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GP Bikes => Setups => Topic started by: Desteban on March 27, 2014, 04:26:58 PM

Title: Preload
Post by: Desteban on March 27, 2014, 04:26:58 PM
Hey I have been playing with suspension for a long time now and am still a little lost at this point:

If I increase preload does it lift my bike? If so then I would have less sag, right?
But I noticed a bit preload on the rear is more stable under braking, because it feels my rear won't come of the ground so fast.
Therefore I thought increasing the preload reduces the supension travel and gives more sag. But I read everywhere differently so I wanted to ask what the value does ingame.
Title: Re: Preload
Post by: BOBR6 84 on April 08, 2014, 11:05:21 PM
If you increase preload you will have less ''static'' sag!

Try working on the rebound and compression settings more!

I doubt its possible to work out the suspension setup in relation to how heavy the rider is..

That would be good to have custom riders with different hight, weight, and riding style!
Title: Re: Preload
Post by: BOBR6 84 on April 08, 2014, 11:57:49 PM
I have lots of ''front end'' trouble on gpbikes. Not so much with braking but with turning and holding a line! On some corners/tracks the bike is trying to turn but something is stopping it?

This happens alot on brands hatch! The front end doesnt track properly around corners..

Is this a setup issue? Or a general gpbikes issue on modded tracks etc?

Title: Re: Preload
Post by: C21 on April 09, 2014, 08:38:07 AM
In my opinion it´s caused by modded tracks.
If you don´t have troubles at Victoria....
Title: Re: Preload
Post by: HornetMaX on April 09, 2014, 09:26:42 AM
More preload means you'll need a greater force to obtain the same compression of the rear shock absorber.
This means that more preload = less static sag as said, but it has other implications too (e.g. less squat).
Also, more preload = less extension available to follow the road when passing over a hole.

@BOBR6 74: some custom tracks have irregularities that do not play well with GPB physics. As suggested by C21, try to see if you have the same issue on Victoria.

MaX.
Title: Re: Preload
Post by: Hawk on April 09, 2014, 09:33:31 AM
Quote from: C21 on April 09, 2014, 08:38:07 AM
In my opinion it´s caused by modded tracks.
If you don´t have troubles at Victoria....

I absolutely agree C21.

I've looked at several max files of modded tracks that have obviously been ripped, and the track surface topology is terrible, especially on tight hairpin bends.

Maybe Piboso can confirm this, but the collision model is calculated from the surfaces of the mesh(Usually is I beleive?)
Well, if this is so, then if the surface mesh topology is chaotic and a lot of surface edges are so close to each other on corners that you couldn't fit a piece of paper in the space between some edges then I think this is what causes these problems with the collision model?
Don't know if I'm exactly right, but I think I'm on the right track with why there are grip and weird handling problems on certain corners.

I've not had a chance to look at the Victoria model mesh, so I cannot really comment, but I have notice that the Victoria track is pretty reliable for bike handling and performance. though on occasions their does seem to be a small problem with weird things happening on the 3rd bend from the end of the lap(Not sure what the corner is called, but it's the sharp right hand turn at the bottom of the hill.) :)
Title: Re: Preload
Post by: C21 on April 09, 2014, 01:26:23 PM
[OT]
I ususally develop bike physics on Victoria and did that quite satisfying (imho  ;D ).
As i turned to test on other tracks i was very disappointed.
Weird things happened on Brno (before the GP resurfacing) and other tracks....(before resurfacing most of the modded tracks were a pain to drive on (only my personal view on this!))

I returned to Victoria and the bike handled as suggested, making fun to drive (e.g. SC59 , Moto3,..) and getting a "realistic" feedback.
Victoria still has the crash issue on corner 10 down Lucky Heights but that´s most an issue with the 125cc and smaller bikes.....in my opinion it´s also caused by a bad track model...in reality there are not much crashs on that particular corner.
Title: Re: Preload
Post by: C21 on April 09, 2014, 01:56:39 PM
QuoteIf I increase preload does it lift my bike? If so then I would have less sag, right?
Yes./ Yes.

QuoteTherefore I thought increasing the preload reduces the supension travel and gives more sag
No.
Increasing the preload did not reduce the travel. It has no effect on the travel in terms of maximum travel value. It changes the ratio of positiv to negativ suspension travel. Changing the preload changes the initial position of the suspension.
Increasing the preload results in:
- lift of front and/or rear (increase in ground clearance)
- less sag
- decrease of negativ suspension travel.
Title: Re: Preload
Post by: BOBR6 84 on April 09, 2014, 09:15:59 PM
Yes the circuits I have the least trouble with are victoria, brno gp, paul ricard.

They seem to be the most reliable for me.. Although sometimes I have trouble going over lukey hights on victoria circuit! (the hill)
Depending how I enter the corner sometimes the front end doesnt find the grip. Almost like its dragging itself back inline?

I had trouble with the sharp right hand turn at the bottom of lukey hights but more so on beta3!

Thats why I asked about adjustable steering dampers in a previous post because on some slow turns the handlebars shake alot and it usually drops the bike!

I dont know if that would make a difference or if it is just the track surface etc like u guys say?
Title: Re: Preload
Post by: Hawk on April 09, 2014, 09:27:22 PM
Quote from: BOBR6 84 on April 09, 2014, 09:15:59 PM
Yes the circuits I have the least trouble with are victoria, brno gp, paul ricard.

They seem to be the most reliable for me.. Although sometimes I have trouble going over lukey hights on victoria circuit! (the hill)
Depending how I enter the corner sometimes the front end doesnt find the grip. Almost like its dragging itself back inline?

I had trouble with the sharp right hand turn at the bottom of lukey hights but more so on beta3!

Thats why I asked about adjustable steering dampers in a previous post because on some slow turns the handlebars shake alot and it usually drops the bike!

I dont know if that would make a difference or if it is just the track surface etc like u guys say?

Yeah.... Since I started riding in cockpit view, I also noticed the rider shaking the handlebars a lot, even on the straights, but particularly in certain corners even though not traveling fast.
I can only presume it is to do with the reaction to collision detections that have been calculated from badly modelled track surfaces. I hope Piboso can comment on this as it would be interesting to find out if this can happen because of bad modelling topology on the track surface and resultant collision detections?
Title: Re: Preload
Post by: Klax75 on April 10, 2014, 03:39:58 AM
The shaking handles, for me, using full manual lean. If I put the ride behind the wind screen and not hanging off the bike it goes away. So I just have to reposition my rider then I can take the corner.
Title: Re: Preload
Post by: Desteban on April 10, 2014, 06:09:38 AM
The shaking handle bars often tell me there is a setup issue. Most of the time it is fixable when you play with the rebound on the fork.

Hey about the preload I think Maxhud can prove that preload reduces the ride height. Gonna upload some pics once I have Internet again.
Title: Re: Preload
Post by: C21 on April 10, 2014, 06:34:23 AM
QuoteThats why I asked about adjustable steering dampers in a previous post because on some slow turns the handlebars shake alot and it usually drops the bike!
That´s not a steering damper issue. It´s caused by bad modelled track surface.
I had this on another track (i can´t remember the name) when i was testing and got handle bar shaking and fork travelling in a weird manner on a slow corner. It was so terrible that i quit testing on that track. I had this issue on that one only....so i say: It´s the track, not the bike  ;)

QuoteI have trouble going over lukey hights on victoria circuit! (the hill)
Depending how I enter the corner sometimes the front end doesnt find the grip. Almost like its dragging itself back inline?
That´s a normal behavior on that track. You can easy loose the front closing throttle near the apex of that corner because you will "overload" the front with that action and the weight distribution from rear (under accleration) to front (close throttle). That´s close to real....

QuoteI had trouble with the sharp right hand turn at the bottom of lukey hights but more so on beta3!
That´s still an issue and it´s caused imho by an incorrect track model comparing real layout to ingame layout. Imho the corner falls to much into the right....

QuoteHey about the preload I think Maxhud can prove that preload reduces the ride height. Gonna upload some pics once I have Internet again.
If you decrease the preload it will decrease the ride height, increasing will increase the right hide.
Title: Re: Preload
Post by: Desteban on April 10, 2014, 04:50:07 PM
Quote from: C21 on April 10, 2014, 06:34:23 AM
QuoteHey about the preload I think Maxhud can prove that preload reduces the ride height. Gonna upload some pics once I have Internet again.
If you decrease the preload it will decrease the ride height, increasing will increase the right hide.

In real life that is, according to max hud and the feeling I get during a ride 0 Preload is the max height and the max value of preload is the lowest height. You can test it yourself though, take a bike max the preload value and drop the bike in the pits. Then you can see the difference.
Title: Re: Preload
Post by: HornetMaX on April 14, 2014, 03:01:59 PM
Quote from: Desteban on April 10, 2014, 04:50:07 PM
Quote from: C21 on April 10, 2014, 06:34:23 AM
QuoteHey about the preload I think Maxhud can prove that preload reduces the ride height. Gonna upload some pics once I have Internet again.
If you decrease the preload it will decrease the ride height, increasing will increase the right hide.

In real life that is, according to max hud and the feeling I get during a ride 0 Preload is the max height and the max value of preload is the lowest height. You can test it yourself though, take a bike max the preload value and drop the bike in the pits. Then you can see the difference.
Hmm, can you document this with a couple of screenshots ? It sounds strange to me.

On a side note, I've been thinking for a while to have some sort of indication of the "ride height", but I've concluded that this shouold be shown by Piboso in the garage, as this measure is only available in the pits in real life, with the bike standing still.


Concerning the "shaking handlebars": it's very very hard to explain where it comes from without knowing the GPB internals. It's not even sure (at least to me) if it's something that comes from the bike model or from the "virtual rider".

One thing I can say is this: the GPB "virtual rider" is essentially a dynamic controller that tries to "invert" the motorbike physics. "invert" means that the "virtual rider" computes the physics inputs (e.g. steering torque) to obtain a certain set of outputs (e.g. lean angle), while the bike model does the opposite, it computes the outputs from the inputs.

Dynamic controllers based on model inversion are often very sensible to differences between the assumed model (the one inverted) and the real model (the real one GPB uses). In presence of uncertainties, model errors or approximations, the controller may have some weird behavior and in some cases it can generate large oscillating inputs in order to stabilize the closed loop system.

As a simple example (simple here is really relative), a linear system with flexible parts typically has complex poles with low damping: a controller inverting this kind of model is extremely sensible to the poles frequency and a small error may lead to the observed behavior (stable, but with large oscillating inputs) or worse (straight instability). This is one of the issues you have when you want to point a satellite (with large flexible solar panels) in the right direction.

Don't know how much all this is relevant to what we see in GPB, but the very fast handlebar shaking we see looks very suspect to me too.

MaX.
Title: Re: Preload
Post by: Desteban on April 14, 2014, 05:02:16 PM
When the guy is on the bike no matter how much you change the Preload value the suspension on the MaxHud stays the same, I think it is a bug within the game.
But when you drop the bike you can suddenly see the difference on MaxHud.


Preload 0
(http://www7.pic-upload.de/14.04.14/pf91aceck.jpg) (http://www.pic-upload.de/view-22870908/core-2014-04-14-18-26-30-17.jpg.html)


Preload Front 16 and Rear 8
(http://www7.pic-upload.de/14.04.14/rmc69ek9iva8.jpg) (http://www.pic-upload.de/view-22870907/core-2014-04-14-18-26-57-00.jpg.html)
Title: Re: Preload
Post by: HornetMaX on April 14, 2014, 05:17:11 PM
Hmm I wouldn't trust that much the indication when the bike is "crashed".

MaX.
Title: Re: Preload
Post by: Desteban on April 14, 2014, 05:29:47 PM
I actually do pretty much since I tried different preload settings and the suspension height changed accordingly when the bike was flat out on the ground.
Tried to take a look in replays if there is a optical difference when the bike is standing but doesn't seem to be the case.

On the other hand that confirms the feeling I get when riding, that increasing the preload does decrease the ride height.
Title: Re: Preload
Post by: HornetMaX on April 14, 2014, 05:31:08 PM
Yeah but what you see does not make sense: more preload = suspension more compressed when the bike is down ?

MaX.
Title: Re: Preload
Post by: doubledragoncc on May 05, 2014, 02:55:45 PM
The more preload makes the suspension stiffer as it puts pressure on the spring, therefore making the bike sit higher not lower. Imagine preload like putting a spacer between the fork spring and fork cap, that is basically how it is, but most forks now have a forkcap that you can turn the knob to spin a spacer up or down to increase/decrease preload.
Title: Re: Preload
Post by: C21 on May 06, 2014, 06:59:13 AM
Thrust me. Desteban Knows exactly what Preload does on a Real Bike.
[OT on]
@Deste
How was the Race last Weekend? 1st of the Saison and Bad Weather on the practice days ? ;)
[OT off]

The Problem is:
It seems to be that the Preload INGAME does Not compare to the Common Preload Setting in Real Life.
That's what he is Talking about ;)
I'm Not sure if you read the whole topic.....

Title: Re: Preload
Post by: HornetMaX on May 06, 2014, 10:08:17 AM
Hmmm ... I still wouldn't look at what happens when the bike is crashed.
However it does look strange that we don't seem to see any effect on the suspension position (when the bike is at rest) when varying the preload from zero to its maximum.

I have on means to check this properly but it should be trivial for Piboso to check.

MaX.
Title: Re: Preload
Post by: Desteban on May 07, 2014, 03:35:27 PM
Yeah sad we can't check this properly.

@C21
Race was really hard, had a bad crash on tuesday and was too weak to ride the bike fast. But prior to that I was pretty much in the middle of the pack
so I am satisfied for now. Weather was good till thursday and started getting better Saturday, even had dry qualy and sunny race so not much room for complains here  ;D
Aiming for Points next race in Zolder  8)
Title: Re: Preload
Post by: Warlock on May 07, 2014, 08:32:03 PM
hope you are ok Desteban, and good luck for the next one m8.  ;)
Title: Re: Preload
Post by: BOBR6 84 on May 07, 2014, 10:02:13 PM
What do you race desteban?

I feel silly replying to your first post hahaha
Title: Re: Preload
Post by: Desteban on May 08, 2014, 10:22:50 AM
@Warlock
Yeah I think I'll be fine till next race in 3 weeks. Thx mate, I need any luck I can get. Those guys are serously fast  ;D

@BOBR6
I race with an R6, something like stock 600 in germany.
Don't feel silly, I am still having problems to express what I mean properly with all those technical terms as English isn't my native
language. So in that regard you did answere my question just fine ;)