Suspension rabbit hole

andyb · Nov 15, 2023

Calderara di Reno said:
Here we go ....

Swing arm 605mm, Fork extended 755mm, Fork extended to top of headstock 720mm, shock extended 307mm, 28mm offset clamp. 10.5 springs front and shock.

Base 2018 V4, stock swingarm pivot.

Note that the front is sitting higher than stock by a fair bit to get trail before the 28mm offset, opted to keep the front height as when I lowered it , I felt my braking was compromised .

I must admit I look at those numbers and think that's really low at the back and high at the front....

is this all the info you need Bruce? would be great to make some comparisons..

SA length
Fork free length
Fork height
shock free length
offset
and springs?
maybe add in rear rocker/ride height

JohnSmith · Nov 15, 2023

Here is an example of the definitive parameters in MotoSpec, its important to see as people tend to call things out differently

71493721136__B8579FD8-208F-4B88-AD4C-5FA9E0E73562-preview.JPG

andyb · Nov 15, 2023

did or have you put your std 23R numbers in to there Karl?

JohnSmith · Nov 15, 2023

yes, MotoSpec provided the 19 R spec settings - then was updated as best possible to reflect the 23 R

andyb · Nov 15, 2023

KarlKani said:
yes, MotoSpec provided the 19 R spec settings - then was updated as best possible to reflect the 23 R

So are the numbers from a std 23 The datum or point of reference to work from?

JohnSmith · Nov 15, 2023

I don't understand what you mean.
The 19 V4R specs were edited to reflect the 23 V4R measurements - That was my starting point

Calderara di Reno · Nov 15, 2023

Just checked out the Motospec website. Gets complex ?

Calderara di Reno · Nov 15, 2023

andyb said:
I must admit I look at those numbers and think that's really low at the back and high at the front....

is this all the info you need Bruce? would be great to make some comparisons..

SA length
Fork free length
Fork height
shock free length
offset
and springs?
maybe add in rear rocker/ride height

That's what i'm thinking that its high in the front , the stock seat is still giving me 830mm height, that's just an indicative/comparative height for the rear. It seems to be working with this geometry. Running 200/60 and 120/70

andyb · Nov 15, 2023

KarlKani said:
I don't understand what you mean.
The 19 V4R specs were edited to reflect the 23 V4R measurements - That was my starting point

Sorry it all gets a bit confusing

Doesn’t motospec already know the 23r numbers ?

JohnSmith · Nov 15, 2023

No they don't have it in the database
Or when I was using it in august they did not. But here is what it looked like with 19 R spec updated to 23 R

andyb · Nov 15, 2023

Do you have a direct comparison of numbers 19 to 23?

andyb · Nov 15, 2023

And looking at your numbers you increased the front spring rate and it shows the force on the tyre increased
Increasing the front spring didn’t effect the trail or rake

JohnSmith · Nov 15, 2023

OEM is 10.0
so my friend that was helping me wit this entered 10.5 + 9.5 to see results
I ended the season with 9.25

the PL setting was the same for all 3 spring rates so this will not change trail for rake

andyb · Nov 15, 2023

I also see you put rear shock at 315 wasn’t std 316?
And tie rod lengths 140
are you still on the std rocker ?

Clever stuff though… be interesting to see and compare with the OP numbers results…

JohnSmith · Nov 15, 2023

I just pulled he 1st image my friend sent thru. I went back and forth to adjust via text, the fork position is off too

baggerman · Nov 15, 2023

Calderara di Reno said:
That's what i'm thinking that its high in the front , the stock seat is still giving me 830mm height, that's just an indicative/comparative height for the rear. It seems to be working with this geometry. Running 200/60 and 120/70

Drop the front and move the trail towards 105. Slight CG change. Weird I would think it would run wide on the drive. But if it has enough anti-squat does that stop that? What do I know looks like Bruce will sort it out. Nice program.

Calderara di Reno · Nov 15, 2023

baggerman said:
Drop the front and move the trail towards 105. Slight CG change. Weird I would think it would run wide on the drive. But if it has enough anti-squat does that stop that? What do I know looks like Bruce will sort it out. Nice program.

When I first assembled I set the front lower as you suggested and it was the first setting I changed and raised it again. Has someone got an extended fork length to the top of the frame head stock as this is the only point that will be the same as my clamps are shaped differently to just say 3mm above

Calderara di Reno · Nov 15, 2023

Calderara di Reno said:
When I first assembled I set the front lower as you suggested and it was the first setting I changed and raised it again. Has someone got an extended fork length to the top of the frame head stock as this is the only point that will be the same as my clamps are shaped differently to just say 3mm above

Bruce Wayne · Nov 15, 2023

This is a basic look based on what data you gave me, your numbers are on the left non highlight. I put fork height as flush because this is an unknown ATM will upload a comparison next of STD offset vs your new offset.

Bruce Wayne · Nov 15, 2023

This one shows a comparison between the std offset and your 28mm this chart has basic sag calculated, left column is 28mm middle is 30mm and right column is calculated mid corner with 30mm offset. If you are able to give me an accurate fork position we can refine your geometry better. This is with the older Pirelli tyres not the newer profile. 120/70 and 200/60

Suspension rabbit hole

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