(WIP)Test - Tyre Grip Tuning for the 500cc Varase....

[Hawk]

Update: Saturday 14th June 2014 @ 00:36 hrs

Hi Guys.

There has been a discussion on the forum recently about the tyre/track grip characteristics, particularly for the 500cc GP 2 stroke bikes; that the 500cc GP 2 stroke bikes should be able to rear wheel power steer around the corners using the power of the engine through good throttle control. I have to say that I totally agree with this issue. I say this because surely if your cornering at max lean and fully open the throttle on one of these 2 stroke beasts the back end should easily spin around on you? At this moment and stage of GP Bike development this does not happen - Maybe someone with some real 500cc 2 stroke race bike experience can actually fill us in with the reality of this subject, but having seen and heard riders talk about it, my personal conclusion is that you have to have good throttle control and feed the throttle through the corner until you get a balance between spinning out and driving that rear wheel around the corners. This is just my reasoning and deduction from what I've heard riders talk about this subject.

Anyway... You guys know I like to test and experiment with GP Bikes, so yes, you guessed it, I have been experimenting with tuning the grip of the Varase 500cc GP 2 stroke bikes tyres to just see if we can get some semblance of being able to control the rear wheel spin while cornering just with throttle control only.
It has been very difficult to get a setting on the tyre grip that is kind of getting there, but I finally think we have a setting that isn't perfect, but is starting to show signs of those grip characteristics people have been discussing here on the forum.


Installation advice/notes: Please make sure you make a backup copy of the default Varase 500 bike your currently using and put it on your desktop or in another folder somewhere safe so that when you have finished with this test and want to go back to the original bike it is then easily copied back into the bikes folder of GP Bikes.

Tyre Grip Characteristics Altered : I've only altered the soft tyre grip characteristics, so make sure your on the soft tyres.

My test conditions: I've only tested it on the "Mallory Park 1978" track so I really don't know if the performance will be greatly different on other circuits. You can download the current(WIP) Pre Release version of the  "Mallory Park 1978" Circuit here: http://forum.piboso.com/index.php?topic=958.0

Online use: You cannot use this bike online as this files tyre physics have been altered and you would just get a "Data Mismatch" Error when trying to connect, so this test is a purely offline test.



Here is the download link for the Varase 500cc GP bike with the altered tyre grip characteristics: https://mega.co.nz/#!yIUhXKJY!UL_n9tZxoX11ni15Tq0DG6gTAB_KOgJj8Y5L9Io2Ijk
Give it a try and let me have your feedback here, good or bad, I don't care as all feedback is useful. 
All I ask is that you try and stick to the subject and not be biased by modern MotoGP bike performance as this is strictly a test to just try and get some performance characteristics of the old classic 500cc GP bikes, in particular,  from the 1970'/80's so please don't judge this on what you feel modern MotoGP bikes are like. 


Have fun!

Hawk.

[C21]

The only thing you did was to reduce asphalt 1 dry grip from 0,98 to 0,9595.....
All other values stay the same.
You will have more grip on asphalt 2 than on asphalt 1......don´t think that will be the correct way.
in my understanding the grade of the asphalt is in numerical order 1-3 ("best-good-worse"). So it has to be in a line from high to low value....
if you decrease the asphalt1 value you have to decrease or stay at the asphalt 1 value for 2 and 3 accordingly. (That´s how i do tyres ;-))

asphalt -> ASPH (Use this for main track surface) asphalt 2 -> BASPH (Same as ASPH, but slightly less grip) asphalt 3 -> CASPH (Slightly less grip than BASPH)

maybe it´s better this way:
asphalt1 -> dry grip = 0,9595
asphalt2 -> dry grip = 0,9495
asphalt3 -> dry grip = 0,9395
concrete -> dry grip = 0,9695 or 0,9595 (concrete should not be lower than AS1!)
(to stay at the reduction value you used for AS1).

-> only looked at the file, not driven yet, not @home 

it will be easier to upload/Download the tyre file only...size of 3kb than the whole bike...size of 24,4 MB!
or to say: open the specific tyre file and change value to: xxx 

[Klax75]

Just tried it out, renamed it varese_v594_tire, and in the varese_v594_tire.cfg and varese_v594_tire.ini, so it would show as a new bike.

With DST, it didn't feel any different then the normal Varese, with soft tires. Tires handled the same for me.

I tried Malloy '78, and NC_Mugello.

[Hawk]

@C21: Yes I understand what your saying, but this is just a quick test and I did state that I have only altered the soft tyre grip and to only use the soft tyres for this test. If this test and any subsequent tests turn out to be successful then that is the time to make sure that all tyre compounds are adjusted accordingly; most tracks as far as I am aware are using TRKASPH(highest grip) for the circuit track surfaces.

Thanks for you detailed feedback C21... Appreciated.


@Klax: Good idea for showing as a new bike, Max told me to do the same thing, but I thought for this initial quick test I would just post the default file format. But yeah... This is something I will do for sure if this takes off for the classic bike race category. 
I wondered about riding this with DST in helmet view because it's hard enough as it is to find any feedback as to what the bike is doing underneath you in helmet view, and I thought how the hell are you going to be able to really control a rear wheel power slide if you cannot see, or more importantly(in helmet view) feel anything? Must be extremely difficult to ride like you do and learn ways to get that feedback for what the bike is doing.

In Mallory Park, have you tried entering the 1st corner in 3rd gear, wait till your front end starts to turn well in and then open the throttle? Your rear wheel should start to slide round on you, then it's just a case of throttle control to keep it going without allowing the rear wheel to spin out on you.
You can do the same when you enter and exit the ESSES and coming out of Devils Elbow too... Oh and then the exit of the hairpin can be a little tricky also if your too hand-fisted with the throttle. LOL. 

Thanks for the feedback Klax.... Appreciated mate. 

[Hawk]

it will be easier to upload/Download the tyre file only...size of 3kb than the whole bike...size of 24,4 MB!
or to say: open the specific tyre file and change value to: xxx 

Thought about that too, but I think a lot of people don't like messing about with file internals. They feel a lot safer if they can just replace a folder for another one and then replace that folder back again to put things back to normal. 

Hawk.

[Vini]

Hmm, I don't see a lot of improvement.


In my opinion, we simply need more lean angle (or less weight, either way: more corner speed) and the bike would be perfect.


Powerslides like in MotoGP out of every corner will never be possible.
Even in reality, they were only able to do that a few times when they got lucky, but then again, I already have a some replays doing the same thing in GP Bikes with the 500.

[Klax75]

@C21: Yes I understand what your saying, but this is just a quick test and I did state that I have only altered the soft tyre grip and to only use the soft tyres for this test. If this test and any subsequent tests turn out to be successful then that is the time to make sure that all tyre compounds are adjusted accordingly; most tracks as far as I am aware are using TRKASPH(highest grip) for the circuit track surfaces.

Thanks for you detailed feedback C21... Appreciated.


@Klax: Good idea for showing as a new bike, Max told me to do the same thing, but I thought for this initial quick test I would just post the default file format. But yeah... This is something I will do for sure if this takes off for the classic bike race category. 
I wondered about riding this with DST in helmet view because it's hard enough as it is to find any feedback as to what the bike is doing underneath you in helmet view, and I thought how the hell are you going to be able to really control a rear wheel power slide if you cannot see, or more importantly(in helmet view) feel anything? Must be extremely difficult to ride like you do and learn ways to get that feedback for what the bike is doing.

In Mallory Park, have you tried entering the 1st corner in 3rd gear, wait till your front end starts to turn well in and then open the throttle? Your rear wheel should start to slide round on you, then it's just a case of throttle control to keep it going without allowing the rear wheel to spin out on you.
You can do the same when you enter and exit the ESSES and coming out of Devils Elbow too... Oh and then the exit of the hairpin can be a little tricky also if your too hand-fisted with the throttle. LOL. 

Thanks for the feedback Klax.... Appreciated mate. 

In helmet view you can tell if the back slips. Since your rider doesn't move his head left or right, and you get a left or right movement that is different from your turning angle, the back is slipping. You visually see it. I've had the back end come out on me a lot when using DST. When I am throttle out of a corning to help pick up the bike.

Just the new tires you made wasn't really much different then normal.

I'll give it some more laps.

[Hawk]

Just the new tires you made wasn't really much different then normal.

I'll give it some more laps.

Hi Klax.

The aim isn't to make a big noticeable difference, that would cause the grip of the rear tyre to be lost far too easily and uncontrollably when riders open the throttle while cornering. It does take a bit of practice to really appreciate the difference, but the difference is there I can assure you. 

However, this is just a first stage test. I can and will adjust things a little more but there is such a fine line between being able to control the slide and the rear tyre just breaking away uncontrollably.

My advice? Ride the bike as a 2 stroke and not as the devils own 4 stroke machines. I just love those 4 stroke bikes. Hehe 

Hawk.

[C21]

@hawk
I was Talking about the soft Tyre only
In my opinion the noticable difference should be a decreased lean angle. There is a direct Connection between dry grip factor and lean angle....there Are other values involved too.
Could be veryfied with MaxTM
That's only a theoretical opinion, i can't Ride it practically yet.
But the Feedback of the testers is Proving my Suggestion.
I think you have to change more thAn only the dry grip to get controlable slides. Normally tyres began also sliding When they are worn, don't know if GPB has fully implemented that yet.
You should Feel the Tyre wear After 50-75% Race Distance and at that Point slides should be taken more easily. Don't Rode more than 6-8 consustend laps so i don't know what Happens later

[Hawk]

@hawk
I was Talking about the soft Tyre only
In my opinion the noticable difference should be a decreased lean angle. There is a direct Connection between dry grip factor and lean angle....there Are other values involved too.
Could be veryfied with MaxTM
That's only a theoretical opinion, i can't Ride it practically yet.
But the Feedback of the testers is Proving my Suggestion.
I think you have to change more thAn only the dry grip to get controlable slides. Normally tyres began also sliding When they are worn, don't know if GPB has fully implemented that yet.
You should Feel the Tyre wear After 50-75% Race Distance and at that Point slides should be taken more easily. Don't Rode more than 6-8 consustend laps so i don't know what Happens later

Hi C

Do you know what needs to be changed and where I change it(a config file?) to achieve these proper changes to get the results we want for the classic bikes? If someone in the know could point my in the right direction then it would be good to test this alternative solution. 

Thanks C 

Hawk.

[HornetMaX]

For the wear I don't know as Piboso hasn't explained yet how wear is calculated nor the impact the wear has on the tire model.

I'm working on something to visualize the tire properties (curves for lat force vs slip angle, long force vs slikp etc) from the .tire files: not sure when I'll have something usable, but it should help understanding what we can change.

But once again, I'm not sure we will be able to provide a more controllable slide feeling just modifying the tires.

MaX.

[girlracerTracey]

Well I have to say I think this is a worthwhile and an interesting experiment.

I tried out an earlier version that Hawk sent to me last night and I liked it because the rear end of the bike was noticeably more reactive to the throttle. The back end moved around quite nicely when applying a surge of throttle slightly leant over on say the approach to a bend. Also a bit more movement on the exit to bends. For me it did feel more realistic. The throttle felt more connected to the rear wheel. I think it was a step in the right direction.

I tried the latest version Hawk released today and to be honest I didn't feel as much of a difference from the standard physics. Although I only had time to do a few laps.

Speaking as a gpbikes "novice" the problem as I still perceive it is that once you initiate a rear wheel slide the transition into that slide is far too abrupt and sudden. Also the tendency is that it doesn't slide in a gradual and "linear" manner (if linear is the right word  - sorry Max!) the bike just spins straight out from under you. In a bit of a mad spinning frenzy.. I can understand that effect exiting low speed bends but I cannot understand this effect to the extent that it is there exiting higher speed bends i.e. medium to high speed bends.

In real life, whilst a rear wheel slide was a challenging thing to control on a 500, I honestly think it would have been more controllable than it is in gpbikes. Which I guess is why there is some interest amongst you guys in looking at this. I think some of you feel the same way. On a careful throttle and on approaching the edge of adhesion (if that's the right word) even on a 500 I think it would begin to slide more gradually. Just a tad mind you. But the transition would be more gradual I think. Although challenging to control.

Also in gpbikes on the 500s I'm not really sure if its properly controllable once it is sliding..the technique was to maintain a controlled slide and not come off the throttle too quickly. Otherwise the rear tyre would grip again too quickly and you ran a real risk of a high-side. I have been watching my father's old videos of the classic 500cc grand prix from the 1980's and 1990's and you do see this effect quite a lot. Even on short powerslides exiting bends..if the rider got it slightly wrong. It would pitch you out of the saddle. Anyway, my problem is that I'm not reliably even getting to that point. Very rarely anyway if I am honest. The tendency for me is that the rear end just spins out from under me..that's the problem facing me. But granted I am very new to the "game".

Just my honest thoughts and I am sorry if I am repeating things I have already said before. On the other thread.

Having said all that I do think that Hawk's experiment represents a step in the right direction.

That's all I can say really. I think the opinion of you much faster guys on gpbikes is worth more than mine because I think you are way, way ahead of me in being able to initiate and hold rear wheel slides in gpbikes generally. Not just on the 500s.

I asked this before but can anyone here point me in the direction of a video where someone is rear wheel steering a 500cc bike round a bend in gpbikes? If people are able to do this, on the power rather than as a combination of power and track surface/track camber etc., I would really like to see it. Out of genuine curiousity. I would love to see how the experts and fast guys do it. Because try as I might I just can't..

grT 

[HornetMaX]

Speaking as a gpbikes "novice" the problem as I still perceive it is that once you initiate a rear wheel slide the transition into that slide is far too abrupt and sudden. Also the tendency is that it doesn't slide in a gradual and "linear" manner (if linear is the right word  - sorry Max!)

I'd prefer "progressive", but it's nitpicking.

In real life, whilst a rear wheel slide was a challenging thing to control on a 500, I honestly think it would have been more controllable than it is in gpbikes.

I guess this is the point where some of us disagree.

But that argument aside, it's funny how at the same time we have some players experimenting with less grip (to get more slide) and some others asking for more lean angle (which is possible essentially with more grip) or less weight, to have more speed in turns.

Also (I think I've already said but I'm not sure I was clear), I don't think that lowering the grip is the way to go (in order to get more controllable slide).
Some more complex change in the tire parameters are likely to be a better chance.

MaX.

[Desteban]

Just asking, but do you guys powerslide with an unloaded rear or an overloaded one? Because when I push hard with the 500cc on a fully loaded rear I tend to have some very nice slides.
If I accelerate with an unloaded rear too hard I am immeditely down, so I actually think the standard physics are pretty decent from what I have seen and heard of the 500cc.

[BOBR6 84]

I dont think the corner speed is fast enough in gpbikes with the 500cc.. Iv had some slides on the 500 at silverstone but mainly on woodcote corner after hitting a bump in the track.. Slid out nicely but was pure fluke that I stayed upright!

Maybe if corner speed was faster it would give more momentum for a slide to be progressive.. Then again that isnt rear wheel steering.. I think the bikes do already rear wheel steer (evident at victoria last corner) but not to the extent that you can control the spinning.. On the 500.

Its a worthy test but I cant see at the moment with throttle response, engine character, different track surfaces etc how your gonna find a ''sweetspot'' !?

I think the answer would be more grip from the tyre and the ability to go softer with fully working rebound dampening !

I dont think the rear loads up enough for rear wheel steering thats why it just kicks out.. Just a thought!