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Discussion Starter #1
This is a starting point for traction at different temperatures. As the saying goes "All models are wrong, some are useful." We know countless variables will invalidate the graph. With that said, what changes would be suggested? Basically it's a guide for riders who have no concept of temp and traction. @speedfinn Can you comment?
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This is a starting point for traction at different temperatures. As the saying goes "All models are wrong, some are useful." We know countless variables will invalidate the graph. With that said, what changes would be suggested? Basically it's a guide for riders who have no concept of temp and traction.
I dont agree with a chart that does not even address what brand of tire, what compound of tire, what ambient temperature was used for the chart foundation, and the list could go on.

I run Pirelli SC1 front and SC2 rear. I dont care if they last 500 to 800 miles as that number even is dependent on ambient temps. I can do 58 degree lean angles right off the trailer with no tire warmers if I want. I have rode Deals Gap Dragon many times straight into the hard riding making lean angles 58 degrees. Good riders can put the heat into a tire. Good setup can put the heat into the tires.
 
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I dont agree with a chart that does not even address what brand of tire, what compound of tire, what ambient temperature was used for the chart foundation, and the list could go on.

I run Pirelli SC1 front and SC2 rear. I dont care if they last 500 to 800 miles as that number even is dependent on ambient temps. I can do 58 degree lean angles right off the trailer with no tire warmers if I want. I have rode Deals Gap Dragon many times straight into the hard riding making lean angles 58 degrees. Good riders can put the heat into a tire. Good setup can put the heat into the tires.
Must have high ambient temps for that. Try that in Ireland on SC and youll be on your ass
 

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I dont agree with a chart that does not even address what brand of tire, what compound of tire, what ambient temperature was used for the chart foundation, and the list could go on.

I run Pirelli SC1 front and SC2 rear. I dont care if they last 500 to 800 miles as that number even is dependent on ambient temps. I can do 58 degree lean angles right off the trailer with no tire warmers if I want. I have rode Deals Gap Dragon many times straight into the hard riding making lean angles 58 degrees. Good riders can put the heat into a tire. Good setup can put the heat into the tires.
Thats really weird compound choice to be fair.

Normally people would run SC2/SC1 front and SC1 or SC0 rear.
 

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The graph means a tire needs to be at its ideal operating temperature to allow leaning more. Tire shoulders don't heat up as fast as the center especially if they are made of separate compounds.
There are 4 main variables with temps & traction:

Track pavement temp
Track pavement abrasion (smooth Vs harsh pavement)
Tire compound (hard, soft, etc...) & ideal operating temperature range
Tire pressure

We can only control the last two above.
 
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Discussion Starter #10
In this graph the tires can generate a theoretical max coefficient of friction of 1.0. That preculdes the need to name the tire or surface type.

If you have a new track rider and you say to them: "Look, your tires are cold, take it easy for the first few laps." That may mean very different things to different riders. We need some sort of general starting point. Basically we need to know, for an average tire and surface what the friction coefficient would be at different temps. I was supplied with coefficient/temp graph from a tire engineer which helped me make this first draft. Has anyone seen a graph like this anywhere else?
 

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Discussion Starter #11
I dont agree with a chart that does not even address what brand of tire, what compound of tire, what ambient temperature was used for the chart foundation, and the list could go on.
This would be with the assumption that both the tires and ambient are the same at the lower starting temps, e.g. 70F means tires and road are 70F.
 

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In this graph the tires can generate a theoretical max coefficient of friction of 1.0.
In that case max lean angle should be only 45 deg.

If we assume that rider does not move ass, and we measure chassis lean angle, then it can be over 45 deg.
But then we have to know CoG height and tire widths, and then it is not theoretical anymore.

Or we can just forget the coefficient of friction and make table for lean angles 0-55 deg with temp scale 32-210F?
 

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Then, second problem is tyre type vs temperature.

Street tyre @32F, you can drive with moderate lean angles.
Track tyre @32F, probably disintegrates.

Street tyre @210F, more like soap.
Track tyre @210F, max lean angle and go go go!

So you really can not use same theoretical table for street and track tyres.
 

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Discussion Starter #14
In that case max lean angle should be only 45 deg.

If we assume that rider does not move ass, and we measure chassis lean angle, then it can be over 45 deg.
But then we have to know CoG height and tire widths, and then it is not theoretical anymore.

Or we can just forget the coefficient of friction and make table for lean angles 0-55 deg with temp scale 32-210F?
Agreed, for the newer riders I'd show this to, most wont understand 45 degrees from center of contact patch to combined CofG, so I figured about 55 deg being around 1g on flat ground being typical. The assumption being a 190 or 200 rear tire.
 

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Discussion Starter #15
Then, second problem is tyre type vs temperature.

Street tyre @32F, you can drive with moderate lean angles.
Track tyre @32F, probably disintegrates.

Street tyre @210F, more like soap.
Track tyre @210F, max lean angle and go go go!

So you really can not use same theoretical table for street and track tyres.
For sure. I'm thinking something like a street-legal track tire.
 

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Discussion Starter #17
Soft/ medium/ hard compound street-legal track tire
or
Single or dual compound street-legal track tire?
I'm thinking of a Dunlop Q3+ (dual compound, at 30 degrees lean you're off the center band) or Pirelli Diablo Supercorsa (single compound, medium).
 

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As Dylan said, "all models are wrong; some models are useful". I spent 31 years a military analyst culminating as the Colonel directing the Defense Modeling and Simulation Office. A graph like this is based on one very specific set of assumptions; change one sensitive assumption and the whole thing changes. The better way to think about and use this type of chart is to change the x-axis from being quantitative to qualitative, i.e., instead of 0-60 degrees of lean, make it read "Little or No Lean" at one end and "Max Lean" at the other end. Doing this conveys the learning point while minimizing the battle of assumptions.
 

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Discussion Starter #19
As Dylan said, "all models are wrong; some models are useful". I spent 31 years a military analyst culminating as the Colonel directing the Defense Modeling and Simulation Office. A graph like this is based on one very specific set of assumptions; change one sensitive assumption and the whole thing changes. The better way to think about and use this type of chart is to change the x-axis from being quantitative to qualitative, i.e., instead of 0-60 degrees of lean, make it read "Little or No Lean" at one end and "Max Lean" at the other end. Doing this conveys the learning point while minimizing the battle of assumptions.
Thanks for that. Your job must have had you knee deep in complex calculations far more difficult than this.
 

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Discussion Starter #20
I guess my question to all would be this:

If you were taking a friend to a trackday for the first time and it was cold, with no warmers, would you show them the graph, or skip it?
 
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