Fork Springs

[MidLife]

The fact that there's more spring displacement in one case forces the air to occupy a longer distance inside the fork, which would be the same effect as if we reduced the diameter of the tube. This seems to be the part that you disagree with.

Difficult to disagree when I am not sure of the point you are trying to make?

Are you saying the physics is wrong and the fork will not stroke exactly the same distance regardless of spring orientation?

I think the spring can be ignored because its volume doesn't compress,

You can't ignore the spring, it takes away a constant volume in the shrinking air chamber as you compress the fork

It is the reason why if you have a 200 mm column of air above the oil, it will take less than 100 mm of stroke to reduce the volume of air in half.

If you want visualization, cut off this upper part of the spring and pour an equivalent volume of oil in the tube, this is exactly the same situation. But now you can visualize the shorter column of air and understand why it will take less than 100 mm to halve the volume of air.

 

[Larry Fine]

From a Progressive Suspension instruction:

Install your new fork springs into the forks. Mechanically, it makes no difference which way the springs are installed. Some manuals will state; install the spring with the close wound end towards the bottom. This is done because sometimes there will be less spring noise. The springs will perform exactly the same regardless of which direction they are placed.


A post says: Wirth, Ikon, Progressive, Hagon, Wilbers all say tight coils up


And what I believe is an opinion:

Progressively-wound or dual-rate springs give an approximation of rising rate in that the close-wound part is the softest spring and compresses easily on small deflections. However on larger deflections the close-wound part goes coil-bound and the stiffer, loose-wound part does the work. At that time the close-wound part is doing nothing other than acting like a bush or spacer, and is dead weight. You don't want the dead weight to be unsprung (ie the weight of everything between the active part of the spring and the ground) therefore you want it at the top of the spring.

 

[Igofar]

This thread is starting to read like a bad episode of Big Bang theory
I simply pointed out a misprint in the service manual, that was verified by mother Honda (not a parts guy at a dealership) and also pointed out that on the ST1300 model, the OEM springs can only be installed correctly when the smaller end sits on the cartridge correctly, again, as mother Honda pointed out.
Now it seems every keyboard conspiracy commando is attempting to impose their will on everyone.
I don’t matter!
Put the springs in correctly, put the Correct amount of oil in, and go ride.

 

[Larry Fine]

My own take is this:

I think we agree that we should look at it from the bike's perspective, i.e., that the wheel assemblies move around the stationary bike. Also, that a laden ST weighs around 1K lbs, and a wheel assembly (tire, wheel, bearings, axle, brake rotors, etc.) and the moving suspension parts (lower fork sliders, damper rod, brake calipers and brackets, fender, etc.) probably 1/10 of the bike.

Let's say the suspension is being compressed, and the tight coils are now touching. With the tight coils down, they contribute to the moving mass of the front end, while the rest of the spring moves less. With them up, they don't contribute to moving mass, but the entire spring has to move upwards to compress them. I can see the advantages and disadvantages of each orientation.

I think that, while the few pounds of steel may have very little effect on the relatively-stationary mass of a 1K-lb bike, they may contribute more, percentage-wise, to the relatively-moving mass of the front wheel and suspension assemblies. So, while the actual effect may be imperceptible, when both ends are the same diameter, we have to pick an orientation, based on something.

 

[Larry Fine]

This thread is starting to read like a bad episode of Big Bang theory

I take that as a compliment.

Now it seems every keyboard conspiracy commando is attempting to impose their will on everyone.
I don’t matter!

No imposition intended, and certainly you matter.

Put the springs in correctly, put the Correct amount of oil in, and go ride.

Absoloopy!

 

[dwalby]

If you want visualization, cut off this upper part of the spring and pour an equivalent volume of oil in the tube, this is exactly the same situation. But now you can visualize the shorter column of air and understand why it will take less than 100 mm to halve the volume of air.

yeah, I had drawn out something like this after I was almost done typing the last post. Instead of oil, I used a solid rod of the same displacement as the spring in each orientation. I ended up with the same result of air volume and distance in the top part of the fork in both cases. I had already typed out the last post and I wasn't 100% sure either way, so I figured I'd ask one more time.

I'm guilty of overthinking things, thanks for taking the time to sort it out for me.

 

[MidLife]

......I had drawn out something like this........ Instead of oil, I used a solid rod of the same displacement as the spring in each orientation.

That's a good way to model it. May even be easier on our @Igofar!

I'm guilty of overthinking things.....

You were after another sound reason for up or down! Somebody had to do it.

 

[FastST]

What if the spring is upside down and the oil is missing about an inch from the top, and the air is not all the way up, vs when it is the other way around?

 

[Andrew Shadow]

This thread is starting to read like a bad episode of Big Bang theory
I simply pointed out a misprint in the service manual, that was verified by mother Honda (not a parts guy at a dealership) and also pointed out that on the ST1300 model, the OEM springs can only be installed correctly when the smaller end sits on the cartridge correctly, again, as mother Honda pointed out.
Now it seems every keyboard conspiracy commando is attempting to impose their will on everyone.
I don’t matter!
Put the springs in correctly, put the Correct amount of oil in, and go ride.

I may be wrong, up to the OP to clarify. My understanding is that it was an intellectual exercise from the outset. The question was asked out of intellectual curiosity in an attempt to understand if there is any valid technical reason why one orientation is better or worse than the other if there is no physical requirement to install the spring in a particular way. It was not asked with regard to the ST1300 specifically as far as I saw, so its particular requirement for installing the spring a certain would not seem to be relative to that question.

 

[FastST]

Install them differently in both forks. Go riding.