Changing preload on a linear rate spring does not make it stiffer.

[kml]

Changing preload has no effect upon spring stiffness . It only changes the ride height by changing where the shock rests in it's travel.

Cut and pasted from:

Teach Me Suspension (Part 3): Motorcycle Suspension Preload

Part 3 of our motorcycle suspension series takes a look at preload, what it does, and what happens to the bike when we make preload adjustments.

lifeatlean.com

The Springs Don’t Compress With Preload
Ok that’s not strictly true. An unladen, fully extended fork (or shock) spring WILL compress when preload is added.

However, under yours and the bike’s weight, when preload is added the spring in the forks and shock do not compress. The spring remains the same length, but the forks and shock themselves actually extend.

Sounds confusing I know, but let me explain.

Imagine someone holding onto the rear of your bike, letting it rest upright under its own weight.

At that point in time, the springs will be compressed by a given amount based on the rate of the spring and how heavy the bike is.

When you wind on preload, the adjuster starts to push down on the spring and it tries to compress it, but in doing so you are changing the amount of force that the spring pushes straight back up (remember our earlier examples).

That then means that the spring needs MORE weight to be applied to it in order to compress it, thereby cancelling out a portion of the bike’s weight that was originally causing it to compress.

The spring’s length under the bike’s load doesn’t change, but now the fork (or shock) has actually extended.

More information

Motorcycle Rear Shock Adjustment | Cogent Dynamics | Motorcycle Suspension

Cogent Dynamics rear shocks are custom built for each customer and are delivered with settings which are excellent for most circumstances yet are designed with flexible adjustability.

www.motocd.com

cheers
ken

 

[Kiwi Rider]

Changing preload has no effect upon spring stiffness . It only changes the ride height by changing where the shock rests in it's travel.

Cut and pasted from:

Teach Me Suspension (Part 3): Motorcycle Suspension Preload

Part 3 of our motorcycle suspension series takes a look at preload, what it does, and what happens to the bike when we make preload adjustments.

lifeatlean.com

The Springs Don’t Compress With Preload
Ok that’s not strictly true. An unladen, fully extended fork (or shock) spring WILL compress when preload is added.

However, under yours and the bike’s weight, when preload is added the spring in the forks and shock do not compress. The spring remains the same length, but the forks and shock themselves actually extend.

Sounds confusing I know, but let me explain.

Imagine someone holding onto the rear of your bike, letting it rest upright under its own weight.

At that point in time, the springs will be compressed by a given amount based on the rate of the spring and how heavy the bike is.

When you wind on preload, the adjuster starts to push down on the spring and it tries to compress it, but in doing so you are changing the amount of force that the spring pushes straight back up (remember our earlier examples).

That then means that the spring needs MORE weight to be applied to it in order to compress it, thereby cancelling out a portion of the bike’s weight that was originally causing it to compress.

The spring’s length under the bike’s load doesn’t change, but now the fork (or shock) has actually extended.

cheers
ken

Very well explained. Thanks Ken, it’s always good to clear up the misinformation and misconceptions around spring preload and it’s effect.

 

[c10]

What about progressive springs?

 

[kml]

What about progressive springs?

Progressive rate springs are another matter. On most street bikes the springs are linear.

 

[c10]

The reason I ask as my ZRX had Works performance piggy back pro racers with a Dual spiring set up , and one was a progressive while the other was a set spring . My wifes 600 bandit has a progressive front fork springs also .

 

[Cantab]

My wifes 600 bandit has a progressive front fork springs also .

As did my SV1000N, GSX1400 , Busa and BKing

 

[kml]

The reason I ask as my ZRX had Works performance piggy back pro racers with a Dual spiring set up , and one was a progressive while the other was a set spring . My wifes 600 bandit has a progressive front fork springs also .

I am not sure , but if you adjust the preload while the shock is on the bike and compressed from the load of the bike and you don't increase the weight that the shock is supporting and the shock is free to move in its travel that progressive springs would act the same as liner rate springs. In other words the shock would only move in its travel when the preload is changed.

if weight is added the first part of the softer travel would be used changing the spring rate. for example adding a passenger.

any links on the action of progressive springs and the effect of preload on them would be appreciated.

cheers
ken

 

[kml]

Interesting reading here.

Motorcycle Suspension - Springs Advanced

Motorcycle Suspension Springs - Spring force, Spring rate, Progressive, Digressive, Dual-rate, Top-out springs, Preload

www.promecha.com.au