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No difference.

The adjustment is firmness not height.

Now, you might expect firmness to impact height, but that is not really the case.

Firmness in this case is dampening rate. The softer the setting, the faster the shock will respond and the farther it will travel in response to a given impact event.

Under a static load, you are more on the spring and will end up at the same height.
 

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No difference.

The adjustment is firmness not height.

Now, you might expect firmness to impact height, but that is not really the case.

Firmness in this case is dampening rate. The softer the setting, the faster the shock will respond and the farther it will travel in response to a given impact event.

Under a static load, you are more on the spring and will end up at the same height.
The above is totally incorrect. Preload only adjusts the ride height. It is used to set static sag.The dampening rate is in the case of the M109 built into the shock which as you know is not adjustable externally. OK!
 

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The above is totally incorrect. Preload only adjusts the ride height. It is used to set static sag.The dampening rate is in the case of the M109 built into the shock which as you know is not adjustable externally. OK!
Completely disagree.

Go adjust your setting and let us know what it does to ride height.

I have measured and it does nothing.
 

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It occurred to me that I may be using some term-of-art incorrectly, so let me boil it down to my actual point without potentially misusing some pre-defined term;

Crank that collar all you like and measure your height and there will be no change.
 

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I've never measured, but before I gained some weight, when I rode solo I set it on #1. People would commonly ask me how far I lowered it. There is a noticeable height difference with the pre-load adjustments.
 

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It occurred to me that I may be using some term-of-art incorrectly, so let me boil it down to my actual point without potentially misusing some pre-defined term;

Crank that collar all you like and measure your height and there will be no change.
:agree:but when you put rider and passenger weight on the bike when set at 1 the bike does sit lower from less spring tension.
 

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The above is totally incorrect. Preload only adjusts the ride height. It is used to set static sag.The dampening rate is in the case of the M109 built into the shock which as you know is not adjustable externally. OK!
:agree: And sag must be measured with the riders weight on the suspension.
 

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:agree:but when you put rider and passenger weight on the bike when set at 1 the bike does sit lower from less spring tension.
Agreed. That is why we call it preload. You are adjusting where a given amount of weight will fall in the possible range of motion of the nitrogen filled portion of the shock.

:agree: And sag must be measured with the riders weight on the suspension.
While that may be why you want to take the measurement, the idea of preload would be to make the adjustment so that load changes end up at the same height and therefore at the same starting point in the range of motion and therefore in the same range of dampening rate.
 

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Completely disagree.

Go adjust your setting and let us know what it does to ride height.

I have measured and it does nothing.
Good on yer! maybe the laws of physics & mechanics are different over there?

Certainly wouldn't let you get too close to to any race bikes suspension front or rear. ;)
 

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Good on yer! maybe the laws of physics & mechanics are different over there?

Certainly wouldn't let you get too close to to any race bikes suspension front or rear. ;)
And you are an expert how? Because you changed out your shock and ride a trike?

It is simple physics and there should not be much room for disagreement. Maybe I am not being clear here as is rather easy to do in this type of discussion, so I will try to water it down for you.

The spring holds most of the weight and determines, in large part, height under a given load.

The nitrogen cylinder controls what I will call dampening rate (I may be using this term incorrectly, but it is the only thing I can come up with to describe it)

Now, you can not adjust the nitrogen cylinder directly, but by adjusting the preload, you can change where in the cylinder's range of motion you find yourself at a given load. Thus, you indirectly control effective dampening rate with spring adjustment by changing where a given load sits in the cylinder's range of motion.

Parked, with no load, any spring setting should have you at the same height as even the softest setting will have the cylinder fully extended, which is what sets the max height without changing the shock or other components.

Under a load, you can see ride height differences from setting to setting, but the idea is to adjust the setting so different loads fall into the same range of the cylinder, thus netting you the same ride height under the different loads and netting you similar ride characteristics with the different loads.

Fully answering the OP's question directly is impossible with the information he has provided. We would need more data than it would be reasonable for the OP to provide as he could more easily measure loaded height on each setting.

So, what exactly are you disagreeing on?
 

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to truly change the ride hight you would have to do it with bones or a longer or shorter shock. that spring just adjusts the tension not the hight, with less tension on the spring and u set on it it goes down farther because there is less tension on the spring. the length of the shock does not change, :bdh::bdh::bdh:
 

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Square rounder you don't have to explain to this barsim. I am sure he doesn't have a clue on how a simple shock like the one on the works. We all know your knowledge of the 9 and you are a great contribution to this forum.:bigthumbsup:
 

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Square rounder you don't have to explain to this barsim. I am sure he doesn't have a clue on how a simple shock like the one on the works. We all know your knowledge of the 9 and you are a great contribution to this forum.:bigthumbsup:
I have learned far more here than I have contributed.

For all I know he is an expert and I may be explaining it in a way that makes me sound like a fool.

Just because you understand something does not mean you can explain it well, and this may be one of those instances.

It would be nice that when you call someone out for not knowing, that you actually explain where your disagreement is.

That is my issue here. I am rather sure that I get it. I am not sure I am explaining it very well.

It could even be that I do not actually understand it. There have been plenty of things I thought I knew for years and then discovered I had it all wrong when a better explanation was provided.

The problem is just saying 'your wrong' does nothing to contribute to a better understanding for anyone.
 

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I've never measured, but before I gained some weight, when I rode solo I set it on #1. People would commonly ask me how far I lowered it. There is a noticeable height difference with the pre-load adjustments.
:agree: I keep mine at 1 and it does drop. People ask me also what bones i have in it. I set it up to 4 this weekend to ride some two up riding and it did seem to be sitting higher. .
 

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Per Wikipedia:

Pre-load adjustment

Motorcycle suspensions are designed so that the springs are always under compression, even when fully extended. Pre-load is used to adjust the initial position of the suspension with the weight of the motorcycle and rider acting on it. Both the front forks and the rear shock or shocks can be adjusted for pre-load on most modern motorcycles.
The difference between the fully extended length of the suspension and the length compressed by the weight of the motorcycle and rider is called "total sag". Total sag is set to optimize the initial position of the suspension to avoid "bottoming out" or "topping out" under normal riding conditions. "Bottoming out" occurs when the suspension is compressed to the point where it mechanically cannot compress any more. "Topping out" occurs when the suspension extends fully and cannot mechanically extend any more. Increasing pre-load increases the initial force on the spring thereby reducing total sag. Decreasing pre-load decreases the initial force in the spring thereby increasing total sag.
Since the weight of the motorcycle and rider are the only forces compressing the suspension from the fully extended position, preload doesn't change the forces on the springs under riding conditions. Changing the pre-load does not change the way the suspension reacts to bumps or dips in the road surface either. Two simple examples using the motorcycle's forks shows why:

  1. Suppose that the bike and rider put a total weight on the front suspension of 300 lb. Suppose the spring rate of each fork spring is 50 lb per inch. Installing a 1 inch long spacer in each fork leg gives a pre-load of 50 lb per spring, a total of 100 lb. When the weight of the rider and motorcycle are loaded onto the suspension it will compress 2 inch from full extension (2 inches total sag). Now the force exerted on (and by) each fork spring is 150 lb (1 inch pre-load + 2 inch total sag = 3 inch total spring compression) for a total of 300 lb, balancing the weight of the bike and rider.
  2. Suppose we now install a 2 inch long spacer in each fork leg. The pre-load is now 100 lb per spring, a total of 200 lb. The total sag will change since we still have the same 300 lb loading the forks. The total sag will now be 1 inch. The total force on each spring is the same as before, 150 lb on each fork spring for a total of 300 lb force. The front suspension's initial position is 1 inch longer than in the preceding example (1 inch less total sag).
Since the forces are the same in both examples the reaction of the suspension to bumps and dips in the road will be the same. The difference is that there is less chance of topping out in example 1, less chance of bottoming out in example 2. Motorcycle manufacturers generally provide optimal total sag settings.
This is also why too-soft springs cannot be "fixed" by adding pre-load, too-stiff springs cannot be "fixed" by reducing pre-load. Changing to springs of the correct spring constant for the total weight of the bike and rider is the only solution.
Some motorcycles have externally accessible pre-load adjustments. Typically, this is a screw-type adjustment that moves a backing plate inside the fork against the top of the fork spring. The farther down the adjuster is screwed, the higher the preload.
A few motorcycles allow adjustment of pre-load by changing the air pressure inside the forks. Valves at the top of the forks allow air to be added or released from the fork.[2] More air pressure gives more preload, and vice versa.
Pre-load on bikes without adjusters can be changed by disassembling the fork and changing the length of the spacer between the top of the fork spring and the fork cap. Spacers can be installed under the rear shock springs similarly. A longer spacer gives higher preload, and vice-versa.
The pre-load on both forks should always be the same. Dangerous handling behavior and possible mechanical damage can result otherwise.
 

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I set mine on #1 when I first bought the bike, the idea being to lower the rear end. My buddy Sam has his set on 4. When they are parked next to one another, you can see the difference, even with no rider on the bike. We both have E-3 250s out back, and mine sits noticably further into the fender than his does. My wife can sit on mine and get both feet on the ground, she cannot on Sam's bike. But to be fair I have also pulled the fork tubes up in the trees about 1/2 inch.

I know what the purpose of the pre-load setting is, and I am rather light at 160 pounds, and also never ride two-up since my wife rides a M50. But still, I have always used the pre-load as a method of lowering the rear of my bikes, nothing else.

Amd it has worked for that purpose just fine in the 34 years I've been riding.
 

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Setting the preload up or down will not make the dismounted bike sit significantly lower or higher.

However when you sit on it it will squash down more - or less - depending on the preload. No two ways about it. Thats the aim of setting sag.

More preload = less squashing down or a higher ride height under your weight.
Too much preload = danger of topping out on bumps
Less preload = more squashing down or lower ride height under your weight.
Too little preload = danger of bottoming out on bumps.
This is fact.

Whats uncertain is whether more or less preload actually affects suspension hardness ie more preload = hard bumpy ride or less preload = soft wallowy ride.
According to the masters it does not affect stiffness. Real life experience often reports otherwise.

Skin.
 

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Discussion Starter · #20 ·
I am running a 280/10" rim at stock shock setting (4). Bike height is stock with stock bones. Is there any risk of damaging tire or bottoming out if I put the shock setting on (1)? Thanks again for all the information.
 
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