How much lean angle have I got?

[Mental Trousers]

It's interesting that people think that doing low speed circles in a car park in more likely to result in a bin and therefore is scary. Carparks and similar areas (the odd disused runway, closed roads etc) are where the majority of rider training takes place. The object of doing circles is not to get your knee down etc. It's to get used to having a bike leaning over and knowing what it feels like. If you lean over far enough you'll find out what it's like to get near the limits of your tyres. Don't know how exploring the limits at 30kph is dangerous or scary.

[Ocean1]

However, it is not the size of the contact patch that determines what friction you have available! That depends only on the normal force and the coefficient of friction.

So you’d expect to see little or no difference in traction over a wide range of tyre pressures?

COF varies not only with the tyre compound characteristics but with the road surface, there’s a compromise between local compound deformation and contact area to be optimised, that’s why realfastdudes mess with the pressure depending on which surface they’re on. In fact the compromise is way more complicated than simple COF considerations, tyre deflection is much less controled than the suspension so it's likely that running higher pressures than those required for optimum static friction pays dividends.

I won't question that you can design a tyre that will have more grip at lean than in the upright position. However I would argue that it is a matter of variations in the coefficient of friction - not because the contact patch changes.

Wonder if there’s any benefit to be had by compartmentalising carcases to allow different pressures across the tyre width… Doubt it, progressive compounds probably already provide whatever advantages can be had there. Think there’s still way more to be had from compound development though, and real-time reactive suspension.

[Ocean1]

It's interesting that people think that doing low speed circles in a car park in more likely to result in a bin and therefore is scary. Carparks and similar areas (the odd disused runway, closed roads etc) are where the majority of rider training takes place. The object of doing circles is not to get your knee down etc. It's to get used to having a bike leaning over and knowing what it feels like. If you lean over far enough you'll find out what it's like to get near the limits of your tyres. Don't know how exploring the limits at 30kph is dangerous or scary.

But I don’t think that. And I agree that such practice, (with expert advice) is good for finding that “near the limit” point. I think such post-novice, non-racing focused training would be great, is it available?

[Mikkel]

So you’d expect to see little or no difference in traction over a wide range of tyre pressures?

COF varies not only with the tyre compound characteristics but with the road surface, there’s a compromise between local compound deformation and contact area to be optimised, that’s why realfastdudes(TM) mess with the pressure depending on which surface they’re on. In fact the compromise is way more complicated than simple COF considerations, tyre deflection is much less controled than the suspension so it's likely that running higher pressures than those required for optimum static friction pays dividends.

I never argued that the COF was a constant.
Indeed COFs are bloody complicated. It is however quite possible to establish a rough estimate if you know the surface materials and temperature of the two relevant surfaces. If you want detail you have to consider micrometer-scale geometry which for all intents and purposes are beyond the scope of any real considerations.

Again, if we include too many variables it quickly becomes extremely difficult to discuss even the most simple scenarios.

But yes, tyre pressure is very important too. Some people don't even think of tyres as being part of the suspension setup - although they play a crucial part.

[90s]

If you lean over far enough you'll find out what it's like to get near the limits of your tyres. Don't know how exploring the limits at 30kph is dangerous or scary.

Because the discussion has been to find the limit by going too far and crashing, which is often the only true way to establish where the real let-go point is. Which is dangerous and scary, even in controlled conditions. And I don't recall any posts mentioning that this should be at 30kph. When I leaned to bin it was at about 60kph that I found how far I could lean on a tight mini-roundabout before the bike went down.
And worse than dangerous and scary, exspensive. And pointless to, unless you are a funded track-racer to be honnest.

[Mental Trousers]

But I don’t think that. And I agree that such practice, (with expert advice) is good for finding that “near the limit” point. I think such post-novice, non-racing focused training would be great, is it available?

Most post-learners courses cover that sort of thing if people request it, with many others doing that or something similar as standard. Learning what the bike feels like near it's limits is very important for safe riding. The courses I've done in the past (both for riders and for instructors) have covered this sort of thing.

[Oldfulla]

Mental-Trousers,
what are the courses that you have done in the past that addresses what a bike feels like when it is pushed to its limits? I would be interested in something like this. Who runs them?

btw, this thread is getting to be a long read, but a good discusion. Interesting to see all the different and varying views out there, thanks to all who have contributed


Cheers

[onearmedbandit]

+1.

This thread is a good example of motorcycling discussion still very active on KB. Notice how those that say KB is only full of crap now are noticeable by their absence.

Back to your normal program.

[Brett]

AS already noted, how long is a piece of string? Too many variables to give a definitive answer.

[Mikkel]

AS already noted, how long is a piece of string? Too many variables to give a definitive answer.

Nah, there's a pretty big difference...

With the string question there is one unknown variable - which could easily be calculated if you knew e.g. the mass, the material and the thickness of said string.


However, with regards to the discussion in this thread there are too many, interconnected variables that will change dynamically as the bike moves.

And yes, this is irrelevant, you are right - I'm just being a contrary bastard

[onearmedbandit]

AS already noted, how long is a piece of string?

Nah, there's a pretty big difference...

With the string question there is one unknown variable - which could easily be calculated if you knew e.g. the mass, the material and the thickness of said string.

See, that's the thing with you engineer type guys, too complicated. That one unknown variable could easily be found with a ruler. Or tape measure.

[Ocean1]

See, that's the thing with you engineer type guys, too complicated. That one unknown variable could easily be found with a ruler. Or tape measure.

I is simple.

Besides, if at any stage questions are being asked about the length of a bit of string you don't need a tape, it's not long enough. Murphy's law y'know.

[CookMySock]

If you lean over far enough you'll find out what it's like to get near the limits of your tyres. Don't know how exploring the limits at 30kph is dangerous or scary.

Its just that everything happens much more quickly at low speed. At 100clicks in a sweeper, lines can be adjusted with a tiny bar push and they feel very controllable - and I guess they can be at 30clicks too, but the bars feel lighter it seems to be less stable.

That is all unfortunate, coz 100clicks in a sweeper is not exactly the place for a noob to have a brain fart. Though, the same brain fart at 30k will drop your bike - it just won't kill you as well.

DB

[Mikkel]

See, that's the thing with you engineer type guys, too complicated. That one unknown variable could easily be found with a ruler. Or tape measure.

Troll!

And of course Ocean1 is correct about Murphy's law - it's the 0th law of thermodynamics!

And I'll just keep quite about the fact that you just reapply the ruler/tape measure the necessary number of times to complete the measurement...

[90s]

I is simple.

Besides, if at any stage questions are being asked about the length of a bit of string you don't need a tape, it's not long enough. Murphy's law y'know.

Now Murphy knew all about testing the limits until meltdown. He was a rocket-sled tester. They were probably less safe than they sound.

Unless you are Murphy, play it safe.

But as I am on that tip, I have to post my favourite Murphy story. One of his teams tested 'plane cockpits for birdstrike. Thy developed a cannon that fired a chicken at the glass. They leant it to a well-known 'plane manufacturer who phoned up totally furious - "your damn cannon nearly killed someone - the chicken smashed through the cockpit, ripped through the lenght of the plane and lodged in the rear bulkhead".

"Well, next time defrost the chicken ..."