A question about the AP Link

[scratchpad]

bare with me as im trying to learn this. 12.28 oem oal @blackout and 12.5 oal @mossrider seems short to me. @blackout is saying suspension could be adjusted to help but best suited through geometry. So how about longer shock length to get this 11 to 12.5 degrees?

Or, is this link the magic button everyone is missing out on? If so i want one.

 

 

[blackout]

2 hours ago, scratchpad said:

bare with me as im trying to learn this. 12.28 oem oal @blackout and 12.5 oal @mossrider seems short to me. @blackout is saying suspension could be adjusted to help but best suited through geometry. So how about longer shock length to get this 11 to 12.5 degrees?

Or, is this link the magic button everyone is missing out on? If so i want one.

 

 

The shorter link was one of Andy's first mods.  Most have it I thought.

 

If the shock is too long the shock clevis will start binding against the L-link at full extension.

[twf]

2 hours ago, scratchpad said:

bare with me as im trying to learn this. 12.28 oem oal @blackout and 12.5 oal @mossrider seems short to me. @blackout is saying suspension could be adjusted to help but best suited through geometry. So how about longer shock length to get this 11 to 12.5 degrees?

Or, is this link the magic button everyone is missing out on? If so i want one.

 

 

You already have swingarm angle set, without additional parts. 

[elmo]

Interesting topic, and would like to verify my swing arm angle.

How and where on the swing arm is this measured?

With wheel up, tried placing a smart level on the sprocket side of swing arm and was 18-degrees.

I do have the forks elevated 6mm above triple clamp, and 6mm extension on penske shock.

Thanks

 

 

[Mad]

In my opinion , and it is just my opinion  and so correct me if I'm wrong

 

We should consider a lot of things 

How can we affect the anti squat ?

The shock is made to work in a linear way , are the links making the motion progressive or regressive ? 

Is it possible to improve the overall geometry  ?

 

Now .. anti squat it's a complex effect , sprocket size , swingarm angle and length and sprocket position in relation to the swingarm pivot are some of the factors to consider and I'm not able to calculate a good set up 

 

I belive that the ap link will solve the problems related with linearity of the shock's motion , and doing so it will , as a consequence,  rise the height of the back and rising the back will modify the geometry but wheel's diameter and front fork position are a factor too 

But as we are talking about geometry we should think about the track ! Very twisty and slow ? Short and agile bikes do better , and we should consider a flatter swingarm angle and lowering the front can be beneficial. 

Fast and not really twisty ? A longer bike will give more stability and a bigger swingarm angle will provide meccanical grip .

We can raise the front to stabilize the bike during a very hard brake , maybe for a track with a slow turn after a long

Straight .

 

In conclusion I belive that the ap link is made to create a linear motion for the shock and rise the tail just enough to help turning , the new  swing arm angle may improve the meccanical grip and maybe just a little help with hard accelleration due to antisquat just as an added bonus but the negative may be instability on hard braking  

Edited September 22, 2018 by Mad

[twf]

Stock link is linear. 

[blackout]

3 minutes ago, elmo said:

Interesting topic, and would like to verify my swing arm angle.

How and where on the swing arm is this measured?

With wheel up, tried placing a smart level on the sprocket side of swing arm and was 18-degrees.

I do have the forks elevated 6mm above triple clamp, and 6mm extension on penske shock.

Thanks

 

 

This is how I did it.  Put bike on flat surface and close to level, side to side, with some blocks under the kickstand.  Insert rods in the hollow axle and frame pivot.  Take measurement from ground to center of rods.  Measure length of swingarm.  And you have enough numbers to compute the angle using some highschool math.  Sin is opposite over hypotenuse....  

 

Do this at full extension as that is what Dave Moss's numbers are at, 11 to 12.5 degrees.

[Mad]

16 minutes ago, twf said:

Stock link is linear. 

This is interesting, I assumed it was slightly progressive to give a little bit of comfort for street riding , would be interesting to properly measure the bike  

[blackout]

7 hours ago, Mad said:

In my opinion , and it is just my opinion  and so correct me if I'm wrong

 

We should consider a lot of things 

How can we affect the anti squat ?

The shock is made to work in a linear way , are the links making the motion progressive or regressive ? 

Is it possible to improve the overall geometry  ?

 

Now .. anti squat it's a complex effect , sprocket size , swingarm angle and length and sprocket position in relation to the swingarm pivot are some of the factors to consider and I'm not able to calculate a good set up 

 

I belive that the ap link will solve the problems related with linearity of the shock's motion , and doing so it will , as a consequence,  rise the height of the back and rising the back will modify the geometry but wheel's diameter and front fork position are a factor too 

But as we are talking about geometry we should think about the track ! Very twisty and slow ? Short and agile bikes do better , and we should consider a flatter swingarm angle and lowering the front can be beneficial. 

Fast and not really twisty ? A longer bike will give more stability and a bigger swingarm angle will provide meccanical grip .

We can raise the front to stabilize the bike during a very hard brake , maybe for a track with a slow turn after a long

Straight .

 

In conclusion I belive that the ap link is made to create a linear motion for the shock and rise the tail just enough to help turning , the new  swing arm angle may improve the meccanical grip and maybe just a little help with hard accelleration due to antisquat just as an added bonus but the negative may be instability on hard braking  

Yes, sprocket size and placement.  Not a concern for me now as that is not something I'm going to change.  But you are correct.

 

Swingarm angle, if you trust Dave Moss, set it to 11 to 12.5 degrees at full extension and start testing.

 

A modern Kawasaki ZX-6R has 120% anti-squat at ride height.  I doubt Kawasaki would design too much, so I don't think you will see any negatives until you go beyond that.

 

My goal for my bike next spring will be zero squat under acceleration out of corner 5,6 at NYST.  I hope to measure this with a Solo 2 DL and a potentiometer attached to the rear shock.  Keep in mind, over 100% anti-squat, the bike's rear will actually rise under acceleration.  If this happens according to the data logger, it might make sense to reduce swingarm angle and see how it feels.

[scratchpad]

3 hours ago, twf said:

You already have swingarm angle set, without additional parts. 

Im over here trying to figure out why my bike turns in and exits a corner so good without this link. 

 

I see what @mad is saying. With the oem dog bones and link it APPEARS to have a very slight curve in movement, w/o the shock attached, while in motion. With the shorter dog bones it would APPEAR to bring the rear shock mount on the link to a position that would make it more linear. Laymans perspective.

[elmo]

This just went from interesting to odd.

Made some adjustments added 3/4" ply at front to level out the axles, String line the centers of swing arm and angle went to 20 degrees.

However there is about 3/4" difference with tire profiles. with wheel contact  level, went  back to 18 degrees.

Last month at Sonoma raceway I was discussing my tire ware with Dave Moss, great source of information.

While I mostly ride C- track days, no plan to making any changes as I like the way its handling.

I also subscribe to Daves Tuning Total Access, and will probably see him next month at the Thunderhill raceway Keigwins event.

 

 

 

 

 

[blackout]

23 minutes ago, elmo said:

This just went from interesting to odd.

Made some adjustments added 3/4" ply at front to level out the axles, String line the centers of swing arm and angle went to 20 degrees.

However there is about 3/4" difference with tire profiles. with wheel contact  level, went  back to 18 degrees.

Last month at Sonoma raceway I was discussing my tire ware with Dave Moss, great source of information.

While I mostly ride C- track days, no plan to making any changes as I like the way its handling.

I also subscribe to Daves Tuning Total Access, and will probably see him next month at the Thunderhill raceway Keigwins event.

 

 

 

 

 

You don't want to level out the axles, but level out the bottom of both tires.  That's why I left the bike on my flat level floor.

[blackout]

The math I used.

[elmo]

blackout thank you for your time and replies, I apologize for my confusion.

My not so smart level I was in percent mode vs. degrees earlier. With level tires it appears I am in the sweet spot at 12 degrees .

Good lesson learned, thanks.

 

[enduro250]

yesterday evening, i have measured my swingarm geometry.

I leveled the bike and have taken all coordinates of all pivot points.

the wheels were completely relieved.

Under what conditions should the 11- 12.5 degrees be achieved
no load, weight of bike or weight of bike  + driver ?

with no load i have the following results between swingarm pivot and rearwheel axle
Heights difference  103 mm

length  difference (leveled) 502 mm

tan alpha = dH / dL

this result in a swingarm angel  = 11.6 degree
so please can anyone confirm my measurement
and please, what are the correct conditions to achieve 11 - 12.5 degrees

[blackout]

45 minutes ago, enduro250 said:

yesterday evening, i have measured my swingarm geometry.

I leveled the bike and have taken all coordinates of all pivot points.

the wheels were completely relieved.

Under what conditions should the 11- 12.5 degrees be achieved
no load, weight of bike or weight of bike  + driver ?

with no load i have the following results between swingarm pivot and rearwheel axle
Heights difference  103 mm

length  difference (leveled) 502 mm

tan alpha = dH / dL

this result in a swingarm angel  = 11.6 degree
so please can anyone confirm my measurement
and please, what are the correct conditions to achieve 11 - 12.5 degrees

Fully extended.  So that would be no rider or bike weight.  

[blackout]

Here you go, one of Dave's videos...

 

 

[enduro250]

please, can someone confirm my measurement and calculation, THX

[enduro250]

Unit of measurement in mm (sorry I'm in Europe)

[blackout]

1 hour ago, enduro250 said:

please, can someone confirm my measurement and calculation, THX

Calculations look good.

[enduro250]

but surprise:
why do I have a swingarm angel = 11.6 degree?
this is a standard set.

[blackout]

25 minutes ago, enduro250 said:

but surprise:
why do I have a swingarm angel = 11.6 degree?
this is a standard set.

I don't know.  My measurements could be off.  We really don't have an exact stock baseline yet.  The measurements are tricky taking with ordinary measuring tools.

[blackout]

1 hour ago, enduro250 said:

but surprise:
why do I have a swingarm angel = 11.6 degree?
this is a standard set.

Your swingarm length measured 512.5 mm doing the math.  I measured mine at 528.6 mm.  So that could be one reason why our numbers are different.  Swingarm length changes as chain wears and needs to be tightened.

[enduro250]

yes, I will remeasure this evening again!
but anyway, if I take your swingarm length, it results in 11.2 degree.
isn't the stock setup app. 9 degree ?
isn't that 9 degree angel the reason, why we should increase it to 11 - 12.5 ?

[blackout]

12 minutes ago, enduro250 said:

yes, I will remeasure this evening again!
but anyway, if I take your swingarm length, it results in 11.2 degree.
isn't the stock setup app. 9 degree ?
isn't that 9 degree angel the reason, why we should increase it to 11 - 12.5 ?

That's the numbers I got on my bike.  But again, just measuring with ordinary tools.  A small error can make a difference.  Maybe recheck with a angle finder and then take the average.  Either way, the AP link is a proven mod.