How far can a motorcycle lean?

[davidboda46]

http://www.wired.com/2015/09/just-far-can-motorcycle-lean-turn/

For those who didn't suck at math like I did... unfortunately this is all a bit too hard for my brain

Cheers,

David "Gonzo" Boda #46

[Boerenlater]

very far

[HornetMaX]

From the article:

The usual model for the static friction force (for a non-sliding tire) says that this friction force is proportional to the normal force.

But as we said in another thread, tyres are actually sliding all the time (or almost, at least a bit), so ...

Also: the reasoning using the turn radius is a bit bogus. The turn is not constant radius and the trajectory the bike takes neither.

But the conclusion is right: motorcycle tires are just awesome.

@Boerenlater: yeah but in you pic there are at least 4 contact patches

MaX.

[davidboda46]

From the article:

The usual model for the static friction force (for a non-sliding tire) says that this friction force is proportional to the normal force.

But as we said in another thread, tyres are actually sliding all the time (or almost, at least a bit), so ...

Also: the reasoning using the turn radius is a bit bogus. The turn is not constant radius and the trajectory the bike takes neither.

But the conclusion is right: motorcycle tires are just awesome.

@Boerenlater: yeah but in you pic there are at least 4 contact patches

MaX.

Well, I'm glad you got something out of it Max! 

[HornetMaX]

Well, I'm glad you got something out of it Max! 

It's very basic stuff: anybody with a little willingness can get it. I mean, with simple words and a lot of drawings, even Jamoz could (Jamoz, I know you read us here).

I'm under the impression that the guy who wrote it was/is surprised by the mu coefficient being > 1. But that shouldn't be the case: from wikipedia's page (Friction) you can read:

The coefficient of friction depends on the materials used; for example, ice on steel has a low coefficient of friction, while rubber on pavement has a high coefficient of friction. Coefficients of friction range from near zero to greater than one.

While in most relevant applications µ < 1, a value above 1 merely implies that the force required to slide an object along the surface is greater than the normal force of the surface on the object. For example, silicone rubber or acrylic rubber-coated surfaces have a coefficient of friction that can be substantially larger than 1.

[note that I do dislike the two sentences above: saying something ranges "from zero to greater than one" is a bit silly (even if I understand the intended meaning), and on the second quote, the coefficient is a property of the two materials, not only one. But I know I'm picky.]

MaX.

[CapeDoctor]

it still blows my mind when you lean on a banked track like Daytona, you can actually lean the bike horizontally, lol  (possibly even below the horizontal, i'm not sure?)

[HornetMaX]

it still blows my mind when you lean on a banked track like Daytona, you can actually lean the bike horizontally, lol  (possibly even below the horizontal, i'm not sure?)

Can't find a video right now but you have many circus-style shows where the bikes run in a circular arena with vertical "track" (like running inside a tumbler glass).
What may be surprising is that in doing so, the bike is almost peprendiculae to the "track" (but practically parallel to the ground), so the tyres have absolutely no merit in that performance (no lean angle).

BTW I asked my knowledgeable friend about tyres and mu coefficients: he says that that is, indeirectly, thanks to electronics (I feel Hawk getting an allergic reaction right now).
The reasoning is that a Traction Control allows for less spinning, hence lower tyre temperatures, hence softer compounds, hence mu > 1.
He checked (in Misano ...) with a bridgestone guy who confirmed mu>1 (but declined to say by how much, of course).

MaX.

[Napalm Nick]

Ah yes the "Wall of Death"

https://www.youtube.com/v/9H4jUptw4Vk

Can only be done by ladies due their mu co-efficiency.

[tseklias]

Ladies... no offense but even when they race radio controlled vehicles i wear a helmet  . You'd never predict the unpredictable. I have a question though, crashing in this thing must be really painful or not? I'm thinking of the steep elevation and after you stop rolling the fall in the centre of the circle?!

[Hawk]

it still blows my mind when you lean on a banked track like Daytona, you can actually lean the bike horizontally, lol  (possibly even below the horizontal, i'm not sure?)

Can't find a video right now but you have many circus-style shows where the bikes run in a circular arena with vertical "track" (like running inside a tumbler glass).
What may be surprising is that in doing so, the bike is almost peprendiculae to the "track" (but practically parallel to the ground), so the tyres have absolutely no merit in that performance (no lean angle).

BTW I asked my knowledgeable friend about tyres and mu coefficients: he says that that is, indeirectly, thanks to electronics (I feel Hawk getting an allergic reaction right now).
The reasoning is that a Traction Control allows for less spinning, hence lower tyre temperatures, hence softer compounds, hence mu > 1.
He checked (in Misano ...) with a bridgestone guy who confirmed mu>1 (but declined to say by how much, of course).

MaX.

..... Max, I'm just itching to get on my soap-box. Hehe! 

Hawk.

[Napalm Nick]

I like the round-cage version I saw at the Birmingham NEC Bike Show.

If you fall off it don't hurt, you go round like water down a drain, getting gradually lower until you are at the bottom where you just stand up.

The HSE (Health and Safety Executive) was alarmed by the "Wall of Death" name until they told him it was really " The Wall of a small friction burn" but didn't sound scary enough. Hence he compromised and said ladies only could use it due to their natural Airbags and mu efficiency.

All this true history can be found in the online Wiki.

[matty0l215]

The HSE (Health and Safety Executive) was alarmed by the "Wall of Death" name until they told him it was really " The Wall of a small friction burn" but didn't sound scary enough

Ahh, the HSE. My favorite bunch of Hi-vis and hard hat wearing, clip-board tapping, "I know your job better than you do, because I passed a test that had something to do with nothing", Fun Haters 

"That sounds dangerous, better ban it"