't unstand anything he's read and posted , so carry on I'm done with you , when a person is determined like you to be right they will never accept the truth.
Looking at the above picture you adjust the preload when the cycle is unloaded. For that reason the shock is extended as far as it can go (it is topped out). If it has a preload of 100 pounds then that needs to be overcome before the suspension moves at all. If you put a small child on your cycle the shock will still be topped out. If an adult sits on the cycle it will compress the suspension. Once the suspension starts to move it will move at its spring rating. In other words the preload affects when the suspension will top out (and bottom out). The spring rate will apply all the time your are riding. As the link above states after the preload is overcome the spring will compress one-quarter inch for every additional 25 pounds of force applied (that's the spring rate of 100 pounds per inch) So if a very light person were to ride your cycle or if the preload was misadjusted then the suspension would be topped out and feel very firm. and your cycle would be high. So yes the preload can make your ride hard but only if it is missadjusted too far one way or the other. Your weight must overcome the preload or you need to readjust your preload. They say your suspension should be compressed only 25% to 30% when sitting still. That gives only about 25% decrease before you top out and 75% increase before you bottom out. Keeping the preload set like this makes sure that your suspension is riding at your spring rate.
On the other hand progressively wound springs (also called progressive spring rate) do have one one spring rate until the suspension is about to bottom out then the spring rate increases for that last bit of travel. Preload does not do anything of the sort. http://sonicsprings.com/catalog/prel...ch_article.php
All suspension springs have preload. When they build a shock at the factory the spring must be preloaded to install it on the shock. What if we had zero preload? They could build a shock so long that the spring would fit on it without compressing it at all. This shock could be installed on a motorcycle. When you ride this cycle it would ride exactly like the ones that have preload except it would never top out. The only difference is when you go to work on the cycle, you would jack it up and up and up before the back tire would come off the ground.
So you can see a shock without any preload rides like one with preload. Once the preload is overcome the spring rate is what determines the suspension.
But now what if you were to load down this motorcycle that has special shocks and a passenger were to get on. It would bottom out. Now what if you were to add preload? As the experts say you would "change your ride height and your sag". The bike would ride higher and prevent bottoming out. But I don't want to do that. Adding preload might add that magical spring stiffening force above and beyond the spring rate the tj316 keeps talking about. Without adding any preload we could just increase the travel before the cycle were to bottom out. With that much travel the cycle would sit high like a dirt bike when unloaded.
It is very important to realize if you increase the preload without loading more onto your cycle the spring will not be more compressed as you ride. At the risk of sounding like a broken record the experts say you would only "change your ride height and your sag". Since you have overcome your preload the amount the spring will be compressed depends entirely on the spring rate and the weight on the cycle. Look at the above picture and think about that statement. When you move that preload ring up or down the all the weight is still on the springs (unless you are topped out or bottomed out).
Good discussion. Foxtrapper has helped with his posts and drawings. As all the experts say "Preload is the most misunderstood facet of suspension tuning." It is not intuitive. "All it does is change your ride height and your sag."
Since this is not the way you would intuitively think preload would work I don't mind questions from anyone other than tj316 and Bmusg. I'm getting tired of those two saying things like "the spring wouldn't compress down to 4 inches. It would only compress one inch less than 5 inches"
Do you want to learn? When your understanding is so different than the experts than someone must be wrong and I don't think it's the experts.
Foxtrappers pics are good but they don't represent your shocks. Going from 2-3 he's showing the top and bottom spring keepers to be changing positions, this doesn't happen. Your bottom mount is fixed. As you add pre-load the spring compresses and the top of the shock extends. You not only don't understand what pre-load is but it's clear you don't understand what sag is either. Sag is spring deflection. If you have less sag, its because the spring is deflecting less under the same load. How is this? Because part of the weight is now supported by pre-load. You now have an increased starting load to overcome before your spring deflects freely. That increased starting load never goes away. Read the works performance links again. Better yet, go adjust half the sag out of your shocks and take the bike for a ride.
Bsmug , you are correct , anyone with a coil over shock go ride your bike and hit a bump , then add preload and hit the bump again , next put less preload than you originally started with and hit the bump again . You will instantly fill your suspension stiffened and softened from your original settings , don't take anyone's word test yourself and you will know.
according to Dave NOTHING will compress a shock other than weight
Is inertia the word you are looking for? Newton was amazed that inertial mass had the extreme coincidence to have the exact same value of gravitational mass. Heavy objects fall at the same rate and light objects. Research why Einstein said this was no coincidence at all.
Oh and a word of advice: don't doubt what Einstein said until you understand the topic.
Originally Posted by tj316
oh and so you don't think I'm name calling Dave I've shown your ramblings to a few shock experts and they said this guy is an idiot and doesn't unstand anything he's read and posted , so carry on I'm done with you , when a person is determined like you to be right they will never accept the truth.
yea yea you've talked to "experts" that aren't on the internet. And all the experts on the internet say something different so you can't provide any links to prove your point. http://lmgtfy.com/?q=what+does+suspension+preload+do
Last edited by Durango Dave; 02-27-2016 at 12:10 PM.
02-24-2016 | 10:12 AM
